Issues with ON CONFLICT UPDATE and REINDEX CONCURRENTLY

Subject: [PATCH] error report in case of invalid index used as arbiter
test for issue with upsert fail
---
Index: src/test/modules/test_misc/t/006_concurrently_unique_fail.pl
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/test_misc/t/006_concurrently_unique_fail.pl b/src/test/modules/test_misc/t/006_concurrently_unique_fail.pl
new file mode 100644
--- /dev/null	(revision 9446f944b415306d9e5d5ab98f69938d8f5ee87f)
+++ b/src/test/modules/test_misc/t/006_concurrently_unique_fail.pl	(revision 9446f944b415306d9e5d5ab98f69938d8f5ee87f)
@@ -0,0 +1,158 @@
+
+# Copyright (c) 2024, PostgreSQL Global Development Group
+
+# Test REINDEX CONCURRENTLY with concurrent modifications and HOT updates
+use strict;
+use warnings;
+
+use Config;
+use Errno;
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Time::HiRes qw(usleep);
+use IPC::SysV;
+use threads;
+use Time::HiRes qw( time );
+use Test::More;
+use Test::Builder;
+
+if ($@ || $windows_os)
+{
+	plan skip_all => 'Fork and shared memory are not supported by this platform';
+}
+
+my ($pid, $shmem_id, $shmem_key,  $shmem_size);
+eval 'sub IPC_CREAT {0001000}' unless defined &IPC_CREAT;
+$shmem_size = 4;
+$shmem_key = rand(1000000);
+$shmem_id = shmget($shmem_key, $shmem_size, &IPC_CREAT | 0777) or die "Can't shmget: $!";
+shmwrite($shmem_id, "wait", 0, $shmem_size) or die "Can't shmwrite: $!";
+
+my $psql_timeout = IPC::Run::timer($PostgreSQL::Test::Utils::timeout_default);
+#
+# Test set-up
+#
+my ($node, $result);
+$node = PostgreSQL::Test::Cluster->new('RC_test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->append_conf('postgresql.conf', 'fsync = off');
+$node->append_conf('postgresql.conf', 'autovacuum = off');
+$node->start;
+$node->safe_psql('postgres', q(CREATE UNLOGGED TABLE tbl(i int primary key, updated_at timestamp)));
+
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+# IT IS NOT REQUIRED TO REPRODUCE THE ISSUE BUT MAKES IT TO HAPPEN FASTER
+$node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i, updated_at)));
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+my $builder = Test::More->builder;
+$builder->use_numbers(0);
+$builder->no_plan();
+
+my $child  = $builder->child("pg_bench");
+
+if(!defined($pid = fork())) {
+	# fork returned undef, so unsuccessful
+	die "Cannot fork a child: $!";
+} elsif ($pid == 0) {
+
+	$node->pgbench(
+		'--no-vacuum --client=20 -j 2 --transactions=100000',
+		0,
+		[qr{actually processed}],
+		[qr{^$}],
+		'concurrent INSERTs, UPDATES and RC',
+		{
+			# Ensure some HOT updates happen
+			'002_pgbench_concurrent_transaction_updates' => q(
+				BEGIN;
+				INSERT INTO tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+				COMMIT;
+			),
+			'003_pgbench_concurrent_transaction_updates' => q(
+				BEGIN;
+				INSERT INTO tbl VALUES(42,now()) on conflict(i) do update set updated_at = now();
+				COMMIT;
+			),
+			'004_pgbench_concurrent_transaction_updates' => q(
+				BEGIN;
+				INSERT INTO tbl VALUES(69,now()) on conflict(i) do update set updated_at = now();
+				COMMIT;
+			),
+		});
+
+	if ($child->is_passing()) {
+		shmwrite($shmem_id, "done", 0, $shmem_size) or die "Can't shmwrite: $!";
+	} else {
+		shmwrite($shmem_id, "fail", 0, $shmem_size) or die "Can't shmwrite: $!";
+	}
+
+	my $pg_bench_fork_flag;
+	while (1) {
+		shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+		sleep(0.1);
+		last if $pg_bench_fork_flag eq "stop";
+	}
+} else {
+	my $pg_bench_fork_flag;
+	shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+
+	subtest 'reindex run subtest' => sub {
+		is($pg_bench_fork_flag, "wait", "pg_bench_fork_flag is correct");
+
+		my %psql = (stdin => '', stdout => '', stderr => '');
+		$psql{run} = IPC::Run::start(
+			[ 'psql', '-XA', '-f', '-', '-d', $node->connstr('postgres') ],
+			'<',
+			\$psql{stdin},
+			'>',
+			\$psql{stdout},
+			'2>',
+			\$psql{stderr},
+			$psql_timeout);
+
+		my ($result, $stdout, $stderr, $n, $begin_time, $end_time);
+
+		# IT IS NOT REQUIRED, JUST FOR CONSISTENCY
+		($result, $stdout, $stderr) = $node->psql('postgres', q(ALTER TABLE tbl SET (parallel_workers=0);));
+		is($result, '0', 'ALTER TABLE is correct');
+
+		$begin_time = time();
+		while (1)
+		{
+			my $sql = q(REINDEX INDEX CONCURRENTLY tbl_pkey;);
+
+			($result, $stdout, $stderr) = $node->psql('postgres', $sql);
+			is($result, '0', 'REINDEX INDEX CONCURRENTLY is correct');
+
+			$end_time = time();
+			diag('waiting for an about 3000, now is ' . $n++ . ', seconds passed : ' . int($end_time - $begin_time));
+
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			last if $pg_bench_fork_flag ne "wait";
+		}
+
+		# explicitly shut down psql instances gracefully
+		$psql{stdin} .= "\\q\n";
+		$psql{run}->finish;
+
+		is($pg_bench_fork_flag, "done", "pg_bench_fork_flag is correct");
+	};
+
+	$child->finalize();
+	$child->summary();
+	$node->stop;
+	done_testing();
+
+	shmwrite($shmem_id, "stop", 0, $shmem_size) or die "Can't shmwrite: $!";
+}
Index: src/test/modules/test_misc/t/007_concurrently_unique_stuck.pl
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/test_misc/t/007_concurrently_unique_stuck.pl b/src/test/modules/test_misc/t/007_concurrently_unique_stuck.pl
new file mode 100644
--- /dev/null	(revision 9446f944b415306d9e5d5ab98f69938d8f5ee87f)
+++ b/src/test/modules/test_misc/t/007_concurrently_unique_stuck.pl	(revision 9446f944b415306d9e5d5ab98f69938d8f5ee87f)
@@ -0,0 +1,165 @@
+# Copyright (c) 2024, PostgreSQL Global Development Group
+
+# Test REINDEX CONCURRENTLY with concurrent modifications and HOT updates
+use strict;
+use warnings;
+
+use Config;
+use Errno;
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Time::HiRes qw(usleep);
+use IPC::SysV;
+use threads;
+use Time::HiRes qw( time );
+use Test::More;
+use Test::Builder;
+
+if ($@ || $windows_os)
+{
+	plan skip_all => 'Fork and shared memory are not supported by this platform';
+}
+
+my ($pid, $shmem_id, $shmem_key,  $shmem_size);
+eval 'sub IPC_CREAT {0001000}' unless defined &IPC_CREAT;
+$shmem_size = 4;
+$shmem_key = rand(1000000);
+$shmem_id = shmget($shmem_key, $shmem_size, &IPC_CREAT | 0777) or die "Can't shmget: $!";
+shmwrite($shmem_id, "wait", 0, $shmem_size) or die "Can't shmwrite: $!";
+
+my $psql_timeout = IPC::Run::timer($PostgreSQL::Test::Utils::timeout_default);
+#
+# Test set-up
+#
+my ($node, $result);
+$node = PostgreSQL::Test::Cluster->new('RC_test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->append_conf('postgresql.conf', 'fsync = off');
+$node->append_conf('postgresql.conf', 'autovacuum = off');
+$node->start;
+$node->safe_psql('postgres', q(CREATE UNLOGGED TABLE tbl(i int primary key, n int)));
+
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+# IT IS **REQUIRED** TO REPRODUCE THE ISSUE
+$node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i, n)));
+$node->safe_psql('postgres', q(INSERT INTO tbl VALUES(13,1)));
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+my $builder = Test::More->builder;
+$builder->use_numbers(0);
+$builder->no_plan();
+
+my $child  = $builder->child("pg_bench");
+
+if(!defined($pid = fork())) {
+	# fork returned undef, so unsuccessful
+	die "Cannot fork a child: $!";
+} elsif ($pid == 0) {
+
+	$pid = fork();
+	if ($pid == 0) {
+		$node->pgbench(
+			'--no-vacuum --client=30 -j 2 --transactions=1000000',
+			0,
+			[qr{actually processed}],
+			[qr{^$}],
+			'concurrent INSERTs, UPDATES and RC',
+			{
+				'002_pgbench_concurrent_transaction_updates' => q(
+					BEGIN;
+					INSERT INTO tbl VALUES(13,1) on conflict(i) do update set n = tbl.n + EXCLUDED.n;
+					COMMIT;
+				),
+			});
+
+		if ($child->is_passing()) {
+			shmwrite($shmem_id, "done", 0, $shmem_size) or die "Can't shmwrite: $!";
+		} else {
+			shmwrite($shmem_id, "fail", 0, $shmem_size) or die "Can't shmwrite: $!";
+		}
+
+		my $pg_bench_fork_flag;
+		while (1) {
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			sleep(0.1);
+			last if $pg_bench_fork_flag eq "stop";
+		}
+	}
+	else {
+		my ($result, $stdout, $stderr, $n, $prev_n, $pg_bench_fork_flag);
+		while (1) {
+			sleep(1);
+			$prev_n = $n;
+			($result, $n, $stderr) = $node->psql('postgres', q(SELECT n from tbl WHERE i = 13;));
+			diag(" current n is " . $n . ', ' . ($n - $prev_n) . ' per one second');
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			last if $pg_bench_fork_flag eq "stop";
+		}
+	}
+} else {
+	my $pg_bench_fork_flag;
+	shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+
+	subtest 'reindex run subtest' => sub {
+		is($pg_bench_fork_flag, "wait", "pg_bench_fork_flag is correct");
+
+		my %psql = (stdin => '', stdout => '', stderr => '');
+		$psql{run} = IPC::Run::start(
+			[ 'psql', '-XA', '-f', '-', '-d', $node->connstr('postgres') ],
+			'<',
+			\$psql{stdin},
+			'>',
+			\$psql{stdout},
+			'2>',
+			\$psql{stderr},
+			$psql_timeout);
+
+		my ($result, $stdout, $stderr, $n, $begin_time, $end_time, $before_reindex, $after_reindex);
+
+		# IT IS NOT REQUIRED, JUST FOR CONSISTENCY
+		($result, $stdout, $stderr) = $node->psql('postgres', q(ALTER TABLE tbl SET (parallel_workers=0);));
+		is($result, '0', 'ALTER TABLE is correct');
+
+		while (1)
+		{
+			my $sql = q(REINDEX INDEX CONCURRENTLY tbl_pkey;);
+
+			($result, $before_reindex, $stderr) = $node->psql('postgres', q(SELECT n from tbl WHERE i = 13;));
+
+			diag('going to start reindex, num tuples in table is ' . $before_reindex);
+			$begin_time = time();
+			($result, $stdout, $stderr) = $node->psql('postgres', $sql);
+			is($result, '0', 'REINDEX INDEX CONCURRENTLY is correct');
+
+			$end_time = time();
+			($result, $after_reindex, $stderr) = $node->psql('postgres', q(SELECT n from tbl WHERE i = 13;));
+			diag('reindex ' . $n++ . ' done in ' . ($end_time - $begin_time) . ' seconds, num inserted during reindex tuples is ' . (int($after_reindex) - int($before_reindex)) . ' speed is ' . ((int($after_reindex) - int($before_reindex)) / ($end_time - $begin_time)) . ' per second');
+
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			last if $pg_bench_fork_flag ne "wait";
+		}
+
+		# explicitly shut down psql instances gracefully
+		$psql{stdin} .= "\\q\n";
+		$psql{run}->finish;
+
+		is($pg_bench_fork_flag, "done", "pg_bench_fork_flag is correct");
+	};
+
+	$child->finalize();
+	$child->summary();
+	$node->stop;
+	done_testing();
+
+	shmwrite($shmem_id, "stop", 0, $shmem_size) or die "Can't shmwrite: $!";
+}
Index: src/backend/executor/execIndexing.c
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
--- a/src/backend/executor/execIndexing.c	(revision cb460d43c12db970056b2e994e023de06eabc494)
+++ b/src/backend/executor/execIndexing.c	(revision dd72fa154aed98254b47637fed62a1d584131dbf)
@@ -587,6 +587,13 @@
 							 indexRelation->rd_index->indexrelid))
 			continue;
 
+		if (!indexRelation->rd_index->indisvalid)
+			ereport(ERROR,
+					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+							errmsg("ON CONFLICT does not support invalid indexes as arbiters"),
+							errtableconstraint(heapRelation,
+											   RelationGetRelationName(indexRelation))));
+
 		if (!indexRelation->rd_index->indimmediate)
 			ereport(ERROR,
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

Subject: [PATCH] better test
error report in case of invalid index used as arbiter
test for issue with upsert fail
---
Index: src/test/modules/test_misc/t/006_concurrently_unique_fail.pl
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/test_misc/t/006_concurrently_unique_fail.pl b/src/test/modules/test_misc/t/006_concurrently_unique_fail.pl
new file mode 100644
--- /dev/null	(revision 5c5bcc5b7cc83381a6e479decd4252f3897b69bd)
+++ b/src/test/modules/test_misc/t/006_concurrently_unique_fail.pl	(revision 5c5bcc5b7cc83381a6e479decd4252f3897b69bd)
@@ -0,0 +1,44 @@
+
+# Copyright (c) 2024-2024, PostgreSQL Global Development Group
+
+# Test REINDEX INDEX CONCURRENTLY with concurrent INSERT
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my ($node, $result);
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('CIC_test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->start;
+$node->safe_psql('postgres', q(CREATE UNLOGGED TABLE tbl(i int primary key, updated_at timestamp)));
+
+$node->pgbench(
+		'--no-vacuum --client=2 -j 2 --transactions=1000',
+		0,
+		[qr{actually processed}],
+		[qr{^$}],
+		'concurrent INSERTs, UPDATES and RC',
+		{
+			'01_updates' => q(
+				INSERT INTO tbl VALUES(13,now()) ON CONFLICT(i) DO UPDATE SET updated_at = now();
+			),
+			'02_reindex' => q(
+				SELECT pg_try_advisory_lock(42)::integer AS gotlock \gset
+				\if :gotlock
+					REINDEX INDEX CONCURRENTLY tbl_pkey;
+					SELECT pg_advisory_unlock(42);
+				\endif
+			),
+		});
+$node->stop;
+done_testing();
\ No newline at end of file
Index: src/test/modules/test_misc/t/007_concurrently_unique_stuck.pl
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/test_misc/t/007_concurrently_unique_stuck.pl b/src/test/modules/test_misc/t/007_concurrently_unique_stuck.pl
new file mode 100644
--- /dev/null	(revision 9446f944b415306d9e5d5ab98f69938d8f5ee87f)
+++ b/src/test/modules/test_misc/t/007_concurrently_unique_stuck.pl	(revision 9446f944b415306d9e5d5ab98f69938d8f5ee87f)
@@ -0,0 +1,165 @@
+# Copyright (c) 2024, PostgreSQL Global Development Group
+
+# Test REINDEX CONCURRENTLY with concurrent modifications and HOT updates
+use strict;
+use warnings;
+
+use Config;
+use Errno;
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Time::HiRes qw(usleep);
+use IPC::SysV;
+use threads;
+use Time::HiRes qw( time );
+use Test::More;
+use Test::Builder;
+
+if ($@ || $windows_os)
+{
+	plan skip_all => 'Fork and shared memory are not supported by this platform';
+}
+
+my ($pid, $shmem_id, $shmem_key,  $shmem_size);
+eval 'sub IPC_CREAT {0001000}' unless defined &IPC_CREAT;
+$shmem_size = 4;
+$shmem_key = rand(1000000);
+$shmem_id = shmget($shmem_key, $shmem_size, &IPC_CREAT | 0777) or die "Can't shmget: $!";
+shmwrite($shmem_id, "wait", 0, $shmem_size) or die "Can't shmwrite: $!";
+
+my $psql_timeout = IPC::Run::timer($PostgreSQL::Test::Utils::timeout_default);
+#
+# Test set-up
+#
+my ($node, $result);
+$node = PostgreSQL::Test::Cluster->new('RC_test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->append_conf('postgresql.conf', 'fsync = off');
+$node->append_conf('postgresql.conf', 'autovacuum = off');
+$node->start;
+$node->safe_psql('postgres', q(CREATE UNLOGGED TABLE tbl(i int primary key, n int)));
+
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+# IT IS **REQUIRED** TO REPRODUCE THE ISSUE
+$node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i, n)));
+$node->safe_psql('postgres', q(INSERT INTO tbl VALUES(13,1)));
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+my $builder = Test::More->builder;
+$builder->use_numbers(0);
+$builder->no_plan();
+
+my $child  = $builder->child("pg_bench");
+
+if(!defined($pid = fork())) {
+	# fork returned undef, so unsuccessful
+	die "Cannot fork a child: $!";
+} elsif ($pid == 0) {
+
+	$pid = fork();
+	if ($pid == 0) {
+		$node->pgbench(
+			'--no-vacuum --client=30 -j 2 --transactions=1000000',
+			0,
+			[qr{actually processed}],
+			[qr{^$}],
+			'concurrent INSERTs, UPDATES and RC',
+			{
+				'002_pgbench_concurrent_transaction_updates' => q(
+					BEGIN;
+					INSERT INTO tbl VALUES(13,1) on conflict(i) do update set n = tbl.n + EXCLUDED.n;
+					COMMIT;
+				),
+			});
+
+		if ($child->is_passing()) {
+			shmwrite($shmem_id, "done", 0, $shmem_size) or die "Can't shmwrite: $!";
+		} else {
+			shmwrite($shmem_id, "fail", 0, $shmem_size) or die "Can't shmwrite: $!";
+		}
+
+		my $pg_bench_fork_flag;
+		while (1) {
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			sleep(0.1);
+			last if $pg_bench_fork_flag eq "stop";
+		}
+	}
+	else {
+		my ($result, $stdout, $stderr, $n, $prev_n, $pg_bench_fork_flag);
+		while (1) {
+			sleep(1);
+			$prev_n = $n;
+			($result, $n, $stderr) = $node->psql('postgres', q(SELECT n from tbl WHERE i = 13;));
+			diag(" current n is " . $n . ', ' . ($n - $prev_n) . ' per one second');
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			last if $pg_bench_fork_flag eq "stop";
+		}
+	}
+} else {
+	my $pg_bench_fork_flag;
+	shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+
+	subtest 'reindex run subtest' => sub {
+		is($pg_bench_fork_flag, "wait", "pg_bench_fork_flag is correct");
+
+		my %psql = (stdin => '', stdout => '', stderr => '');
+		$psql{run} = IPC::Run::start(
+			[ 'psql', '-XA', '-f', '-', '-d', $node->connstr('postgres') ],
+			'<',
+			\$psql{stdin},
+			'>',
+			\$psql{stdout},
+			'2>',
+			\$psql{stderr},
+			$psql_timeout);
+
+		my ($result, $stdout, $stderr, $n, $begin_time, $end_time, $before_reindex, $after_reindex);
+
+		# IT IS NOT REQUIRED, JUST FOR CONSISTENCY
+		($result, $stdout, $stderr) = $node->psql('postgres', q(ALTER TABLE tbl SET (parallel_workers=0);));
+		is($result, '0', 'ALTER TABLE is correct');
+
+		while (1)
+		{
+			my $sql = q(REINDEX INDEX CONCURRENTLY tbl_pkey;);
+
+			($result, $before_reindex, $stderr) = $node->psql('postgres', q(SELECT n from tbl WHERE i = 13;));
+
+			diag('going to start reindex, num tuples in table is ' . $before_reindex);
+			$begin_time = time();
+			($result, $stdout, $stderr) = $node->psql('postgres', $sql);
+			is($result, '0', 'REINDEX INDEX CONCURRENTLY is correct');
+
+			$end_time = time();
+			($result, $after_reindex, $stderr) = $node->psql('postgres', q(SELECT n from tbl WHERE i = 13;));
+			diag('reindex ' . $n++ . ' done in ' . ($end_time - $begin_time) . ' seconds, num inserted during reindex tuples is ' . (int($after_reindex) - int($before_reindex)) . ' speed is ' . ((int($after_reindex) - int($before_reindex)) / ($end_time - $begin_time)) . ' per second');
+
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			last if $pg_bench_fork_flag ne "wait";
+		}
+
+		# explicitly shut down psql instances gracefully
+		$psql{stdin} .= "\\q\n";
+		$psql{run}->finish;
+
+		is($pg_bench_fork_flag, "done", "pg_bench_fork_flag is correct");
+	};
+
+	$child->finalize();
+	$child->summary();
+	$node->stop;
+	done_testing();
+
+	shmwrite($shmem_id, "stop", 0, $shmem_size) or die "Can't shmwrite: $!";
+}
Index: src/backend/executor/execIndexing.c
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
--- a/src/backend/executor/execIndexing.c	(revision cb460d43c12db970056b2e994e023de06eabc494)
+++ b/src/backend/executor/execIndexing.c	(revision 5c5bcc5b7cc83381a6e479decd4252f3897b69bd)
@@ -587,6 +587,9 @@
 							 indexRelation->rd_index->indexrelid))
 			continue;
 
+		Assert(indexRelation->rd_index->indislive);
+		Assert(indexRelation->rd_index->indisvalid);
+
 		if (!indexRelation->rd_index->indimmediate)
 			ereport(ERROR,
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

diff --git a/src/test/modules/test_misc/t/009_cdic_concurrently_unique_fail.pl b/src/test/modules/test_misc/t/009_cdic_concurrently_unique_fail.pl
new file mode 100644
index 0000000000..bd37c797a3
--- /dev/null
+++ b/src/test/modules/test_misc/t/009_cdic_concurrently_unique_fail.pl
@@ -0,0 +1,46 @@
+
+# Copyright (c) 2024-2024, PostgreSQL Global Development Group
+
+# Test CREATE/DROP INDEX CONCURRENTLY with concurrent INSERT
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my ($node, $result);
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('CIC_test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->start;
+$node->safe_psql('postgres', q(CREATE UNLOGGED TABLE tbl(i int primary key, updated_at timestamp)));
+$node->safe_psql('postgres', q(CREATE UNIQUE INDEX tbl_pkey_2 ON tbl (i)));
+
+$node->pgbench(
+		'--no-vacuum --client=100 -j 2 --transactions=1000',
+		0,
+		[qr{actually processed}],
+		[qr{^$}],
+		'concurrent INSERTs, UPDATES and CIC/DIC',
+		{
+			'01_updates' => q(
+				INSERT INTO tbl VALUES(13,now()) ON CONFLICT(i) DO UPDATE SET updated_at = now();
+			),
+			'02_reindex' => q(
+				SELECT pg_try_advisory_lock(42)::integer AS gotlock \gset
+				\if :gotlock
+					DROP INDEX CONCURRENTLY tbl_pkey_2;
+					CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_2 ON tbl (i);
+					SELECT pg_advisory_unlock(42);
+				\endif
+			),
+		});
+$node->stop;
+done_testing();

From 6731d0a2df03eb291b05b5424f8e4aa63c2216ee Mon Sep 17 00:00:00 2001
From: nkey <nkey@toloka.ai>
Date: Sun, 4 Aug 2024 21:24:49 +0200
Subject: [PATCH v1] spec to reproduce issue with REINDEX CONCURRENTLY and
 INSERT ON CONFLICT UPDATE

---
 src/backend/commands/indexcmds.c              |   3 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   3 +
 src/test/modules/injection_points/Makefile    |   2 +-
 .../expected/reindex_concurrently_upsert.out  | 131 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   1 +
 .../specs/reindex_concurrently_upsert.spec    |  70 ++++++++++
 7 files changed, 211 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 2caab88aa5..9437654b11 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -69,6 +69,7 @@
 #include "utils/regproc.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /* non-export function prototypes */
@@ -4078,7 +4079,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap");
 	StartTransactionCommand();
 
 	/*
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index 9f05b3654c..1d451a329a 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -115,6 +115,7 @@
 #include "nodes/nodeFuncs.h"
 #include "storage/lmgr.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -901,6 +902,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict");
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 4913e49319..d91b0a1cc7 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -69,6 +69,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1085,6 +1086,8 @@ ExecInsert(ModifyTableContext *context,
 				}
 			}
 
+			INJECTION_POINT("exec_insert_before_insert_speculative");
+
 			/*
 			 * Before we start insertion proper, acquire our "speculative
 			 * insertion lock".  Others can use that to wait for us to decide
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 2ffd2f77ed..f8a2a7630d 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -9,7 +9,7 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = inplace
+ISOLATION = inplace reindex_concurrently_upsert
 
 # The injection points are cluster-wide, so disable installcheck
 NO_INSTALLCHECK = 1
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 0000000000..3e855e2223
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,131 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_s1 s1_s1 s4_s1 s2_s1 s4_s2 s4_s3
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_s1: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_s1: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_s1: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_s1: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_s2: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_s1: <... completed>
+step s4_s3: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_s1: <... completed>
+step s2_s1: <... completed>
+
+starting permutation: s3_s1 s2_s1 s4_s1 s1_s1 s4_s2 s4_s3
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_s1: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s2_s1: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_s1: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_s1: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_s2: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_s1: <... completed>
+step s4_s3: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_s1: <... completed>
+step s2_s1: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 3c23c14d81..7caa9769b2 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -40,6 +40,7 @@ tests += {
   'isolation': {
     'specs': [
       'inplace',
+      'reindex_concurrently_upsert',
     ],
   },
 }
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 0000000000..fcaee1a21c
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,70 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_s1	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_s1	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_s1		{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_s1		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+}
+step s4_s2		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_s3		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+
+permutation
+	s3_s1
+	s1_s1
+	s4_s1
+	s2_s1
+	s4_s2
+	s4_s3
+
+permutation
+	s3_s1
+	s2_s1
+	s4_s1
+	s1_s1
+	s4_s2
+	s4_s3
\ No newline at end of file
-- 
2.34.1

From e41389c4a873fbf7dd28907cb4624dffc56cb3d9 Mon Sep 17 00:00:00 2001
From: nkey <nkey@toloka.ai>
Date: Fri, 16 Aug 2024 11:19:37 +0200
Subject: [PATCH v2] specs to reproduce issues with CREATE INDEX/REINDEX
 CONCURRENTLY for UNIQUE indexes and INSERT ON CONFLICT UPDATE using injection
 points

---
 src/backend/commands/indexcmds.c              |   5 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   2 +-
 .../expected/index_concurrently_upsert.out    |  80 ++++++
 .../expected/reindex_concurrently_upsert.out  | 238 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   2 +
 .../specs/index_concurrently_upsert.spec      |  68 +++++
 .../specs/reindex_concurrently_upsert.spec    |  86 +++++++
 10 files changed, 486 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 2caab88aa5..822467bdd5 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -69,6 +69,7 @@
 #include "utils/regproc.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /* non-export function prototypes */
@@ -1775,6 +1776,7 @@ DefineIndex(Oid tableId,
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
+	INJECTION_POINT("define_index_before_set_valid");
 
 	/*
 	 * Index can now be marked valid -- update its pg_index entry
@@ -4078,7 +4080,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap");
 	StartTransactionCommand();
 
 	/*
@@ -4152,6 +4154,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead");
 
 	foreach(lc, indexIds)
 	{
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index 9f05b3654c..1d451a329a 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -115,6 +115,7 @@
 #include "nodes/nodeFuncs.h"
 #include "storage/lmgr.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -901,6 +902,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict");
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 4913e49319..65bc63c612 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -69,6 +69,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1084,6 +1085,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative");
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 7d2b34d4f2..3a7357a050 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -64,6 +64,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -426,6 +427,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end");
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 2ffd2f77ed..9777c48367 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -9,7 +9,7 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = inplace
+ISOLATION = inplace reindex_concurrently_upsert index_concurrently_upsert
 
 # The injection points are cluster-wide, so disable installcheck
 NO_INSTALLCHECK = 1
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 0000000000..f39a6d452a
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,80 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	SELECT injection_points_detach('define_index_before_set_valid');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: <... completed>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 0000000000..b7639ff7e6
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+step s2_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 3c23c14d81..f2aa60702b 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -40,6 +40,8 @@ tests += {
   'isolation': {
     'specs': [
       'inplace',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
     ],
   },
 }
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 0000000000..5d6aba9073
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,68 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	SELECT injection_points_detach('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 0000000000..c6ad2c4198
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,86 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s2_start_upsert
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.34.1

From 9a4d01018e21d491c967b3378e61abdb06f52c74 Mon Sep 17 00:00:00 2001
From: nkey <nkey@toloka.ai>
Date: Sat, 24 Aug 2024 14:04:02 +0200
Subject: [PATCH v3 2/4] Modify the infer_arbiter_indexes function to consider
 both indisvalid and indisready indexes. Ensure that at least one indisvalid
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 78a3cfafde..5ffc815ae4 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -720,6 +720,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -813,7 +814,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -835,10 +842,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -932,6 +938,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -939,7 +946,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.34.1

From c2566ce93a8e24410ae89c1838a57e310e33cf88 Mon Sep 17 00:00:00 2001
From: nkey <nkey@toloka.ai>
Date: Sat, 24 Aug 2024 13:44:32 +0200
Subject: [PATCH v3 1/4] Specs top reproduce the issues with CREATE INDEX
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON
 CONFLICT DO UPDATE. These tests reproduce different error cases related to
 "duplicate key value violates unique constraint" where this error should not
 occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   5 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    |  80 ++++++
 .../index_concurrently_upsert_predicate.out   |  80 ++++++
 .../expected/reindex_concurrently_upsert.out  | 238 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 238 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 238 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   5 +
 .../specs/index_concurrently_upsert.spec      |  68 +++++
 .../index_concurrently_upsert_predicate.spec  |  70 ++++++
 .../specs/reindex_concurrently_upsert.spec    |  86 +++++++
 ...dex_concurrently_upsert_on_constraint.spec |  86 +++++++
 ...index_concurrently_upsert_partitioned.spec |  88 +++++++
 16 files changed, 1294 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index c5a56c75f6..ed7ed0f640 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -69,6 +69,7 @@
 #include "utils/regproc.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /* non-export function prototypes */
@@ -1776,6 +1777,7 @@ DefineIndex(Oid tableId,
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
+	INJECTION_POINT("define_index_before_set_valid");
 
 	/*
 	 * Index can now be marked valid -- update its pg_index entry
@@ -4082,7 +4084,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap");
 	StartTransactionCommand();
 
 	/*
@@ -4156,6 +4158,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead");
 
 	foreach(lc, indexIds)
 	{
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index 403a3f4055..5f0957e53f 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -115,6 +115,7 @@
 #include "nodes/nodeFuncs.h"
 #include "storage/lmgr.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -906,6 +907,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict");
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 8bf4c80d4a..cdbf0b4d4f 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -69,6 +69,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1087,6 +1088,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative");
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 7d2b34d4f2..3a7357a050 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -64,6 +64,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -426,6 +427,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end");
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index ed28cd13a8..0d5005be1f 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -13,7 +13,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = inplace
+ISOLATION = inplace \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 0000000000..f39a6d452a
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,80 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	SELECT injection_points_detach('define_index_before_set_valid');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: <... completed>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 0000000000..014d94d7ec
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,80 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now(); <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	SELECT injection_points_detach('define_index_before_set_valid');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: <... completed>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 0000000000..b7639ff7e6
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+step s2_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 0000000000..dbbb9691cc
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+step s2_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 0000000000..b4cedf820c
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+step s2_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index c9e357f644..6391417f4b 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -42,6 +42,11 @@ tests += {
   'isolation': {
     'specs': [
       'inplace',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
   },
   'tap': {
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 0000000000..5d6aba9073
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,68 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	SELECT injection_points_detach('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 0000000000..2bc3cfd775
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,70 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	SELECT injection_points_detach('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 0000000000..c6ad2c4198
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,86 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s2_start_upsert
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 0000000000..fb030f8575
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,86 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s2_start_upsert
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 0000000000..efa55809ae
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,88 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s2_start_upsert
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.34.1

From fd2dad875688f2d8f465c4a689940edb1824c39d Mon Sep 17 00:00:00 2001
From: nkey <nkey@toloka.ai>
Date: Sat, 24 Aug 2024 14:33:47 +0200
Subject: [PATCH v3 3/4] Modify the infer_arbiter_indexes function to also look
 for indexes that match the specified named constraint to be used as arbiters.
 This ensures that the same set of arbiter indexes is used for all concurrent
 transactions in cases where REINDEX CONCURRENTLY processes an index used as a
 named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 5ffc815ae4..6712efe4dd 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -714,9 +714,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -755,8 +756,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -768,30 +769,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -840,26 +887,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/* Build BMS representation of plain (non expression) index attrs */
 		indexedAttrs = NULL;
 		for (natt = 0; natt < idxForm->indnkeyatts; natt++)
@@ -872,7 +916,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -880,6 +924,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -917,26 +965,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.34.1

From 0c51f52341205b52fefa2ce0e7f3513835abf49e Mon Sep 17 00:00:00 2001
From: nkey <nkey@toloka.ai>
Date: Sat, 24 Aug 2024 15:19:53 +0200
Subject: [PATCH v3 4/4] Modify the ExecInitPartitionInfo function to consider
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
 arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 7651886229..aeeee41d5f 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -483,6 +483,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -693,6 +735,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -703,23 +747,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.34.1

Subject: [PATCH] Stress test for issues form https://www.postgresql.org/message-id/flat/ZnoZ6GNwkJmq-gTh%40paquier.xyz#4d13f826fb1e62860cc3ae30067bd23a

To run: 

make -C src/test/modules/test_misc/ check PROVE_TESTS='t/007_*'
make -C src/test/modules/test_misc/ check PROVE_TESTS='t/008_*'
make -C src/test/modules/test_misc/ check PROVE_TESTS='t/009_*'
---
Index: src/test/modules/test_misc/t/007_concurrently_unique_deadlock.pl
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/test_misc/t/007_concurrently_unique_deadlock.pl b/src/test/modules/test_misc/t/007_concurrently_unique_deadlock.pl
new file mode 100644
--- /dev/null	(date 1724509948524)
+++ b/src/test/modules/test_misc/t/007_concurrently_unique_deadlock.pl	(date 1724509948524)
@@ -0,0 +1,163 @@
+# Copyright (c) 2024, PostgreSQL Global Development Group
+
+# Test REINDEX CONCURRENTLY with concurrent modifications and HOT updates
+use strict;
+use warnings;
+
+use Config;
+use Errno;
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Time::HiRes qw(usleep);
+use IPC::SysV;
+use threads;
+use Time::HiRes qw( time );
+use Test::More;
+use Test::Builder;
+
+if ($@ || $windows_os)
+{
+	plan skip_all => 'Fork and shared memory are not supported by this platform';
+}
+
+my ($pid, $shmem_id, $shmem_key,  $shmem_size);
+eval 'sub IPC_CREAT {0001000}' unless defined &IPC_CREAT;
+$shmem_size = 4;
+$shmem_key = rand(1000000);
+$shmem_id = shmget($shmem_key, $shmem_size, &IPC_CREAT | 0777) or die "Can't shmget: $!";
+shmwrite($shmem_id, "wait", 0, $shmem_size) or die "Can't shmwrite: $!";
+
+my $psql_timeout = IPC::Run::timer($PostgreSQL::Test::Utils::timeout_default);
+#
+# Test set-up
+#
+my ($node, $result);
+$node = PostgreSQL::Test::Cluster->new('RC_test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->append_conf('postgresql.conf', 'fsync = off');
+$node->append_conf('postgresql.conf', 'autovacuum = off');
+$node->start;
+$node->safe_psql('postgres', q(CREATE UNLOGGED TABLE tbl(i int primary key, n int)));
+
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+# IT IS **REQUIRED** TO REPRODUCE THE ISSUE
+$node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i, n)));
+$node->safe_psql('postgres', q(INSERT INTO tbl VALUES(13,1)));
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+my $builder = Test::More->builder;
+$builder->use_numbers(0);
+$builder->no_plan();
+
+my $child  = $builder->child("pg_bench");
+
+if(!defined($pid = fork())) {
+	# fork returned undef, so unsuccessful
+	die "Cannot fork a child: $!";
+} elsif ($pid == 0) {
+
+	$pid = fork();
+	if ($pid == 0) {
+		$node->pgbench(
+			'--no-vacuum --client=30 -j 2 --transactions=10000 --exit-on-abort --verbose-errors',
+			0,
+			[qr{actually processed}],
+			[qr{^$}],
+			'concurrent INSERTs, UPDATES and RC',
+			{
+				'002_pgbench_concurrent_transaction_updates' => q(
+					INSERT INTO tbl VALUES(13,1) on conflict(i) do update set n = tbl.n + EXCLUDED.n;
+				),
+			});
+
+		if ($child->is_passing()) {
+			shmwrite($shmem_id, "done", 0, $shmem_size) or die "Can't shmwrite: $!";
+		} else {
+			shmwrite($shmem_id, "fail", 0, $shmem_size) or die "Can't shmwrite: $!";
+		}
+
+		my $pg_bench_fork_flag;
+		while (1) {
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			sleep(0.1);
+			last if $pg_bench_fork_flag eq "stop";
+		}
+	}
+	else {
+		my ($result, $stdout, $stderr, $n, $prev_n, $pg_bench_fork_flag);
+		while (1) {
+			sleep(1);
+			$prev_n = $n;
+			($result, $n, $stderr) = $node->psql('postgres', q(SELECT n from tbl WHERE i = 13;));
+			diag(" current n is " . $n . ', ' . ($n - $prev_n) . ' per one second');
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			last if $pg_bench_fork_flag eq "stop";
+		}
+	}
+} else {
+	my $pg_bench_fork_flag;
+	shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+
+	subtest 'reindex run subtest' => sub {
+		is($pg_bench_fork_flag, "wait", "pg_bench_fork_flag is correct");
+
+		my %psql = (stdin => '', stdout => '', stderr => '');
+		$psql{run} = IPC::Run::start(
+			[ 'psql', '-XA', '-f', '-', '-d', $node->connstr('postgres') ],
+			'<',
+			\$psql{stdin},
+			'>',
+			\$psql{stdout},
+			'2>',
+			\$psql{stderr},
+			$psql_timeout);
+
+		my ($result, $stdout, $stderr, $n, $begin_time, $end_time, $before_reindex, $after_reindex);
+
+		# IT IS NOT REQUIRED, JUST FOR CONSISTENCY
+		($result, $stdout, $stderr) = $node->psql('postgres', q(ALTER TABLE tbl SET (parallel_workers=0);));
+		is($result, '0', 'ALTER TABLE is correct');
+
+		while (1)
+		{
+			my $sql = q(REINDEX INDEX CONCURRENTLY tbl_pkey;);
+
+			($result, $before_reindex, $stderr) = $node->psql('postgres', q(SELECT n from tbl WHERE i = 13;));
+
+			diag('going to start reindex, num tuples in table is ' . $before_reindex);
+			$begin_time = time();
+			($result, $stdout, $stderr) = $node->psql('postgres', $sql);
+			is($result, '0', 'REINDEX INDEX CONCURRENTLY is correct');
+
+			$end_time = time();
+			($result, $after_reindex, $stderr) = $node->psql('postgres', q(SELECT n from tbl WHERE i = 13;));
+			diag('reindex ' . $n++ . ' done in ' . ($end_time - $begin_time) . ' seconds, num inserted during reindex tuples is ' . (int($after_reindex) - int($before_reindex)) . ' speed is ' . ((int($after_reindex) - int($before_reindex)) / ($end_time - $begin_time)) . ' per second');
+
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			last if $pg_bench_fork_flag ne "wait";
+		}
+
+		# explicitly shut down psql instances gracefully
+		$psql{stdin} .= "\\q\n";
+		$psql{run}->finish;
+
+		is($pg_bench_fork_flag, "done", "pg_bench_fork_flag is correct");
+	};
+
+	$child->finalize();
+	$child->summary();
+	$node->stop;
+	done_testing();
+
+	shmwrite($shmem_id, "stop", 0, $shmem_size) or die "Can't shmwrite: $!";
+}
Index: src/test/modules/test_misc/t/009_concurrently_unique_fail_reindex.pl
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/test_misc/t/009_concurrently_unique_fail_reindex.pl b/src/test/modules/test_misc/t/009_concurrently_unique_fail_reindex.pl
new file mode 100644
--- /dev/null	(date 1724509958148)
+++ b/src/test/modules/test_misc/t/009_concurrently_unique_fail_reindex.pl	(date 1724509958148)
@@ -0,0 +1,152 @@
+
+# Copyright (c) 2024, PostgreSQL Global Development Group
+
+# Test REINDEX CONCURRENTLY with concurrent modifications and HOT updates
+use strict;
+use warnings;
+
+use Config;
+use Errno;
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Time::HiRes qw(usleep);
+use IPC::SysV;
+use threads;
+use Time::HiRes qw( time );
+use Test::More;
+use Test::Builder;
+
+if ($@ || $windows_os)
+{
+	plan skip_all => 'Fork and shared memory are not supported by this platform';
+}
+
+my ($pid, $shmem_id, $shmem_key,  $shmem_size);
+eval 'sub IPC_CREAT {0001000}' unless defined &IPC_CREAT;
+$shmem_size = 4;
+$shmem_key = rand(1000000);
+$shmem_id = shmget($shmem_key, $shmem_size, &IPC_CREAT | 0777) or die "Can't shmget: $!";
+shmwrite($shmem_id, "wait", 0, $shmem_size) or die "Can't shmwrite: $!";
+
+my $psql_timeout = IPC::Run::timer($PostgreSQL::Test::Utils::timeout_default);
+#
+# Test set-up
+#
+my ($node, $result);
+$node = PostgreSQL::Test::Cluster->new('RC_test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->append_conf('postgresql.conf', 'fsync = off');
+$node->append_conf('postgresql.conf', 'autovacuum = off');
+$node->start;
+$node->safe_psql('postgres', q(CREATE UNLOGGED TABLE tbl(i int primary key, updated_at timestamp)));
+
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+# IT IS NOT REQUIRED TO REPRODUCE THE ISSUE BUT MAKES IT TO HAPPEN FASTER
+$node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i, updated_at)));
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+my $builder = Test::More->builder;
+$builder->use_numbers(0);
+$builder->no_plan();
+
+my $child  = $builder->child("pg_bench");
+
+if(!defined($pid = fork())) {
+	# fork returned undef, so unsuccessful
+	die "Cannot fork a child: $!";
+} elsif ($pid == 0) {
+
+	$node->pgbench(
+		'--no-vacuum --client=20 -j 2 --transactions=10000 --exit-on-abort --verbose-errors',
+		0,
+		[qr{actually processed}],
+		[qr{^$}],
+		'concurrent INSERTs, UPDATES and RC',
+		{
+			# Ensure some HOT updates happen
+			'002_pgbench_concurrent_transaction_updates' => q(
+				INSERT INTO tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+			),
+			'003_pgbench_concurrent_transaction_updates' => q(
+				INSERT INTO tbl VALUES(42,now()) on conflict(i) do update set updated_at = now();
+			),
+			'004_pgbench_concurrent_transaction_updates' => q(
+				INSERT INTO tbl VALUES(69,now()) on conflict(i) do update set updated_at = now();
+			),
+		});
+
+	if ($child->is_passing()) {
+		shmwrite($shmem_id, "done", 0, $shmem_size) or die "Can't shmwrite: $!";
+	} else {
+		shmwrite($shmem_id, "fail", 0, $shmem_size) or die "Can't shmwrite: $!";
+	}
+
+	my $pg_bench_fork_flag;
+	while (1) {
+		shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+		sleep(0.1);
+		last if $pg_bench_fork_flag eq "stop";
+	}
+} else {
+	my $pg_bench_fork_flag;
+	shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+
+	subtest 'reindex run subtest' => sub {
+		is($pg_bench_fork_flag, "wait", "pg_bench_fork_flag is correct");
+
+		my %psql = (stdin => '', stdout => '', stderr => '');
+		$psql{run} = IPC::Run::start(
+			[ 'psql', '-XA', '-f', '-', '-d', $node->connstr('postgres') ],
+			'<',
+			\$psql{stdin},
+			'>',
+			\$psql{stdout},
+			'2>',
+			\$psql{stderr},
+			$psql_timeout);
+
+		my ($result, $stdout, $stderr, $n, $begin_time, $end_time);
+
+		# IT IS NOT REQUIRED, JUST FOR CONSISTENCY
+		($result, $stdout, $stderr) = $node->psql('postgres', q(ALTER TABLE tbl SET (parallel_workers=0);));
+		is($result, '0', 'ALTER TABLE is correct');
+
+		$begin_time = time();
+		while (1)
+		{
+			my $sql = q(REINDEX INDEX CONCURRENTLY tbl_pkey;);
+
+			($result, $stdout, $stderr) = $node->psql('postgres', $sql);
+			is($result, '0', 'REINDEX INDEX CONCURRENTLY is correct');
+
+			$end_time = time();
+			 diag('waiting, now is ' . $n++ . ', seconds passed : ' . int($end_time - $begin_time));
+
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			last if $pg_bench_fork_flag ne "wait";
+		}
+
+		# explicitly shut down psql instances gracefully
+		$psql{stdin} .= "\\q\n";
+		$psql{run}->finish;
+
+		is($pg_bench_fork_flag, "done", "pg_bench_fork_flag is correct");
+	};
+
+	$child->finalize();
+	$child->summary();
+	$node->stop;
+	done_testing();
+
+	shmwrite($shmem_id, "stop", 0, $shmem_size) or die "Can't shmwrite: $!";
+}
Index: src/test/modules/test_misc/t/008_concurrently_unique_fail_create_index.pl
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/test_misc/t/008_concurrently_unique_fail_create_index.pl b/src/test/modules/test_misc/t/008_concurrently_unique_fail_create_index.pl
new file mode 100644
--- /dev/null	(date 1724509958155)
+++ b/src/test/modules/test_misc/t/008_concurrently_unique_fail_create_index.pl	(date 1724509958155)
@@ -0,0 +1,162 @@
+
+# Copyright (c) 2024, PostgreSQL Global Development Group
+
+# Test REINDEX CONCURRENTLY with concurrent modifications and HOT updates
+use strict;
+use warnings;
+
+use Config;
+use Errno;
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Time::HiRes qw(usleep);
+use IPC::SysV;
+use threads;
+use Time::HiRes qw( time );
+use Test::More;
+use Test::Builder;
+
+if ($@ || $windows_os)
+{
+	plan skip_all => 'Fork and shared memory are not supported by this platform';
+}
+
+my ($pid, $shmem_id, $shmem_key,  $shmem_size);
+eval 'sub IPC_CREAT {0001000}' unless defined &IPC_CREAT;
+$shmem_size = 4;
+$shmem_key = rand(1000000);
+$shmem_id = shmget($shmem_key, $shmem_size, &IPC_CREAT | 0777) or die "Can't shmget: $!";
+shmwrite($shmem_id, "wait", 0, $shmem_size) or die "Can't shmwrite: $!";
+
+my $psql_timeout = IPC::Run::timer($PostgreSQL::Test::Utils::timeout_default);
+#
+# Test set-up
+#
+my ($node, $result);
+$node = PostgreSQL::Test::Cluster->new('RC_test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->append_conf('postgresql.conf', 'fsync = off');
+$node->append_conf('postgresql.conf', 'autovacuum = off');
+$node->start;
+$node->safe_psql('postgres', q(CREATE UNLOGGED TABLE tbl(i int primary key, updated_at timestamp)));
+
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+# IT IS NOT REQUIRED TO REPRODUCE THE ISSUE BUT MAKES IT TO HAPPEN FASTER
+$node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i, updated_at)));
+
+#######################################################################################################################
+#######################################################################################################################
+#######################################################################################################################
+
+my $builder = Test::More->builder;
+$builder->use_numbers(0);
+$builder->no_plan();
+
+my $child  = $builder->child("pg_bench");
+
+if(!defined($pid = fork())) {
+	# fork returned undef, so unsuccessful
+	die "Cannot fork a child: $!";
+} elsif ($pid == 0) {
+
+	$node->pgbench(
+		'--no-vacuum --client=20 -j 2 --transactions=10000 --exit-on-abort --verbose-errors',
+		0,
+		[qr{actually processed}],
+		[qr{^$}],
+		'concurrent INSERTs, UPDATES and RC',
+		{
+			# Ensure some HOT updates happen
+			'002_pgbench_concurrent_transaction_updates' => q(
+				BEGIN;
+				INSERT INTO tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+				COMMIT;
+			),
+			'003_pgbench_concurrent_transaction_updates' => q(
+				BEGIN;
+				INSERT INTO tbl VALUES(42,now()) on conflict(i) do update set updated_at = now();
+				COMMIT;
+			),
+			'004_pgbench_concurrent_transaction_updates' => q(
+				BEGIN;
+				INSERT INTO tbl VALUES(69,now()) on conflict(i) do update set updated_at = now();
+				COMMIT;
+			),
+		});
+
+	if ($child->is_passing()) {
+		shmwrite($shmem_id, "done", 0, $shmem_size) or die "Can't shmwrite: $!";
+	} else {
+		shmwrite($shmem_id, "fail", 0, $shmem_size) or die "Can't shmwrite: $!";
+	}
+
+	my $pg_bench_fork_flag;
+	while (1) {
+		shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+		sleep(0.1);
+		last if $pg_bench_fork_flag eq "stop";
+	}
+} else {
+	my $pg_bench_fork_flag;
+	shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+
+	subtest 'reindex run subtest' => sub {
+		is($pg_bench_fork_flag, "wait", "pg_bench_fork_flag is correct");
+
+		my %psql = (stdin => '', stdout => '', stderr => '');
+		$psql{run} = IPC::Run::start(
+			[ 'psql', '-XA', '-f', '-', '-d', $node->connstr('postgres') ],
+			'<',
+			\$psql{stdin},
+			'>',
+			\$psql{stdout},
+			'2>',
+			\$psql{stderr},
+			$psql_timeout);
+
+		my ($result, $stdout, $stderr, $n, $begin_time, $end_time);
+
+		# IT IS NOT REQUIRED, JUST FOR CONSISTENCY
+		($result, $stdout, $stderr) = $node->psql('postgres', q(ALTER TABLE tbl SET (parallel_workers=0);));
+		is($result, '0', 'ALTER TABLE is correct');
+
+		$begin_time = time();
+		while (1)
+		{
+			my $sql1 = q(CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey2 ON tbl(i););
+			my $sql2 = q(DROP INDEX CONCURRENTLY tbl_pkey2;);
+
+			($result, $stdout, $stderr) = $node->psql('postgres', $sql1);
+			is($result, '0', 'CREATE INDEX CONCURRENTLY is correct');
+
+			($result, $stdout, $stderr) = $node->psql('postgres', $sql2);
+			is($result, '0', 'DROP INDEX CONCURRENTLY is correct');
+
+			$end_time = time();
+			#diag('waiting, now is ' . $n++ . ', seconds passed : ' . int($end_time - $begin_time));
+
+			shmread($shmem_id, $pg_bench_fork_flag, 0, $shmem_size) or die "Can't shmread: $!";
+			last if $pg_bench_fork_flag ne "wait";
+		}
+
+		# explicitly shut down psql instances gracefully
+		$psql{stdin} .= "\\q\n";
+		$psql{run}->finish;
+
+		is($pg_bench_fork_flag, "done", "pg_bench_fork_flag is correct");
+	};
+
+	$child->finalize();
+	$child->summary();
+	$node->stop;
+	done_testing();
+
+	shmwrite($shmem_id, "stop", 0, $shmem_size) or die "Can't shmwrite: $!";
+}

From 9c85b499793e9a4bcbb55cc5d78cfeacab368b58 Mon Sep 17 00:00:00 2001
From: nkey <nkey@toloka.ai>
Date: Thu, 14 Nov 2024 22:36:26 +0100
Subject: [PATCH v4 2/4] Modify the infer_arbiter_indexes function to consider 
 both indisvalid and indisready indexes. Ensure that at least one indisvalid 
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 37b0ca2e43..c835813290 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -719,6 +719,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -812,7 +813,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -834,10 +841,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -938,6 +944,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -945,7 +952,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0

From 087a6ebaf196487668afef1387ce843de54d5a2d Mon Sep 17 00:00:00 2001
From: nkey <nkey@toloka.ai>
Date: Thu, 14 Nov 2024 22:41:00 +0100
Subject: [PATCH v4 4/4] Modify the ExecInitPartitionInfo function to consider 
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
  arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 7651886229..aeeee41d5f 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -483,6 +483,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -693,6 +735,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -703,23 +747,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.43.0

From b50d6e07fbd3ad7aa231b488c1ede72ac3985219 Mon Sep 17 00:00:00 2001
From: nkey <nkey@toloka.ai>
Date: Thu, 14 Nov 2024 22:35:49 +0100
Subject: [PATCH v4 1/4] Specs top reproduce the issues with CREATE INDEX 
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON 
 CONFLICT DO UPDATE. These tests reproduce different error cases related to 
 "duplicate key value violates unique constraint" where this error should not 
 occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   5 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    |  80 ++++++
 .../index_concurrently_upsert_predicate.out   |  80 ++++++
 .../expected/reindex_concurrently_upsert.out  | 238 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 238 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 238 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   5 +
 .../specs/index_concurrently_upsert.spec      |  68 +++++
 .../index_concurrently_upsert_predicate.spec  |  70 ++++++
 .../specs/reindex_concurrently_upsert.spec    |  86 +++++++
 ...dex_concurrently_upsert_on_constraint.spec |  86 +++++++
 ...index_concurrently_upsert_partitioned.spec |  88 +++++++
 16 files changed, 1294 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index d1134733c1..bb0ea67554 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -72,6 +72,7 @@
 #include "utils/regproc.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /* non-export function prototypes */
@@ -1769,6 +1770,7 @@ DefineIndex(Oid tableId,
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
+	INJECTION_POINT("define_index_before_set_valid");
 
 	/*
 	 * Updating pg_index might involve TOAST table access, so ensure we have a
@@ -4206,7 +4208,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap");
 	StartTransactionCommand();
 
 	/*
@@ -4288,6 +4290,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead");
 
 	foreach(lc, indexIds)
 	{
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index f9a2fac79e..5d04f18934 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -936,6 +937,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict");
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 1161520f76..23cf4c6b54 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -69,6 +69,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1087,6 +1088,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative");
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 7d2b34d4f2..3a7357a050 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -64,6 +64,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -426,6 +427,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end");
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 0753a9df58..f8f86e8f3b 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -13,7 +13,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points reindex_conc
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic inplace
+ISOLATION = basic inplace \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 0000000000..f39a6d452a
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,80 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	SELECT injection_points_detach('define_index_before_set_valid');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: <... completed>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 0000000000..014d94d7ec
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,80 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now(); <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	SELECT injection_points_detach('define_index_before_set_valid');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: <... completed>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 0000000000..b7639ff7e6
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+step s2_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 0000000000..dbbb9691cc
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+step s2_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 0000000000..b4cedf820c
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+step s2_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 58f1900115..eccc686b46 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -44,6 +44,11 @@ tests += {
     'specs': [
       'basic',
       'inplace',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
   },
   'tap': {
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 0000000000..5d6aba9073
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,68 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	SELECT injection_points_detach('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 0000000000..2bc3cfd775
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,70 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	SELECT injection_points_detach('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 0000000000..c6ad2c4198
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,86 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s2_start_upsert
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 0000000000..fb030f8575
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,86 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s2_start_upsert
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 0000000000..efa55809ae
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,88 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s2_start_upsert
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

From 39d5c287183c8baef57b3fc9a2fae537a6d4702e Mon Sep 17 00:00:00 2001
From: nkey <nkey@toloka.ai>
Date: Thu, 14 Nov 2024 22:37:30 +0100
Subject: [PATCH v4 3/4] Modify the infer_arbiter_indexes function to also look
  for indexes that match the specified named constraint to be used as
 arbiters.  This ensures that the same set of arbiter indexes is used for all
 concurrent  transactions in cases where REINDEX CONCURRENTLY processes an
 index used as a  named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index c835813290..5ffef4595e 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -713,9 +713,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -754,8 +755,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -767,30 +768,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -839,26 +886,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -878,7 +922,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -886,6 +930,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -923,26 +971,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.43.0

From e9a562587a509ace581d7ccf40eb41eb73b93b6f Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Sun, 24 Nov 2024 14:55:13 +0100
Subject: [PATCH v5 4/4] Modify the ExecInitPartitionInfo function to consider 
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
   arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 76518862291..aeeee41d5f1 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -483,6 +483,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -693,6 +735,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -703,23 +747,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.43.0

From e781488e7f6f7cd4be9b3b9582c1b9e32b3df946 Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Sun, 24 Nov 2024 14:45:41 +0100
Subject: [PATCH v5 1/4] Specs top reproduce the issues with CREATE INDEX
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON
 CONFLICT DO UPDATE. These tests reproduce different error cases related to
 "duplicate key value violates unique constraint" where this error should not
 occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   4 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    |  80 ++++++
 .../index_concurrently_upsert_predicate.out   |  80 ++++++
 .../expected/reindex_concurrently_upsert.out  | 238 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 238 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 238 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |  11 +
 .../specs/index_concurrently_upsert.spec      |  68 +++++
 .../index_concurrently_upsert_predicate.spec  |  70 ++++++
 .../specs/reindex_concurrently_upsert.spec    |  86 +++++++
 ...dex_concurrently_upsert_on_constraint.spec |  86 +++++++
 ...index_concurrently_upsert_partitioned.spec |  88 +++++++
 16 files changed, 1299 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index d1134733c17..8f48f14eddd 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1766,6 +1766,7 @@ DefineIndex(Oid tableId,
 	 * before the reference snap was taken, we have to wait out any
 	 * transactions that might have older snapshots.
 	 */
+	INJECTION_POINT("define_index_before_set_valid");
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
@@ -4206,7 +4207,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap");
 	StartTransactionCommand();
 
 	/*
@@ -4285,6 +4286,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * index_drop() for more details.
 	 */
 
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead");
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index f9a2fac79e4..5d04f189340 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -936,6 +937,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict");
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 1161520f76b..23cf4c6b540 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -69,6 +69,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1087,6 +1088,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative");
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 7d2b34d4f20..3a7357a050d 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -64,6 +64,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -426,6 +427,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end");
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 0753a9df58c..f8f86e8f3b6 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -13,7 +13,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points reindex_conc
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic inplace
+ISOLATION = basic inplace \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 00000000000..7f0659e8369
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,80 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: <... completed>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 00000000000..2300d5165e9
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,80 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now(); <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: <... completed>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 00000000000..24bbbcbdd88
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+step s2_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 00000000000..d1cfd1731c8
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+step s2_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 00000000000..c95ff264f12
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s2_start_upsert: INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+step s2_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 58f19001157..91fc8ce687f 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -44,7 +44,16 @@ tests += {
     'specs': [
       'basic',
       'inplace',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
+    # We waiting for all snapshots, so, avoid parallel test executions
+    'runningcheck-parallel': false,
   },
   'tap': {
     'env': {
@@ -53,5 +62,7 @@ tests += {
     'tests': [
       't/001_stats.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 00000000000..075450935b6
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,68 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 00000000000..70a27475e10
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,70 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 00000000000..38b86d84345
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,86 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s2_start_upsert
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 00000000000..7d8e371bb0a
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,86 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s2_start_upsert
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 00000000000..b9253463039
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,88 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{ INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now(); }
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s2_start_upsert
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

From 20f6ddb8c43463b0fc9ee47505a114fe44e6d4ff Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Sun, 24 Nov 2024 14:54:13 +0100
Subject: [PATCH v5 3/4] Modify the infer_arbiter_indexes function to also look
   for indexes that match the specified named constraint to be used as 
 arbiters.  This ensures that the same set of arbiter indexes is used for all 
 concurrent  transactions in cases where REINDEX CONCURRENTLY processes an 
 index used as a  named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index c835813290a..5ffef4595e2 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -713,9 +713,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -754,8 +755,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -767,30 +768,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -839,26 +886,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -878,7 +922,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -886,6 +930,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -923,26 +971,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.43.0

From ddfc5d199626759695f4d7f1fa78c58fafae5e54 Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Sun, 24 Nov 2024 14:49:35 +0100
Subject: [PATCH v5 2/4] Modify the infer_arbiter_indexes function to consider 
 both indisvalid and indisready indexes. Ensure that at least one indisvalid 
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 37b0ca2e439..c835813290a 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -719,6 +719,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -812,7 +813,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -834,10 +841,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -938,6 +944,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -945,7 +952,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0

From cb8129a5baf491a8b9e24df819ebc6cdf67a19b9 Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Sun, 24 Nov 2024 14:54:13 +0100
Subject: [PATCH v6 3/4] Modify the infer_arbiter_indexes function to also look
 for indexes that match the specified named constraint to be used as arbiters.
 This ensures that the same set of arbiter indexes is used for all concurrent
 transactions in cases where REINDEX CONCURRENTLY processes an index used as a
 named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 34f205109ae..f91203dd353 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -714,9 +714,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -755,8 +756,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -768,30 +769,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -840,26 +887,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -879,7 +923,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -887,6 +931,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -924,26 +972,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.43.0

From 066cde03a949b7951206dd2247ee607ab1192ceb Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Sun, 24 Nov 2024 14:45:41 +0100
Subject: [PATCH v6 1/4] Specs top reproduce the issues with CREATE INDEX
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON
 CONFLICT DO UPDATE. These tests reproduce different error cases related to
 "duplicate key value violates unique constraint" where this error should not
 occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   4 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    | 106 ++++++
 .../index_concurrently_upsert_predicate.out   | 106 ++++++
 .../expected/reindex_concurrently_upsert.out  | 316 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 316 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 316 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |  11 +
 .../specs/index_concurrently_upsert.spec      |  96 ++++++
 .../index_concurrently_upsert_predicate.spec  |  98 ++++++
 .../specs/reindex_concurrently_upsert.spec    | 114 +++++++
 ...dex_concurrently_upsert_on_constraint.spec | 115 +++++++
 ...index_concurrently_upsert_partitioned.spec | 116 +++++++
 16 files changed, 1726 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index d6e23caef17..0ff498c4e14 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1766,6 +1766,7 @@ DefineIndex(Oid tableId,
 	 * before the reference snap was taken, we have to wait out any
 	 * transactions that might have older snapshots.
 	 */
+	INJECTION_POINT("define_index_before_set_valid");
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
@@ -4206,7 +4207,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap");
 	StartTransactionCommand();
 
 	/*
@@ -4285,6 +4286,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * index_drop() for more details.
 	 */
 
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead");
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index 7c87f012c30..ae11c1dd463 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -936,6 +937,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict");
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 1af8c9caf6c..8a1a085b106 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -69,6 +69,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1087,6 +1088,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative");
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 8f1508b1ee2..3d018c3a1e8 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -64,6 +64,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -388,6 +389,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end");
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 0753a9df58c..f8f86e8f3b6 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -13,7 +13,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points reindex_conc
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic inplace
+ISOLATION = basic inplace \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 00000000000..4a65abbb55e
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,106 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	call raise_notice('wakeup before set valid done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set valid done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	call raise_notice('wakeup 1 done again');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done again
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: <... completed>
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 00000000000..7c7ddc7a7f6
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,106 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	call raise_notice('wakeup before set valid done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set valid done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	call raise_notice('wakeup 1 done again');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done again
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: <... completed>
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 00000000000..cb597620fe3
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,316 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before swap done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set dead done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before swap done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set dead done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before swap done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set dead done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 00000000000..b29caa94e50
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,316 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before swap done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set dead done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before swap done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set dead done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before swap done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set dead done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 00000000000..16aebaa2e12
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,316 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before swap done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set dead done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s2_start_upsert s4_wakeup_to_swap s1_start_upsert s4_wakeup_s1 s4_wakeup_s2 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before swap done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set dead done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before swap done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s2_start_upsert: 
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 1 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  upsert 1 done
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup before set dead done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+s4: NOTICE:  wakeup 2 done
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s2: NOTICE:  upsert 2 done
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 989b4db226b..428f1219349 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -44,7 +44,16 @@ tests += {
     'specs': [
       'basic',
       'inplace',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
+    # We waiting for all snapshots, so, avoid parallel test executions
+    'runningcheck-parallel': false,
   },
   'tap': {
     'env': {
@@ -53,5 +62,7 @@ tests += {
     'tests': [
       't/001_stats.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 00000000000..a33e3e40b41
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,96 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+
+	CREATE PROCEDURE raise_notice (s text) LANGUAGE plpgsql AS
+	$$
+	BEGIN
+		RAISE NOTICE '%', s;
+	END;
+	$$;
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+	DROP PROCEDURE raise_notice;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	call raise_notice('wakeup 1 done again');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	call raise_notice('wakeup before set valid done');
+}
+
+permutation
+	s3_start_create_index(s2_start_upsert notices 1)
+	s1_start_upsert(s2_start_upsert notices 1)
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 00000000000..5dc7a71d7d4
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,98 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+
+	CREATE PROCEDURE raise_notice (s text) LANGUAGE plpgsql AS
+	$$
+	BEGIN
+		RAISE NOTICE '%', s;
+	END;
+	$$;
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+	DROP PROCEDURE raise_notice;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+	call raise_notice('wakeup 1 done again');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+	call raise_notice('wakeup before set valid done');
+}
+
+permutation
+	s3_start_create_index(s2_start_upsert notices 1)
+	s1_start_upsert(s2_start_upsert notices 1)
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 00000000000..733a83c91d2
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,114 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+
+	CREATE PROCEDURE raise_notice (s text) LANGUAGE plpgsql AS
+	$$
+	BEGIN
+		RAISE NOTICE '%', s;
+	END;
+	$$;
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+	DROP PROCEDURE raise_notice;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+}
+
+permutation
+	s3_start_reindex(s2_start_upsert notices 1)
+	s1_start_upsert(s4_wakeup_s2 notices 1)
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert notices 1)
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert notices 1)
+	s2_start_upsert(s1_start_upsert notices 1)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s2_start_upsert notices 1)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert notices 1)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 00000000000..7181fee8031
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,115 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+
+	CREATE PROCEDURE raise_notice (s text) LANGUAGE plpgsql AS
+	$$
+	BEGIN
+		RAISE NOTICE '%', s;
+	END;
+	$$;
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+	DROP PROCEDURE raise_notice;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+}
+
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+}
+
+permutation
+	s3_start_reindex(s2_start_upsert notices 1)
+	s1_start_upsert(s4_wakeup_s2 notices 1)
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert notices 1)
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert notices 1)
+	s2_start_upsert(s1_start_upsert notices 1)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s2_start_upsert notices 1)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert notices 1)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 00000000000..d577889e9c9
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,116 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+
+	CREATE PROCEDURE raise_notice (s text) LANGUAGE plpgsql AS
+	$$
+	BEGIN
+		RAISE NOTICE '%', s;
+	END;
+	$$;
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+	DROP PROCEDURE raise_notice;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 1 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	DO $$
+	BEGIN
+		INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+		RAISE NOTICE 'upsert 2 done';
+	EXCEPTION WHEN OTHERS THEN
+		RAISE NOTICE '% %', SQLERRM, SQLSTATE;
+	END; $$
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+	call raise_notice('wakeup before swap done');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+	call raise_notice('wakeup 1 done');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+	call raise_notice('wakeup 2 done');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+	call raise_notice('wakeup before set dead done');
+}
+
+permutation
+	s3_start_reindex(s2_start_upsert notices 1)
+	s1_start_upsert(s4_wakeup_s2 notices 1)
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert notices 1)
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert notices 1)
+	s2_start_upsert(s1_start_upsert notices 1)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s4_wakeup_s1
+	s4_wakeup_s2
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s2_start_upsert notices 1)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert notices 1)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

From ca3c8144eec8c8cb8636a5c1c18190234ae4a96b Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Sun, 24 Nov 2024 14:55:13 +0100
Subject: [PATCH v6 4/4] Modify the ExecInitPartitionInfo function to consider
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
 arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 7e71d422a62..3922ae39681 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -483,6 +483,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -693,6 +735,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -703,23 +747,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.43.0

From 5792be833e4a8204962fbe24294ced6b8113d0a0 Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Sun, 24 Nov 2024 14:49:35 +0100
Subject: [PATCH v6 2/4] Modify the infer_arbiter_indexes function to consider
 both indisvalid and indisready indexes. Ensure that at least one indisvalid
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index b9759c31252..34f205109ae 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -720,6 +720,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -813,7 +814,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -835,10 +842,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -939,6 +945,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -946,7 +953,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0

From 73ee9ba10ed157365876e4ba1efa1d529f86b6f6 Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Fri, 17 Jan 2025 21:14:32 +0100
Subject: [PATCH v7 1/4] Specs top reproduce the issues with CREATE INDEX 
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON 
 CONFLICT DO UPDATE. These tests reproduce different error cases related to 
 "duplicate key value violates unique constraint" where this error should not 
 occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   4 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    |  84 ++++++
 .../index_concurrently_upsert_predicate.out   |  84 ++++++
 .../expected/reindex_concurrently_upsert.out  | 250 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 250 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 250 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |  11 +
 .../specs/index_concurrently_upsert.spec      |  72 +++++
 .../index_concurrently_upsert_predicate.spec  |  74 ++++++
 .../specs/reindex_concurrently_upsert.spec    |  90 +++++++
 ...dex_concurrently_upsert_on_constraint.spec |  91 +++++++
 ...index_concurrently_upsert_partitioned.spec |  92 +++++++
 16 files changed, 1364 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index d6e23caef17..0ff498c4e14 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1766,6 +1766,7 @@ DefineIndex(Oid tableId,
 	 * before the reference snap was taken, we have to wait out any
 	 * transactions that might have older snapshots.
 	 */
+	INJECTION_POINT("define_index_before_set_valid");
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
@@ -4206,7 +4207,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap");
 	StartTransactionCommand();
 
 	/*
@@ -4285,6 +4286,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * index_drop() for more details.
 	 */
 
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead");
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index 7c87f012c30..ae11c1dd463 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -936,6 +937,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict");
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 1af8c9caf6c..8a1a085b106 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -69,6 +69,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1087,6 +1088,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative");
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 8f1508b1ee2..3d018c3a1e8 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -64,6 +64,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -388,6 +389,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end");
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 0753a9df58c..f8f86e8f3b6 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -13,7 +13,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points reindex_conc
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic inplace
+ISOLATION = basic inplace \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 00000000000..e7612e065f4
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: 
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 00000000000..0ef2f3a681c
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 00000000000..1bd8041289e
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,250 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 00000000000..68288812de2
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,250 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 00000000000..f8c81e2bea2
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,250 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 989b4db226b..428f1219349 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -44,7 +44,16 @@ tests += {
     'specs': [
       'basic',
       'inplace',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
+    # We waiting for all snapshots, so, avoid parallel test executions
+    'runningcheck-parallel': false,
   },
   'tap': {
     'env': {
@@ -53,5 +62,7 @@ tests += {
     'tests': [
       't/001_stats.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 00000000000..473b0408f55
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,72 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 00000000000..c8644a82d57
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,74 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 00000000000..08d0deaf58b
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,90 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 00000000000..97622388e71
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,91 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 00000000000..41f10c8736d
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,92 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

From d5e3a336869ff2f0abe299440358c70a2c6a5d34 Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Fri, 17 Jan 2025 21:16:10 +0100
Subject: [PATCH v7 4/4] Modify the ExecInitPartitionInfo function to consider 
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
  arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 7e71d422a62..3922ae39681 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -483,6 +483,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -693,6 +735,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -703,23 +747,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.43.0

From 02cf315bb0bdb2784a311ea28c52f13d52e120c2 Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Fri, 17 Jan 2025 21:15:10 +0100
Subject: [PATCH v7 2/4] Modify the infer_arbiter_indexes function to consider 
 both indisvalid and indisready indexes. Ensure that at least one indisvalid 
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index f2d319101d3..a4c937da3d1 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -720,6 +720,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -813,7 +814,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -835,10 +842,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -939,6 +945,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -946,7 +953,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0

From 063d1e1ae4b9c77c2b8b580838e0ece0d2df7d1d Mon Sep 17 00:00:00 2001
From: nkey <michail.nikolaev@gmail.com>
Date: Fri, 17 Jan 2025 21:15:49 +0100
Subject: [PATCH v7 3/4] Modify the infer_arbiter_indexes function to also look
  for indexes that match the specified named constraint to be used as
 arbiters.  This ensures that the same set of arbiter indexes is used for all
 concurrent  transactions in cases where REINDEX CONCURRENTLY processes an
 index used as a  named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index a4c937da3d1..71b61b69c1f 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -714,9 +714,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -755,8 +756,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -768,30 +769,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -840,26 +887,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -879,7 +923,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -887,6 +931,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -924,26 +972,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.43.0

From 2db0af6a7b5ba485464ad5a59ce106a6e438d41a Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:58 +0300
Subject: [PATCH v8 2/4] Modify the infer_arbiter_indexes function to consider 
 both indisvalid and indisready indexes. Ensure that at least one indisvalid 
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 71abb01f655..b6b55b7cbff 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -720,6 +720,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -813,7 +814,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -835,10 +842,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -939,6 +945,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -946,7 +953,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0

From e7ad602f92185f373c3ab1af3baac9cee0416191 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:52:23 +0300
Subject: [PATCH v8 4/4] Modify the ExecInitPartitionInfo function to consider 
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
   arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index b6e89d0620d..50e58be657f 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -486,6 +486,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -696,6 +738,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -706,23 +750,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.43.0

From 0e0e528b92eb7d9cc68f7af05a6cc9b2a39297f2 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:10 +0300
Subject: [PATCH v8 1/4] Specs top reproduce the issues with CREATE INDEX 
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON 
 CONFLICT DO UPDATE. These tests reproduce different error cases related to 
 "duplicate key value violates unique constraint" where this error should not 
 occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   4 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    |  84 ++++++
 .../index_concurrently_upsert_predicate.out   |  84 ++++++
 .../expected/reindex_concurrently_upsert.out  | 250 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 250 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 250 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   8 +
 .../specs/index_concurrently_upsert.spec      |  72 +++++
 .../index_concurrently_upsert_predicate.spec  |  74 ++++++
 .../specs/reindex_concurrently_upsert.spec    |  90 +++++++
 ...dex_concurrently_upsert_on_constraint.spec |  91 +++++++
 ...index_concurrently_upsert_partitioned.spec |  92 +++++++
 16 files changed, 1361 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index f8d3ea820e1..47c509ceb3e 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1796,6 +1796,7 @@ DefineIndex(Oid tableId,
 	 * before the reference snap was taken, we have to wait out any
 	 * transactions that might have older snapshots.
 	 */
+	INJECTION_POINT("define_index_before_set_valid");
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
@@ -4201,7 +4202,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap");
 	StartTransactionCommand();
 
 	/*
@@ -4280,6 +4281,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * index_drop() for more details.
 	 */
 
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead");
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index 7c87f012c30..ae11c1dd463 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -936,6 +937,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict");
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index b0fe50075ad..d5ad73f6f69 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -69,6 +69,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1158,6 +1159,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative");
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 8f1508b1ee2..3d018c3a1e8 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -64,6 +64,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -388,6 +389,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end");
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index e680991f8d4..5aa53f03049 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -14,7 +14,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points hashagg reindex_conc
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic inplace syscache-update-pruned
+ISOLATION = basic inplace syscache-update-pruned \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 00000000000..e7612e065f4
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: 
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 00000000000..0ef2f3a681c
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 00000000000..1bd8041289e
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,250 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 00000000000..68288812de2
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,250 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 00000000000..f8c81e2bea2
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,250 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index d61149712fd..e1443664c70 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -47,8 +47,14 @@ tests += {
       'basic',
       'inplace',
       'syscache-update-pruned',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
     'runningcheck': false, # see syscache-update-pruned
+    'runningcheck-parallel': false, # We waiting for all snapshots, so, avoid parallel test executions
   },
   'tap': {
     'env': {
@@ -57,5 +63,7 @@ tests += {
     'tests': [
       't/001_stats.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 00000000000..473b0408f55
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,72 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 00000000000..c8644a82d57
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,74 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 00000000000..08d0deaf58b
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,90 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 00000000000..97622388e71
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,91 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 00000000000..41f10c8736d
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,92 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

From b813b41f58d4e5a97eba97d2bacfd34e280de271 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:51:19 +0300
Subject: [PATCH v8 3/4] Modify the infer_arbiter_indexes function to also look
   for indexes that match the specified named constraint to be used as 
 arbiters.  This ensures that the same set of arbiter indexes is used for all 
 concurrent  transactions in cases where REINDEX CONCURRENTLY processes an 
 index used as a  named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index b6b55b7cbff..af7586a428f 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -714,9 +714,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -755,8 +756,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -768,30 +769,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -840,26 +887,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -879,7 +923,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -887,6 +931,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -924,26 +972,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.43.0

From e9634bc128203f2f8f86249765ad9a945dfbb3de Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:52:23 +0300
Subject: [PATCH v9 4/4] Modify the ExecInitPartitionInfo function to consider
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
 arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 3f8a4cb5244..f1757d02f1c 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -487,6 +487,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -697,6 +739,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -707,23 +751,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
-		}
 
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
+		}
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.43.0

From ff3a8b82137723c025772051b65561d1bd469a54 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:10 +0300
Subject: [PATCH v9 1/4] Specs to reproduce the issues with CREATE INDEX
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON
 CONFLICT DO UPDATE. These tests reproduce different error cases related to
 "duplicate key value violates unique constraint" where this error should not
 occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on a partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   4 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    |  84 ++++++
 .../index_concurrently_upsert_predicate.out   |  84 ++++++
 .../expected/reindex_concurrently_upsert.out  | 250 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 250 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 250 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   8 +
 .../specs/index_concurrently_upsert.spec      |  72 +++++
 .../index_concurrently_upsert_predicate.spec  |  74 ++++++
 .../specs/reindex_concurrently_upsert.spec    |  90 +++++++
 ...dex_concurrently_upsert_on_constraint.spec |  91 +++++++
 ...index_concurrently_upsert_partitioned.spec |  92 +++++++
 16 files changed, 1361 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index d962fe392cd..0f75debe7f1 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1790,6 +1790,7 @@ DefineIndex(Oid tableId,
 	 * before the reference snap was taken, we have to wait out any
 	 * transactions that might have older snapshots.
 	 */
+	INJECTION_POINT("define_index_before_set_valid", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
@@ -4195,7 +4196,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap", NULL);
 	StartTransactionCommand();
 
 	/*
@@ -4274,6 +4275,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * index_drop() for more details.
 	 */
 
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index bdf862b2406..499cba145dd 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -942,6 +943,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict", NULL);
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 46d533b7288..566dbecb390 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -69,6 +69,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1178,6 +1179,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative", NULL);
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index ea35f30f494..ad440ff024c 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -123,6 +123,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -447,6 +448,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end", NULL);
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index e680991f8d4..5aa53f03049 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -14,7 +14,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points hashagg reindex_conc
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic inplace syscache-update-pruned
+ISOLATION = basic inplace syscache-update-pruned \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 00000000000..e7612e065f4
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: 
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 00000000000..0ef2f3a681c
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 00000000000..1bd8041289e
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,250 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 00000000000..68288812de2
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,250 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 00000000000..f8c81e2bea2
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,250 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1 s4_wakeup_to_set_dead
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_start_reindex s4_wakeup_to_swap s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index d61149712fd..e1443664c70 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -47,8 +47,14 @@ tests += {
       'basic',
       'inplace',
       'syscache-update-pruned',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
     'runningcheck': false, # see syscache-update-pruned
+    'runningcheck-parallel': false, # We waiting for all snapshots, so, avoid parallel test executions
   },
   'tap': {
     'env': {
@@ -57,5 +63,7 @@ tests += {
     'tests': [
       't/001_stats.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 00000000000..473b0408f55
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,72 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 00000000000..c8644a82d57
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,74 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 00000000000..08d0deaf58b
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,90 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 00000000000..97622388e71
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,91 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 00000000000..41f10c8736d
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,92 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+
+permutation
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s4_wakeup_to_swap
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

From ec818ec7d9e06239efe381df7ead72831b035eaf Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:58 +0300
Subject: [PATCH v9 2/4] Modify the infer_arbiter_indexes function to consider
 both indisvalid and indisready indexes. Ensure that at least one indisvalid
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 59233b64730..63f2c90340a 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -722,6 +722,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -815,7 +816,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -837,10 +844,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -941,6 +947,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -948,7 +955,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0

From 25b1a6a215434881effc5a3355397a446d2dcaf8 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:51:19 +0300
Subject: [PATCH v9 3/4] Modify the infer_arbiter_indexes function to also look
 for indexes that match the specified named constraint to be used as arbiters.
 This ensures that the same set of arbiter indexes is used for all concurrent
 transactions in cases where REINDEX CONCURRENTLY processes an index used as a
 named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 63f2c90340a..0c720e450e9 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -716,9 +716,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -757,8 +758,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -770,30 +771,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -842,26 +889,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -881,7 +925,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -889,6 +933,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -926,26 +974,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.43.0

From 24833f7a8336812a1bb0f0d8262732582b71c01b Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:58 +0300
Subject: [PATCH v10 2/4] Modify the infer_arbiter_indexes function to consider
 both indisvalid and indisready indexes. Ensure that at least one indisvalid
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index da5d901ec3c..d3f26396aef 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -809,6 +809,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -902,7 +903,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -924,10 +931,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -1028,6 +1034,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -1035,7 +1042,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0

From 8d836fbede940fb672a643966db0f6cf565ef0e0 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:52:23 +0300
Subject: [PATCH v10 4/4] Modify the ExecInitPartitionInfo function to consider
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
 arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 1f2da072632..f77fe42a2a9 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -490,6 +490,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -701,6 +743,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -711,23 +755,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.43.0

From d7a570ffa1426632f10f0e4126406541622002d5 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:10 +0300
Subject: [PATCH v10 1/4] Specs to reproduce the issues with CREATE INDEX
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON
 CONFLICT DO UPDATE. These tests reproduce different error cases related to
 "duplicate key value violates unique constraint" where this error should not
 occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on a partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   4 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    |  84 +++++++
 .../index_concurrently_upsert_predicate.out   |  84 +++++++
 .../expected/reindex_concurrently_upsert.out  | 232 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 232 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 232 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   8 +
 .../specs/index_concurrently_upsert.spec      |  72 ++++++
 .../index_concurrently_upsert_predicate.spec  |  74 ++++++
 .../specs/reindex_concurrently_upsert.spec    |  94 +++++++
 ...dex_concurrently_upsert_on_constraint.spec |  95 +++++++
 ...index_concurrently_upsert_partitioned.spec |  96 ++++++++
 16 files changed, 1319 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 5712fac3697..974243c5c60 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1789,6 +1789,7 @@ DefineIndex(Oid tableId,
 	 * before the reference snap was taken, we have to wait out any
 	 * transactions that might have older snapshots.
 	 */
+	INJECTION_POINT("define_index_before_set_valid", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
@@ -4228,7 +4229,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap", NULL);
 	StartTransactionCommand();
 
 	/*
@@ -4307,6 +4308,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * index_drop() for more details.
 	 */
 
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index ca33a854278..0edf54e852d 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -942,6 +943,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict", NULL);
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 4c5647ac38a..f6d2a6ede93 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -70,6 +70,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1179,6 +1180,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative", NULL);
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 65561cc6bc3..8e1a918f130 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -123,6 +123,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -458,6 +459,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end", NULL);
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index fc82cd67f6c..6a03024b5ce 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -14,7 +14,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points hashagg reindex_conc vacuum
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic inplace syscache-update-pruned
+ISOLATION = basic inplace syscache-update-pruned \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 00000000000..e7612e065f4
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: 
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 00000000000..0ef2f3a681c
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 00000000000..3a2292696f1
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 00000000000..fa898f2e21b
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 00000000000..d6340d60738
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 20390d6b4bf..c1d0b93a58a 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -48,8 +48,14 @@ tests += {
       'basic',
       'inplace',
       'syscache-update-pruned',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
     'runningcheck': false, # see syscache-update-pruned
+    'runningcheck-parallel': false, # We waiting for all snapshots, so, avoid parallel test executions
   },
   'tap': {
     'env': {
@@ -58,5 +64,7 @@ tests += {
     'tests': [
       't/001_stats.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 00000000000..473b0408f55
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,72 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 00000000000..c8644a82d57
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,74 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 00000000000..a4d1c1ea232
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,94 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 00000000000..82ee940cfa5
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,95 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 00000000000..322848c808b
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,96 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

From 3ef8d27719350e92203f11afc1d59780edd447ce Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:51:19 +0300
Subject: [PATCH v10 3/4] Modify the infer_arbiter_indexes function to also
 look for indexes that match the specified named constraint to be used as
 arbiters. This ensures that the same set of arbiter indexes is used for all
 concurrent transactions in cases where REINDEX CONCURRENTLY processes an
 index used as a named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index d3f26396aef..d0c4386f798 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -803,9 +803,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -844,8 +845,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -857,30 +858,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -929,26 +976,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -968,7 +1012,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -976,6 +1020,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -1013,26 +1061,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.43.0

From 0b2717f70e45899d43049f16cb74c8381ab9e2ec Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Tue, 28 Oct 2025 01:16:13 +0100
Subject: [PATCH v1] doc: Document potential failure scenarios for concurrent
 `INSERT ... ON CONFLICT` during CONCURRENTLY index operation on the same
 table.

Author: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/CANtu0ojXmqjmEzp-=aJSxjsdE76iAsRgHBoK0QtYHimb_mEfsg@mail.gmail.com
---
 doc/src/sgml/ref/create_index.sgml | 10 ++++++++++
 doc/src/sgml/ref/insert.sgml       | 17 +++++++++++++++++
 doc/src/sgml/ref/reindex.sgml      | 11 +++++++++++
 3 files changed, 38 insertions(+)

diff --git a/doc/src/sgml/ref/create_index.sgml b/doc/src/sgml/ref/create_index.sgml
index b9c679c41e8..5ae7f1a1520 100644
--- a/doc/src/sgml/ref/create_index.sgml
+++ b/doc/src/sgml/ref/create_index.sgml
@@ -707,6 +707,16 @@ Indexes:
     partitioned index is a metadata only operation.
    </para>
 
+   <warning>
+     <para>
+       While <command>CREATE INDEX CONCURRENTLY</command> is running on a unique
+       index, concurrent <command>INSERT ... ON CONFLICT</command> statement on
+       the same table that uses an index compatible with the index being built
+       may unexpectedly fail with duplicate key constraint violation error.
+       See <xref linkend="sql-on-conflict"/> for more details.
+     </para>
+   </warning>
+
   </refsect2>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 3f139917790..dc4b341ca3e 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -594,6 +594,23 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
     </para>
    </tip>
 
+   <warning>
+    <para>
+      If <command>CREATE INDEX CONCURRENTLY</command> or <command>REINDEX
+      CONCURRENTLY</command> is running on a unique index (or on a table
+      containing unique indexes), concurrent <command>INSERT ... ON CONFLICT</command>
+      statements on the same table may unexpectedly fail with duplicate key
+      constraint violation errors. This can occur when the statement uses an
+      index that is either compatible with the index being built or rebuilt,
+      or is itself being reindexed. Both <literal>DO UPDATE</literal> and
+      <literal>DO NOTHING</literal> conflict actions are affected.
+    </para>
+    <para>
+      These failures only occur during a brief window when the system catalogs
+      are being modified, not throughout the entire index build or rebuild process.
+    </para>
+   </warning>
+
   </refsect2>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/reindex.sgml b/doc/src/sgml/ref/reindex.sgml
index c4055397146..9b65b81615e 100644
--- a/doc/src/sgml/ref/reindex.sgml
+++ b/doc/src/sgml/ref/reindex.sgml
@@ -513,6 +513,17 @@ Indexes:
     in the <structname>pg_stat_progress_create_index</structname> view. See
     <xref linkend="create-index-progress-reporting"/> for details.
   </para>
+
+  <warning>
+    <para>
+      While <command>REINDEX CONCURRENTLY</command> is running on a unique
+      index or on a table containing unique indexes, concurrent
+      <command>INSERT ... ON CONFLICT</command> statement on the same table
+      that uses an index compatible with any of the indexes being rebuilt
+      may unexpectedly fail with duplicate key constraint violation errors.
+      See <xref linkend="sql-on-conflict"/> for more details.
+    </para>
+   </warning>
   </refsect2>
  </refsect1>
 
-- 
2.43.0

From: Noah Misch <noah@leadboat.com>

Doc: cover index CONCURRENTLY causing errors in INSERT ... ON CONFLICT.

Author: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/CANtu0ojXmqjmEzp-=aJSxjsdE76iAsRgHBoK0QtYHimb_mEfsg@mail.gmail.com
Backpatch-through: 13

diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 3f13991..f88ea78 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -594,6 +594,17 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
     </para>
    </tip>
 
+   <warning>
+    <para>
+      While <command>CREATE INDEX CONCURRENTLY</command> or <command>REINDEX
+      CONCURRENTLY</command> is running on a unique index, <command>INSERT
+      ... ON CONFLICT</command> statements on the same table may unexpectedly
+      fail with a unique violation.  Using <literal>ON CONFLICT ON
+      CONSTRAINT</literal> <replaceable class="parameter">
+      constraint_name</replaceable> avoids this, by disabling inference.
+    </para>
+   </warning>
+
   </refsect2>
  </refsect1>
 

From 1e4056a0766ad350b2c232dac6e85a6bb0a3456f Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:10 +0300
Subject: [PATCH v11 2/6] Specs to reproduce the issues with CREATE INDEX
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON
 CONFLICT DO UPDATE. These tests reproduce different error cases related to
 "duplicate key value violates unique constraint" where this error should not
 occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on a partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   4 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    |  84 +++++++
 .../index_concurrently_upsert_predicate.out   |  84 +++++++
 .../expected/reindex_concurrently_upsert.out  | 232 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 232 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 232 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   8 +
 .../specs/index_concurrently_upsert.spec      |  72 ++++++
 .../index_concurrently_upsert_predicate.spec  |  74 ++++++
 .../specs/reindex_concurrently_upsert.spec    |  94 +++++++
 ...dex_concurrently_upsert_on_constraint.spec |  95 +++++++
 ...index_concurrently_upsert_partitioned.spec |  96 ++++++++
 16 files changed, 1319 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 5712fac3697..974243c5c60 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1789,6 +1789,7 @@ DefineIndex(Oid tableId,
 	 * before the reference snap was taken, we have to wait out any
 	 * transactions that might have older snapshots.
 	 */
+	INJECTION_POINT("define_index_before_set_valid", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
@@ -4228,7 +4229,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap", NULL);
 	StartTransactionCommand();
 
 	/*
@@ -4307,6 +4308,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * index_drop() for more details.
 	 */
 
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index ca33a854278..0edf54e852d 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -942,6 +943,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict", NULL);
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 4c5647ac38a..f6d2a6ede93 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -70,6 +70,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1179,6 +1180,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative", NULL);
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 65561cc6bc3..8e1a918f130 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -123,6 +123,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -458,6 +459,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end", NULL);
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index fc82cd67f6c..6a03024b5ce 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -14,7 +14,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points hashagg reindex_conc vacuum
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic inplace syscache-update-pruned
+ISOLATION = basic inplace syscache-update-pruned \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 00000000000..e7612e065f4
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: 
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 00000000000..0ef2f3a681c
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 00000000000..3a2292696f1
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 00000000000..fa898f2e21b
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 00000000000..d6340d60738
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 20390d6b4bf..c1d0b93a58a 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -48,8 +48,14 @@ tests += {
       'basic',
       'inplace',
       'syscache-update-pruned',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
     'runningcheck': false, # see syscache-update-pruned
+    'runningcheck-parallel': false, # We waiting for all snapshots, so, avoid parallel test executions
   },
   'tap': {
     'env': {
@@ -58,5 +64,7 @@ tests += {
     'tests': [
       't/001_stats.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 00000000000..473b0408f55
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,72 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 00000000000..c8644a82d57
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,74 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 00000000000..a4d1c1ea232
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,94 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 00000000000..82ee940cfa5
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,95 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 00000000000..322848c808b
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,96 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

From 32ff7943bd411fde36906b7b2a941ac4aafa853d Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:52:23 +0300
Subject: [PATCH v11 5/6] Modify the ExecInitPartitionInfo function to consider
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
 arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 1f2da072632..f77fe42a2a9 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -490,6 +490,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -701,6 +743,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -711,23 +755,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.43.0

From 2b1320129a3687f3c2244e8b17da837a4bdf6ce1 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:58 +0300
Subject: [PATCH v11 3/6] Modify the infer_arbiter_indexes function to consider
 both indisvalid and indisready indexes. Ensure that at least one indisvalid
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 4b62a9756c1..b21e19290ab 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -814,6 +814,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -907,7 +908,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -929,10 +936,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -1033,6 +1039,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -1040,7 +1047,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0

From b62b94c0c51c310f4f237d78ef5db61cff77a501 Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Mon, 3 Nov 2025 20:34:33 +0100
Subject: [PATCH v11 6/6] Revert "Doc: cover index CONCURRENTLY causing errors
 in INSERT ... ON CONFLICT."

Issue fixed, this reverts commit 606df58881bfcdf50eea93d34308591bd3997fb5 with warnings.
---
 doc/src/sgml/ref/insert.sgml         | 9 ---------
 src/backend/optimizer/util/plancat.c | 5 -----
 2 files changed, 14 deletions(-)

diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index b337f2ee555..3f139917790 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -594,15 +594,6 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
     </para>
    </tip>
 
-   <warning>
-    <para>
-      While <command>CREATE INDEX CONCURRENTLY</command> or <command>REINDEX
-      CONCURRENTLY</command> is running on a unique index, <command>INSERT
-      ... ON CONFLICT</command> statements on the same table may unexpectedly
-      fail with a unique violation.
-    </para>
-   </warning>
-
   </refsect2>
  </refsect1>
 
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index d5f6ac8c16a..d0c4386f798 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -789,11 +789,6 @@ find_relation_notnullatts(PlannerInfo *root, Oid relid)
  * the purposes of inference.  If no opclass (or collation) is specified, then
  * all matching indexes (that may or may not match the default in terms of
  * each attribute opclass/collation) are used for inference.
- *
- * Note: during index CONCURRENTLY operations, different transactions
- * may reference different sets of arbiter indexes. This can lead to false
- * unique constraint violations that wouldn't occur during normal operations.
- * For more information, see insert.sgml.
  */
 List *
 infer_arbiter_indexes(PlannerInfo *root)
-- 
2.43.0

From 23e0efd495f0e2d3d719718d320bb551016dda65 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:51:19 +0300
Subject: [PATCH v11 4/6] Modify the infer_arbiter_indexes function to also
 look for indexes that match the specified named constraint to be used as
 arbiters. This ensures that the same set of arbiter indexes is used for all
 concurrent transactions in cases where REINDEX CONCURRENTLY processes an
 index used as a named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index b21e19290ab..d5f6ac8c16a 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -808,9 +808,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -849,8 +850,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -862,30 +863,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -934,26 +981,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -973,7 +1017,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -981,6 +1025,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -1018,26 +1066,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.43.0

From 606df58881bfcdf50eea93d34308591bd3997fb5 Mon Sep 17 00:00:00 2001
From: Noah Misch <noah@leadboat.com>
Date: Mon, 3 Nov 2025 20:19:10 +0100
Subject: [PATCH v11 1/6] Doc: cover index CONCURRENTLY causing errors in
 INSERT ... ON CONFLICT.

Author: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/CANtu0ojXmqjmEzp-=aJSxjsdE76iAsRgHBoK0QtYHimb_mEfsg@mail.gmail.com
Backpatch-through: 13
---
 doc/src/sgml/ref/insert.sgml         | 9 +++++++++
 src/backend/optimizer/util/plancat.c | 5 +++++
 2 files changed, 14 insertions(+)

diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 3f139917790..b337f2ee555 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -594,6 +594,15 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
     </para>
    </tip>
 
+   <warning>
+    <para>
+      While <command>CREATE INDEX CONCURRENTLY</command> or <command>REINDEX
+      CONCURRENTLY</command> is running on a unique index, <command>INSERT
+      ... ON CONFLICT</command> statements on the same table may unexpectedly
+      fail with a unique violation.
+    </para>
+   </warning>
+
   </refsect2>
  </refsect1>
 
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index da5d901ec3c..4b62a9756c1 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -789,6 +789,11 @@ find_relation_notnullatts(PlannerInfo *root, Oid relid)
  * the purposes of inference.  If no opclass (or collation) is specified, then
  * all matching indexes (that may or may not match the default in terms of
  * each attribute opclass/collation) are used for inference.
+ *
+ * Note: during index CONCURRENTLY operations, different transactions
+ * may reference different sets of arbiter indexes. This can lead to false
+ * unique constraint violations that wouldn't occur during normal operations.
+ * For more information, see insert.sgml.
  */
 List *
 infer_arbiter_indexes(PlannerInfo *root)
-- 
2.43.0

From 7ae8d431ec01c1c89a8de675dd05d036e37f714c Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:58 +0300
Subject: [PATCH v12 2/5] Modify the infer_arbiter_indexes function to consider
 both indisvalid and indisready indexes. Ensure that at least one indisvalid
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index d950bd93002..a8ae4401006 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -814,6 +814,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -907,7 +908,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * We need to consider both indisvalid and indisready indexes because
+		 * them may become indisvalid before execution phase. It is required
+		 * to keep set of indexes used as arbiter to be the same for all
+		 * concurrent transactions.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -929,10 +936,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -1033,6 +1039,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -1040,7 +1047,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0

From d2dd53972a6df00468248927b58d8d01d7e93673 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:52:23 +0300
Subject: [PATCH v12 4/5] Modify the ExecInitPartitionInfo function to consider
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
 arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index aa12e9ad2ea..066686483f0 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -490,6 +490,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -701,6 +743,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -711,23 +755,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.43.0

From 5bacecbc5bed4f6cd0eb6827c5c4e3c14692678e Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Sun, 9 Nov 2025 11:48:34 +0100
Subject: [PATCH v12 5/5] Revert "Doc: cover index CONCURRENTLY causing errors
 in INSERT ... ON CONFLICT."

This reverts commit 8b18ed6dfbb8b3e4483801b513fea6b429140569.
---
 doc/src/sgml/ref/insert.sgml         | 9 ---------
 src/backend/optimizer/util/plancat.c | 5 -----
 2 files changed, 14 deletions(-)

diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 0598b8dea34..04962e39e12 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -594,15 +594,6 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
     </para>
    </tip>
 
-   <warning>
-    <para>
-      While <command>CREATE INDEX CONCURRENTLY</command> or <command>REINDEX
-      CONCURRENTLY</command> is running on a unique index, <command>INSERT
-      ... ON CONFLICT</command> statements on the same table may unexpectedly
-      fail with a unique violation.
-    </para>
-   </warning>
-
   </refsect2>
  </refsect1>
 
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index ff416f0522c..02c732f8817 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -789,11 +789,6 @@ find_relation_notnullatts(PlannerInfo *root, Oid relid)
  * the purposes of inference.  If no opclass (or collation) is specified, then
  * all matching indexes (that may or may not match the default in terms of
  * each attribute opclass/collation) are used for inference.
- *
- * Note: during index CONCURRENTLY operations, different transactions may
- * reference different sets of arbiter indexes. This can lead to false unique
- * constraint violations that wouldn't occur during normal operations.  For
- * more information, see insert.sgml.
  */
 List *
 infer_arbiter_indexes(PlannerInfo *root)
-- 
2.43.0

From e81de553df67a38ae3710169700c0cdb542de73b Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:51:19 +0300
Subject: [PATCH v12 3/5] Modify the infer_arbiter_indexes function to also
 look for indexes that match the specified named constraint to be used as
 arbiters. This ensures that the same set of arbiter indexes is used for all
 concurrent transactions in cases where REINDEX CONCURRENTLY processes an
 index used as a named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index a8ae4401006..ff416f0522c 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -808,9 +808,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -849,8 +850,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -862,30 +863,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -934,26 +981,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -973,7 +1017,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -981,6 +1025,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -1018,26 +1066,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.43.0

From e9ca7ed8905d89350ee1af1459eb1f8f7fec3989 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:10 +0300
Subject: [PATCH v12 1/5] Specs to reproduce the issues with CREATE INDEX
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON
 CONFLICT DO UPDATE (8b18ed6dfbb8b3e4483801b513fea6b429140569).

These tests reproduce different error cases related to "duplicate key value violates unique constraint" where this error should not occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on a partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   4 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   2 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    |  84 +++++++
 .../index_concurrently_upsert_predicate.out   |  84 +++++++
 .../expected/reindex_concurrently_upsert.out  | 232 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 232 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 232 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   8 +
 .../specs/index_concurrently_upsert.spec      |  72 ++++++
 .../index_concurrently_upsert_predicate.spec  |  74 ++++++
 .../specs/reindex_concurrently_upsert.spec    |  94 +++++++
 ...dex_concurrently_upsert_on_constraint.spec |  95 +++++++
 ...index_concurrently_upsert_partitioned.spec |  96 ++++++++
 16 files changed, 1319 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 5712fac3697..974243c5c60 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1789,6 +1789,7 @@ DefineIndex(Oid tableId,
 	 * before the reference snap was taken, we have to wait out any
 	 * transactions that might have older snapshots.
 	 */
+	INJECTION_POINT("define_index_before_set_valid", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
@@ -4228,7 +4229,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap", NULL);
 	StartTransactionCommand();
 
 	/*
@@ -4307,6 +4308,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * index_drop() for more details.
 	 */
 
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index 401606f840a..df7e7bce86d 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -942,6 +943,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check_exclusion_or_unique_constraint_no_conflict", NULL);
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 4c5647ac38a..f6d2a6ede93 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -70,6 +70,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1179,6 +1180,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec_insert_before_insert_speculative", NULL);
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 65561cc6bc3..8e1a918f130 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -123,6 +123,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -458,6 +459,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("invalidate_catalog_snapshot_end", NULL);
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index fc82cd67f6c..6a03024b5ce 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -14,7 +14,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points hashagg reindex_conc vacuum
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic inplace syscache-update-pruned
+ISOLATION = basic inplace syscache-update-pruned \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 00000000000..e7612e065f4
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+step s1_start_upsert: 
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 00000000000..0ef2f3a681c
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,84 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 00000000000..3a2292696f1
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 00000000000..fa898f2e21b
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 00000000000..d6340d60738
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 20390d6b4bf..c1d0b93a58a 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -48,8 +48,14 @@ tests += {
       'basic',
       'inplace',
       'syscache-update-pruned',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
     'runningcheck': false, # see syscache-update-pruned
+    'runningcheck-parallel': false, # We waiting for all snapshots, so, avoid parallel test executions
   },
   'tap': {
     'env': {
@@ -58,5 +64,7 @@ tests += {
     'tests': [
       't/001_stats.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 00000000000..473b0408f55
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,72 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 00000000000..c8644a82d57
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,74 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+	SELECT injection_points_attach('invalidate_catalog_snapshot_end', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define_index_before_set_valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate_catalog_snapshot_end');
+	SELECT injection_points_wakeup('invalidate_catalog_snapshot_end');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define_index_before_set_valid');
+	SELECT injection_points_wakeup('define_index_before_set_valid');
+}
+
+permutation
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 00000000000..a4d1c1ea232
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,94 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 00000000000..82ee940cfa5
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,95 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 00000000000..322848c808b
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,96 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check_exclusion_or_unique_constraint_no_conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec_insert_before_insert_speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check_exclusion_or_unique_constraint_no_conflict');
+	SELECT injection_points_wakeup('check_exclusion_or_unique_constraint_no_conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec_insert_before_insert_speculative');
+	SELECT injection_points_wakeup('exec_insert_before_insert_speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

From d8ff71490497bea9d746daebeb95e3025df907f8 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:10 +0300
Subject: [PATCH v13 1/5] Specs to reproduce the issues with CREATE INDEX
 CONCURRENTLY and REINDEX CONCURRENTLY in scenarios involving INSERT ON
 CONFLICT DO UPDATE (8b18ed6dfbb8b3e4483801b513fea6b429140569).

These tests reproduce different error cases related to "duplicate key value violates unique constraint" where this error should not occur by design.

* REINDEX CONCURRENTLY and UPSERT with inferred index
* CREATE INDEX CONCURRENTLY and UPSERT with inferred indexes
* REINDEX CONCURRENTLY on a partitioned table
* REINDEX CONCURRENTLY with specified constraint name
* CREATE INDEX CONCURRENTLY with predicates

In each of these scenarios, the expected behavior is that the INSERT ON CONFLICT DO UPDATE should handle conflicts gracefully without raising a "duplicate key value violates unique constraint" error. However, due to the concurrent operations on the indexes, this error is encountered.
---
 src/backend/commands/indexcmds.c              |   4 +-
 src/backend/executor/execIndexing.c           |   3 +
 src/backend/executor/nodeModifyTable.c        |   2 +
 src/backend/utils/time/snapmgr.c              |   3 +
 src/test/modules/injection_points/Makefile    |   7 +-
 .../expected/index_concurrently_upsert.out    |  88 +++++++
 .../index_concurrently_upsert_predicate.out   |  88 +++++++
 .../expected/reindex_concurrently_upsert.out  | 232 ++++++++++++++++++
 ...ndex_concurrently_upsert_on_constraint.out | 232 ++++++++++++++++++
 ...eindex_concurrently_upsert_partitioned.out | 232 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   8 +
 .../specs/index_concurrently_upsert.spec      |  77 ++++++
 .../index_concurrently_upsert_predicate.spec  |  79 ++++++
 .../specs/reindex_concurrently_upsert.spec    |  94 +++++++
 ...dex_concurrently_upsert_on_constraint.spec |  95 +++++++
 ...index_concurrently_upsert_partitioned.spec |  96 ++++++++
 16 files changed, 1338 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
 create mode 100644 src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
 create mode 100644 src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 5712fac3697..316a94b59bc 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1789,6 +1789,7 @@ DefineIndex(Oid tableId,
 	 * before the reference snap was taken, we have to wait out any
 	 * transactions that might have older snapshots.
 	 */
+	INJECTION_POINT("define-index-before-set-valid", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_3);
 	WaitForOlderSnapshots(limitXmin, true);
@@ -4228,7 +4229,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * the same time to make sure we only get constraint violations from the
 	 * indexes with the correct names.
 	 */
-
+	INJECTION_POINT("reindex_relation_concurrently_before_swap", NULL);
 	StartTransactionCommand();
 
 	/*
@@ -4307,6 +4308,7 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 	 * index_drop() for more details.
 	 */
 
+	INJECTION_POINT("reindex_relation_concurrently_before_set_dead", NULL);
 	pgstat_progress_update_param(PROGRESS_CREATEIDX_PHASE,
 								 PROGRESS_CREATEIDX_PHASE_WAIT_4);
 	WaitForLockersMultiple(lockTags, AccessExclusiveLock, true);
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index 401606f840a..d973ecd8f8e 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -117,6 +117,7 @@
 #include "utils/multirangetypes.h"
 #include "utils/rangetypes.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 /* waitMode argument to check_exclusion_or_unique_constraint() */
 typedef enum
@@ -942,6 +943,8 @@ retry:
 	econtext->ecxt_scantuple = save_scantuple;
 
 	ExecDropSingleTupleTableSlot(existing_slot);
+	if (!conflict)
+		INJECTION_POINT("check-exclusion-or-unique-constraint-no-conflict", NULL);
 
 	return !conflict;
 }
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 4c5647ac38a..2f91a5912cf 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -70,6 +70,7 @@
 #include "utils/datum.h"
 #include "utils/rel.h"
 #include "utils/snapmgr.h"
+#include "utils/injection_point.h"
 
 
 typedef struct MTTargetRelLookup
@@ -1179,6 +1180,7 @@ ExecInsert(ModifyTableContext *context,
 					return NULL;
 				}
 			}
+			INJECTION_POINT("exec-insert-before-insert-speculative", NULL);
 
 			/*
 			 * Before we start insertion proper, acquire our "speculative
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 65561cc6bc3..e3bdabbe2f3 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -123,6 +123,7 @@
 #include "utils/resowner.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
+#include "utils/injection_point.h"
 
 
 /*
@@ -458,6 +459,8 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("pre-invalidate-catalog-snapshot-end", NULL);
+		INJECTION_POINT("invalidate-catalog-snapshot-end", NULL);
 	}
 }
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index fc82cd67f6c..6a03024b5ce 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -14,7 +14,12 @@ PGFILEDESC = "injection_points - facility for injection points"
 REGRESS = injection_points hashagg reindex_conc vacuum
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic inplace syscache-update-pruned
+ISOLATION = basic inplace syscache-update-pruned \
+			reindex_concurrently_upsert \
+			index_concurrently_upsert \
+			reindex_concurrently_upsert_partitioned \
+			reindex_concurrently_upsert_on_constraint \
+			index_concurrently_upsert_predicate
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert.out b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
new file mode 100644
index 00000000000..d26c3afc177
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert.out
@@ -0,0 +1,88 @@
+Parsed test spec with 5 sessions
+
+starting permutation: s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s5_noop:  <waiting ...>
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); <waiting ...>
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+step s1_start_upsert: 
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s5_noop: <... completed>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define-index-before-set-valid');
+	SELECT injection_points_wakeup('define-index-before-set-valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
+	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
new file mode 100644
index 00000000000..ed76de113ed
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index_concurrently_upsert_predicate.out
@@ -0,0 +1,88 @@
+Parsed test spec with 5 sessions
+
+starting permutation: s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s5_noop:  <waiting ...>
+step s3_start_create_index: CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000; <waiting ...>
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s5_noop: <... completed>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define-index-before-set-valid');
+	SELECT injection_points_wakeup('define-index-before-set-valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+ <waiting ...>
+step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
+	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
new file mode 100644
index 00000000000..f2ff16aff2a
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
new file mode 100644
index 00000000000..5bf1430ae10
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_on_constraint.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
new file mode 100644
index 00000000000..45ffdf94c1d
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex_concurrently_upsert_partitioned.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 20390d6b4bf..c1d0b93a58a 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -48,8 +48,14 @@ tests += {
       'basic',
       'inplace',
       'syscache-update-pruned',
+      'reindex_concurrently_upsert',
+      'index_concurrently_upsert',
+      'reindex_concurrently_upsert_partitioned',
+      'reindex_concurrently_upsert_on_constraint',
+      'index_concurrently_upsert_predicate',
     ],
     'runningcheck': false, # see syscache-update-pruned
+    'runningcheck-parallel': false, # We waiting for all snapshots, so, avoid parallel test executions
   },
   'tap': {
     'env': {
@@ -58,5 +64,7 @@ tests += {
     'tests': [
       't/001_stats.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
new file mode 100644
index 00000000000..01e0e4a5e3e
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert.spec
@@ -0,0 +1,77 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+	SELECT injection_points_attach('pre-invalidate-catalog-snapshot-end', 'notice');
+	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+}
+step s1_start_upsert	{
+    INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define-index-before-set-valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i); }
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define-index-before-set-valid');
+	SELECT injection_points_wakeup('define-index-before-set-valid');
+}
+
+session s5
+step s5_noop {}
+step s5_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
+	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+}
+
+permutation
+	s5_noop(s1_start_upsert notices 1)
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s5_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
new file mode 100644
index 00000000000..476e002cccb
--- /dev/null
+++ b/src/test/modules/injection_points/specs/index_concurrently_upsert_predicate.spec
@@ -0,0 +1,79 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: CREATE UNIQUE INDEX CONCURRENTLY
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+
+	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+	SELECT injection_points_attach('pre-invalidate-catalog-snapshot-end', 'notice');
+	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now())  on conflict(abs(i)) where i < 100 do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('define-index-before-set-valid', 'wait');
+}
+step s3_start_create_index		{ CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;}
+
+session s4
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+}
+step s4_wakeup_define_index_before_set_valid	{
+	SELECT injection_points_detach('define-index-before-set-valid');
+	SELECT injection_points_wakeup('define-index-before-set-valid');
+}
+
+session s5
+step s5_noop {}
+step s5_wakeup_s1_from_invalidate_catalog_snapshot	{
+	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
+	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+}
+
+permutation
+	s5_noop(s1_start_upsert notices 1)
+	s3_start_create_index(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_define_index_before_set_valid
+	s2_start_upsert(s1_start_upsert)
+	s5_wakeup_s1_from_invalidate_catalog_snapshot
+	s4_wakeup_s2
+	s4_wakeup_s1
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
new file mode 100644
index 00000000000..967033197ec
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert.spec
@@ -0,0 +1,94 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
new file mode 100644
index 00000000000..4defd6ccffe
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_on_constraint.spec
@@ -0,0 +1,95 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict on constraint tbl_pkey do update set updated_at = now();
+}
+
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
diff --git a/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
new file mode 100644
index 00000000000..8a2e172f3f1
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex_concurrently_upsert_partitioned.spec
@@ -0,0 +1,96 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_set_dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex_relation_concurrently_before_swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_swap');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex_relation_concurrently_before_set_dead');
+	SELECT injection_points_wakeup('reindex_relation_concurrently_before_set_dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

From 5bfac887269c239c91284b147dfb5ea80489c732 Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Sun, 9 Nov 2025 11:48:34 +0100
Subject: [PATCH v13 5/5] Revert "Doc: cover index CONCURRENTLY causing errors
 in INSERT ... ON CONFLICT."

This reverts commit 8b18ed6dfbb8b3e4483801b513fea6b429140569.
---
 doc/src/sgml/ref/insert.sgml         | 9 ---------
 src/backend/optimizer/util/plancat.c | 5 -----
 2 files changed, 14 deletions(-)

diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 0598b8dea34..04962e39e12 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -594,15 +594,6 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
     </para>
    </tip>
 
-   <warning>
-    <para>
-      While <command>CREATE INDEX CONCURRENTLY</command> or <command>REINDEX
-      CONCURRENTLY</command> is running on a unique index, <command>INSERT
-      ... ON CONFLICT</command> statements on the same table may unexpectedly
-      fail with a unique violation.
-    </para>
-   </warning>
-
   </refsect2>
  </refsect1>
 
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 4cb6eb9269c..08ae828e83b 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -789,11 +789,6 @@ find_relation_notnullatts(PlannerInfo *root, Oid relid)
  * the purposes of inference.  If no opclass (or collation) is specified, then
  * all matching indexes (that may or may not match the default in terms of
  * each attribute opclass/collation) are used for inference.
- *
- * Note: during index CONCURRENTLY operations, different transactions may
- * reference different sets of arbiter indexes. This can lead to false unique
- * constraint violations that wouldn't occur during normal operations.  For
- * more information, see insert.sgml.
  */
 List *
 infer_arbiter_indexes(PlannerInfo *root)
-- 
2.43.0

From 00c32a088c533f294eb927788e1f78750d2d34e6 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:51:19 +0300
Subject: [PATCH v13 3/5] Modify the infer_arbiter_indexes function to also
 look for indexes that match the specified named constraint to be used as
 arbiters. This ensures that the same set of arbiter indexes is used for all
 concurrent transactions in cases where REINDEX CONCURRENTLY processes an
 index used as a named constraint.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_on_constraint

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
---
 src/backend/optimizer/util/plancat.c | 121 +++++++++++++++++++--------
 1 file changed, 88 insertions(+), 33 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index f1ad164847d..4cb6eb9269c 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -808,9 +808,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 	List	   *indexList;
 	ListCell   *l;
 
-	/* Normalized inference attributes and inference expressions: */
-	Bitmapset  *inferAttrs = NULL;
-	List	   *inferElems = NIL;
+	/* Normalized required attributes and expressions: */
+	Bitmapset  *requiredArbiterAttrs = NULL;
+	List	   *requiredArbiterElems = NIL;
+	List	   *requiredIndexPredExprs = (List *) onconflict->arbiterWhere;
 
 	/* Results */
 	List	   *results = NIL;
@@ -849,8 +850,8 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
-			inferElems = lappend(inferElems, elem->expr);
+			/* If not a plain Var, just shove it in requiredArbiterElems for now */
+			requiredArbiterElems = lappend(requiredArbiterElems, elem->expr);
 			continue;
 		}
 
@@ -862,30 +863,76 @@ infer_arbiter_indexes(PlannerInfo *root)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("whole row unique index inference specifications are not supported")));
 
-		inferAttrs = bms_add_member(inferAttrs,
+		requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
 									attno - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	indexList = RelationGetIndexList(relation);
+
 	/*
 	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * because some additional sanity checks are required. Additionally, we
+	 * need to process other indexes as potential arbiters to account for
+	 * cases where REINDEX CONCURRENTLY is processing an index used as a
+	 * named constraint.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
 		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 
 		if (indexOidFromConstraint == InvalidOid)
+		{
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+					errmsg("constraint in ON CONFLICT clause has no associated index")));
+		}
+
+		/*
+		 * Find the named constraint index to extract its attributes and predicates.
+		 * We open all indexes in the loop to avoid deadlock of changed order of locks.
+		 * */
+		foreach(l, indexList)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	idxRel;
+			Form_pg_index idxForm;
+			AttrNumber	natt;
+
+			idxRel = index_open(indexoid, rte->rellockmode);
+			idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Prepare requirements for other indexes to be used as arbiter together
+					 * with indexOidFromConstraint. It is required to involve both equals indexes
+					 * in case of REINDEX CONCURRENTLY.
+					 */
+					for (natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno = idxRel->rd_index->indkey.values[natt];
+
+						if (attno != 0)
+							requiredArbiterAttrs = bms_add_member(requiredArbiterAttrs,
+														  attno - FirstLowInvalidHeapAttributeNumber);
+					}
+					requiredArbiterElems = RelationGetIndexExpressions(idxRel);
+					requiredIndexPredExprs = RelationGetIndexPredicate(idxRel);
+					/* We are done, so, quite the loop. */
+					index_close(idxRel, NoLock);
+					break;
+				}
+			}
+			index_close(idxRel, NoLock);
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
 	foreach(l, indexList)
 	{
 		Oid			indexoid = lfirst_oid(l);
@@ -943,26 +990,23 @@ infer_arbiter_indexes(PlannerInfo *root)
 				ereport(ERROR,
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
-
-			results = lappend_oid(results, idxForm->indexrelid);
-			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			goto found;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/* In the case of "ON constraint_name DO UPDATE" we need to skip non-unique candidates. */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				goto next;
+		}  else {
+			/*
+			 * Only considering conventional inference at this point (not named
+			 * constraints), so index under consideration can be immediately
+			 * skipped if it's not unique
+			 */
+			if (!idxForm->indisunique)
+				goto next;
 		}
 
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
-
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
@@ -982,7 +1026,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/* Non-expression attributes (if any) must match */
-		if (!bms_equal(indexedAttrs, inferAttrs))
+		if (!bms_equal(indexedAttrs, requiredArbiterAttrs))
 			goto next;
 
 		/* Expression attributes (if any) must match */
@@ -990,6 +1034,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
+		/*
+		 * If arbiterElems are present, check them. If name >constraint is
+		 * present arbiterElems == NIL.
+		 */
 		foreach(el, onconflict->arbiterElems)
 		{
 			InferenceElem *elem = (InferenceElem *) lfirst(el);
@@ -1027,26 +1075,33 @@ infer_arbiter_indexes(PlannerInfo *root)
 		}
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of the conventional inference involved ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In the case of named constraint ensure candidate has equal set
+		 * of expressions as the named constraint index.
 		 */
-		if (list_difference(idxExprs, inferElems) != NIL)
+		if (list_difference(idxExprs, requiredArbiterElems) != NIL)
 			goto next;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
+		/*
+		 * If it's a partial index and conventional inference, its predicate must be implied
+		 * by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid && !predicate_implied_by(predExprs, requiredIndexPredExprs, false))
+			goto next;
+		/* If it's a partial index and named constraint predicates must be equal. */
+		if (indexOidFromConstraint != InvalidOid && list_difference(predExprs, requiredIndexPredExprs) != NIL)
 			goto next;
 
+found:
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
 next:
-- 
2.43.0

From d1241cb9d5f4afa52b4ddf8abbc3ce5b125cdb7a Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:52:23 +0300
Subject: [PATCH v13 4/5] Modify the ExecInitPartitionInfo function to consider
 partitioned indexes that are potentially processed by REINDEX CONCURRENTLY as
 arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert_partitioned
---
 src/backend/executor/execPartition.c | 119 ++++++++++++++++++++++++---
 1 file changed, 107 insertions(+), 12 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index aa12e9ad2ea..066686483f0 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -490,6 +490,48 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int i;
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+	/* it is not supported for cases of exclusion constraints. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+	if (arbiterIndexRelation->rd_index->indnkeyatts != indexRelation->rd_index->indnkeyatts)
+		return false;
+
+	for (i = 0; i < indexRelation->rd_index->indnkeyatts; i++)
+	{
+		int			arbiterAttoNo = arbiterIndexRelation->rd_index->indkey.values[i];
+		int			attoNo = indexRelation->rd_index->indkey.values[i];
+		if (arbiterAttoNo != attoNo)
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -701,6 +743,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
 		{
 			List	   *childIdxs;
+			List 	   *nonAncestorIdxs = NIL;
+			int		   i, j, additional_arbiters = 0;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
@@ -711,23 +755,74 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, lfirst_oid(lc2)))
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxs = lappend_oid(nonAncestorIdxs, childIdx);
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxs)
+			{
+				for (i = 0; i < leaf_part_rri->ri_NumIndices; i++)
+				{
+					if (list_member_oid(nonAncestorIdxs, leaf_part_rri->ri_IndexRelationDescs[i]->rd_index->indexrelid))
+					{
+						Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[i];
+						IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[i];
+						Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+						/* It is too early to us non-ready indexes as arbiters */
+						if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+							continue;
+
+						for (j = 0; j < leaf_part_rri->ri_NumIndices; j++)
+						{
+							if (list_member_oid(arbiterIndexes,
+												leaf_part_rri->ri_IndexRelationDescs[j]->rd_index->indexrelid))
+							{
+								Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[j];
+								IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[j];
+
+								/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+								if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+															   nonAncestorIndexRelation, nonAncestorIndexInfo))
+								{
+									arbiterIndexes = lappend_oid(arbiterIndexes,
+																 nonAncestorIndexRelation->rd_index->indexrelid);
+									additional_arbiters++;
+								}
+							}
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxs);
+
+			/*
+			 * If the resulting lists are of inequal length, something is wrong.
+			 * (This shouldn't happen, since arbiter index selection should not
+			 * pick up a non-ready index.)
+			 *
+			 * But we need to consider an additional arbiter indexes also.
+			 */
+			if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
+				list_length(arbiterIndexes) - additional_arbiters)
+				elog(ERROR, "invalid arbiter index list");
 		}
-
-		/*
-		 * If the resulting lists are of inequal length, something is wrong.
-		 * (This shouldn't happen, since arbiter index selection should not
-		 * pick up an invalid index.)
-		 */
-		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
-			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
 		/*
-- 
2.43.0

From 384b38b86c412540a2f9471224273d24700e5b7a Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 20 Feb 2025 14:50:58 +0300
Subject: [PATCH v13 2/5] Modify the infer_arbiter_indexes function to consider
 both indisvalid and indisready indexes. Ensure that at least one indisvalid
 index is still required.

The change ensures that all concurrent transactions utilize the same set of indexes as arbiters. This uniformity is required to avoid conditions that could lead to "duplicate key value violates unique constraint" errors during UPSERT operations.

The patch resolves the issues in the following specs:
* reindex_concurrently_upsert
* index_concurrently_upsert
* index_concurrently_upsert_predicate

Despite the patch, the following specs are still affected:
* reindex_concurrently_upsert_partitioned
* reindex_concurrently_upsert_on_constraint
---
 src/backend/optimizer/util/plancat.c | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index d950bd93002..f1ad164847d 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -814,6 +814,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 	/* Results */
 	List	   *results = NIL;
+	bool	   foundValid = false;
 
 	/*
 	 * Quickly return NIL for ON CONFLICT DO NOTHING without an inference
@@ -907,7 +908,22 @@ infer_arbiter_indexes(PlannerInfo *root)
 		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
-		if (!idxForm->indisvalid)
+		/*
+		 * Ignore indexes that aren't indisready, because we cannot trust their
+		 * catalog structure yet.  However, if any indexes are marked
+		 * indisready but not yet indisvalid, we still consider them, because
+		 * they might turn valid while we're running.  Doing it this way
+		 * allows a concurrent transaction with a slightly later catalog
+		 * snapshot infer the same set of indexes, which is critical to
+		 * prevent spurious 'duplicate key' errors.
+		 *
+		 * However, another critical aspect is that a unique index that isn't
+		 * yet marked indisvalid=true might not be complete yet, meaning it
+		 * wouldn't detect possible duplicate rows.  In order to prevent false
+		 * negatives, we require that we include in the set of inferred indexes
+		 * at least one index that is marked valid.
+		 */
+		if (!idxForm->indisready)
 			goto next;
 
 		/*
@@ -929,10 +945,9 @@ infer_arbiter_indexes(PlannerInfo *root)
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
 			results = lappend_oid(results, idxForm->indexrelid);
-			list_free(indexList);
+			foundValid |= idxForm->indisvalid;
 			index_close(idxRel, NoLock);
-			table_close(relation, NoLock);
-			return results;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
@@ -1033,6 +1048,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			goto next;
 
 		results = lappend_oid(results, idxForm->indexrelid);
+		foundValid |= idxForm->indisvalid;
 next:
 		index_close(idxRel, NoLock);
 	}
@@ -1040,7 +1056,8 @@ next:
 	list_free(indexList);
 	table_close(relation, NoLock);
 
-	if (results == NIL)
+	/* It is required to have at least one indisvalid index during the planning. */
+	if (results == NIL || !foundValid)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
 				 errmsg("there is no unique or exclusion constraint matching the ON CONFLICT specification")));
-- 
2.43.0

From dede9ad2366fb4987af96a8dd4d6a33e9f832676 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Herrera?= <alvherre@kurilemu.de>
Date: Mon, 24 Nov 2025 18:46:24 +0100
Subject: [PATCH] Improve test case stability

Author: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
---
 src/backend/utils/time/snapmgr.c              |  1 +
 .../index-concurrently-upsert-predicate.out   | 11 +++++++---
 .../expected/index-concurrently-upsert.out    | 11 +++++++---
 .../index-concurrently-upsert-predicate.spec  | 21 ++++++++++++-------
 .../specs/index-concurrently-upsert.spec      | 19 +++++++++++------
 5 files changed, 44 insertions(+), 19 deletions(-)

diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 24f73a49d27..434abbf6b6f 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -459,6 +459,7 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
+		INJECTION_POINT("pre-invalidate-catalog-snapshot-end", NULL);
 		INJECTION_POINT("invalidate-catalog-snapshot-end", NULL);
 	}
 }
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
index af602bdc048..3d9512c8fc7 100644
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
+++ b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
@@ -1,6 +1,6 @@
-Parsed test spec with 4 sessions
+Parsed test spec with 5 sessions
 
-starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+starting permutation: s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
 injection_points_attach
 -----------------------
                        
@@ -16,12 +16,16 @@ injection_points_attach
                        
 (1 row)
 
+step s5_noop: 
+ <waiting ...>
 step s3_start_create_index: 
 	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
  <waiting ...>
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
 step s1_start_upsert: 
 	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
  <waiting ...>
+step s5_noop: <... completed>
 step s4_wakeup_define_index_before_set_valid: 
 	SELECT injection_points_detach('define-index-before-set-valid');
 	SELECT injection_points_wakeup('define-index-before-set-valid');
@@ -39,7 +43,7 @@ injection_points_wakeup
 step s2_start_upsert: 
 	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
  <waiting ...>
-step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
 	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
 	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
 
@@ -81,6 +85,7 @@ injection_points_wakeup
                        
 (1 row)
 
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
 step s1_start_upsert: <... completed>
 step s2_start_upsert: <... completed>
 step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert.out b/src/test/modules/injection_points/expected/index-concurrently-upsert.out
index eb6fd9592df..a9e8bb5d00e 100644
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert.out
+++ b/src/test/modules/injection_points/expected/index-concurrently-upsert.out
@@ -1,6 +1,6 @@
-Parsed test spec with 4 sessions
+Parsed test spec with 5 sessions
 
-starting permutation: s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s4_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+starting permutation: s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
 injection_points_attach
 -----------------------
                        
@@ -16,12 +16,16 @@ injection_points_attach
                        
 (1 row)
 
+step s5_noop: 
+ <waiting ...>
 step s3_start_create_index: 
 	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
  <waiting ...>
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
 step s1_start_upsert: 
     INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
  <waiting ...>
+step s5_noop: <... completed>
 step s4_wakeup_define_index_before_set_valid: 
 	SELECT injection_points_detach('define-index-before-set-valid');
 	SELECT injection_points_wakeup('define-index-before-set-valid');
@@ -39,7 +43,7 @@ injection_points_wakeup
 step s2_start_upsert: 
 	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
  <waiting ...>
-step s4_wakeup_s1_from_invalidate_catalog_snapshot: 
+step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
 	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
 	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
 
@@ -81,6 +85,7 @@ injection_points_wakeup
                        
 (1 row)
 
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
 step s1_start_upsert: <... completed>
 step s2_start_upsert: <... completed>
 step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec b/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
index 13897d88bce..725f6f22295 100644
--- a/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
+++ b/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
@@ -5,7 +5,7 @@
 # - s2: UPSERT the same tuple
 # - s3: CREATE UNIQUE INDEX CONCURRENTLY (with a predicate)
 #
-# - s4: control concurrency via injection points
+# - s4 and s5: control concurrency via injection points
 
 setup
 {
@@ -27,6 +27,7 @@ setup
 {
 	SELECT injection_points_set_local();
 	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+	SELECT injection_points_attach('pre-invalidate-catalog-snapshot-end', 'notice');
 	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
 }
 step s1_start_upsert
@@ -62,11 +63,6 @@ step s4_wakeup_s1
 	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
 	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
 }
-step s4_wakeup_s1_from_invalidate_catalog_snapshot
-{
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-}
 step s4_wakeup_s2
 {
 	SELECT injection_points_detach('exec-insert-before-insert-speculative');
@@ -78,11 +74,22 @@ step s4_wakeup_define_index_before_set_valid
 	SELECT injection_points_wakeup('define-index-before-set-valid');
 }
 
+session s5
+step s5_noop
+{
+}
+step s5_wakeup_s1_from_invalidate_catalog_snapshot
+{
+	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
+	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+}
+
 permutation
+	s5_noop(s1_start_upsert notices 1)
 	s3_start_create_index(s1_start_upsert, s2_start_upsert)
 	s1_start_upsert
 	s4_wakeup_define_index_before_set_valid
 	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s5_wakeup_s1_from_invalidate_catalog_snapshot
 	s4_wakeup_s2
 	s4_wakeup_s1
diff --git a/src/test/modules/injection_points/specs/index-concurrently-upsert.spec b/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
index b07a6408b3b..4487834aa8e 100644
--- a/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
+++ b/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
@@ -26,6 +26,7 @@ setup
 {
 	SELECT injection_points_set_local();
 	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+	SELECT injection_points_attach('pre-invalidate-catalog-snapshot-end', 'notice');
 	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
 }
 step s1_start_upsert
@@ -61,11 +62,6 @@ step s4_wakeup_s1
 	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
 	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
 }
-step s4_wakeup_s1_from_invalidate_catalog_snapshot
-{
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-}
 step s4_wakeup_s2
 {
 	SELECT injection_points_detach('exec-insert-before-insert-speculative');
@@ -77,11 +73,22 @@ step s4_wakeup_define_index_before_set_valid
 	SELECT injection_points_wakeup('define-index-before-set-valid');
 }
 
+session s5
+step s5_noop
+{
+}
+step s5_wakeup_s1_from_invalidate_catalog_snapshot
+{
+	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
+	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+}
+
 permutation
+	s5_noop(s1_start_upsert notices 1)
 	s3_start_create_index(s1_start_upsert, s2_start_upsert)
 	s1_start_upsert
 	s4_wakeup_define_index_before_set_valid
 	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1_from_invalidate_catalog_snapshot
+	s5_wakeup_s1_from_invalidate_catalog_snapshot
 	s4_wakeup_s2
 	s4_wakeup_s1
-- 
2.47.3

From 795427760facc8b3dcbeaa8a19bf0d237d3e630e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Herrera?= <alvherre@kurilemu.de>
Date: Wed, 26 Nov 2025 19:15:12 +0100
Subject: [PATCH] Fix new test for CATCACHE_FORCE_RELEASE builds

---
 .../index-concurrently-upsert-predicate.out   |  23 +++-
 .../index-concurrently-upsert-predicate_1.out | 116 ++++++++++++++++++
 .../expected/index-concurrently-upsert.out    |  23 +++-
 .../expected/index-concurrently-upsert_1.out  | 116 ++++++++++++++++++
 .../index-concurrently-upsert-predicate.spec  |  18 +++
 .../specs/index-concurrently-upsert.spec      |  18 +++
 6 files changed, 312 insertions(+), 2 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
 create mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert_1.out

diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
index 3d9512c8fc7..7adbab1c78e 100644
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
+++ b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
@@ -1,6 +1,6 @@
 Parsed test spec with 5 sessions
 
-starting permutation: s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
 injection_points_attach
 -----------------------
                        
@@ -16,6 +16,27 @@ injection_points_attach
                        
 (1 row)
 
+step s1_attach_invalidate_catalog_snapshot: 
+	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1_setup: 
+	select case when
+			(select pid from pg_stat_activity
+			      where wait_event_type = 'InjectionPoint' and
+			      wait_event = 'invalidate-catalog-snapshot-end') is not null
+			then injection_points_wakeup('invalidate-catalog-snapshot-end')
+		end;
+
+case
+----
+    
+(1 row)
+
 step s5_noop: 
  <waiting ...>
 step s3_start_create_index: 
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
new file mode 100644
index 00000000000..affc256ff82
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
@@ -0,0 +1,116 @@
+Parsed test spec with 5 sessions
+
+starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+step s1_attach_invalidate_catalog_snapshot: 
+	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+ <waiting ...>
+step s4_wakeup_s1_setup: 
+	select case when
+			(select pid from pg_stat_activity
+			      where wait_event_type = 'InjectionPoint' and
+			      wait_event = 'invalidate-catalog-snapshot-end') is not null
+			then injection_points_wakeup('invalidate-catalog-snapshot-end')
+		end;
+
+case
+----
+    
+(1 row)
+
+step s1_attach_invalidate_catalog_snapshot: <... completed>
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s5_noop: 
+ <waiting ...>
+step s3_start_create_index: 
+	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
+ <waiting ...>
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s5_noop: <... completed>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define-index-before-set-valid');
+	SELECT injection_points_wakeup('define-index-before-set-valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
+	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert.out b/src/test/modules/injection_points/expected/index-concurrently-upsert.out
index a9e8bb5d00e..cf961378942 100644
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert.out
+++ b/src/test/modules/injection_points/expected/index-concurrently-upsert.out
@@ -1,6 +1,6 @@
 Parsed test spec with 5 sessions
 
-starting permutation: s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
 injection_points_attach
 -----------------------
                        
@@ -16,6 +16,27 @@ injection_points_attach
                        
 (1 row)
 
+step s1_attach_invalidate_catalog_snapshot: 
+	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1_setup: 
+	select case when
+			(select pid from pg_stat_activity
+			      where wait_event_type = 'InjectionPoint' and
+			      wait_event = 'invalidate-catalog-snapshot-end') is not null
+			then injection_points_wakeup('invalidate-catalog-snapshot-end')
+		end;
+
+case
+----
+    
+(1 row)
+
 step s5_noop: 
  <waiting ...>
 step s3_start_create_index: 
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out b/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
new file mode 100644
index 00000000000..7a77830d56c
--- /dev/null
+++ b/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
@@ -0,0 +1,116 @@
+Parsed test spec with 5 sessions
+
+starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+step s1_attach_invalidate_catalog_snapshot: 
+	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+ <waiting ...>
+step s4_wakeup_s1_setup: 
+	select case when
+			(select pid from pg_stat_activity
+			      where wait_event_type = 'InjectionPoint' and
+			      wait_event = 'invalidate-catalog-snapshot-end') is not null
+			then injection_points_wakeup('invalidate-catalog-snapshot-end')
+		end;
+
+case
+----
+    
+(1 row)
+
+step s1_attach_invalidate_catalog_snapshot: <... completed>
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s5_noop: 
+ <waiting ...>
+step s3_start_create_index: 
+	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
+ <waiting ...>
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+step s1_start_upsert: 
+    INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s5_noop: <... completed>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define-index-before-set-valid');
+	SELECT injection_points_wakeup('define-index-before-set-valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
+	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
+	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec b/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
index 725f6f22295..e65e4a9120c 100644
--- a/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
+++ b/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
@@ -28,6 +28,9 @@ setup
 	SELECT injection_points_set_local();
 	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 	SELECT injection_points_attach('pre-invalidate-catalog-snapshot-end', 'notice');
+}
+step s1_attach_invalidate_catalog_snapshot
+{
 	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
 }
 step s1_start_upsert
@@ -58,6 +61,19 @@ step s3_start_create_index
 }
 
 session s4
+# Step s1_attach_invalidate_catalog_snapshot sleeps or not depending on
+# build conditions (CATCACHE_FORCE_RELEASE). Here we send a wakeup signal if
+# it's sleeping or do nothing otherwise, and print a null value in either
+# case.
+step s4_wakeup_s1_setup
+{
+	select case when
+			(select pid from pg_stat_activity
+			      where wait_event_type = 'InjectionPoint' and
+			      wait_event = 'invalidate-catalog-snapshot-end') is not null
+			then injection_points_wakeup('invalidate-catalog-snapshot-end')
+		end;
+}
 step s4_wakeup_s1
 {
 	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
@@ -85,6 +101,8 @@ step s5_wakeup_s1_from_invalidate_catalog_snapshot
 }
 
 permutation
+	s1_attach_invalidate_catalog_snapshot
+	s4_wakeup_s1_setup
 	s5_noop(s1_start_upsert notices 1)
 	s3_start_create_index(s1_start_upsert, s2_start_upsert)
 	s1_start_upsert
diff --git a/src/test/modules/injection_points/specs/index-concurrently-upsert.spec b/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
index 4487834aa8e..f78ed16c4f3 100644
--- a/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
+++ b/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
@@ -27,6 +27,9 @@ setup
 	SELECT injection_points_set_local();
 	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 	SELECT injection_points_attach('pre-invalidate-catalog-snapshot-end', 'notice');
+}
+step s1_attach_invalidate_catalog_snapshot
+{
 	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
 }
 step s1_start_upsert
@@ -57,6 +60,19 @@ step s3_start_create_index
 }
 
 session s4
+# Step s1_attach_invalidate_catalog_snapshot sleeps or not depending on
+# build conditions (CATCACHE_FORCE_RELEASE). Here we send a wakeup signal if
+# it's sleeping or do nothing otherwise, and print a null value in either
+# case.
+step s4_wakeup_s1_setup
+{
+	select case when
+			(select pid from pg_stat_activity
+			      where wait_event_type = 'InjectionPoint' and
+			      wait_event = 'invalidate-catalog-snapshot-end') is not null
+			then injection_points_wakeup('invalidate-catalog-snapshot-end')
+		end;
+}
 step s4_wakeup_s1
 {
 	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
@@ -84,6 +100,8 @@ step s5_wakeup_s1_from_invalidate_catalog_snapshot
 }
 
 permutation
+	s1_attach_invalidate_catalog_snapshot
+	s4_wakeup_s1_setup
 	s5_noop(s1_start_upsert notices 1)
 	s3_start_create_index(s1_start_upsert, s2_start_upsert)
 	s1_start_upsert
-- 
2.47.3

From 6b7626dc756125bb2792668185fb1bba01090aea Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Herrera?= <alvherre@kurilemu.de>
Date: Fri, 28 Nov 2025 18:09:40 +0100
Subject: [PATCH v14] ON CONFLICT: Consider indexes matching constraint index
 during REINDEX CONCURRENTLY
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This ensures that all transactions doing INSERT ON CONFLICT consider the
same set of indexes during the reindex operation, avoiding spurious
errors about duplicate insertions.

Author: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Discussion: https://postgr.es/m/CANtu0ojXmqjmEzp-=aJSxjsdE76iAsRgHBoK0QtYHimb_mEfsg@mail.gmail.com
---
 src/backend/optimizer/util/plancat.c          | 192 ++++++++++----
 src/backend/parser/parse_clause.c             |  16 +-
 src/test/modules/injection_points/Makefile    |   1 +
 ...ndex-concurrently-upsert-on-constraint.out | 238 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   1 +
 ...dex-concurrently-upsert-on-constraint.spec | 110 ++++++++
 6 files changed, 506 insertions(+), 52 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out
 create mode 100644 src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 7af9a2064e3..daf75612333 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -806,9 +806,15 @@ infer_arbiter_indexes(PlannerInfo *root)
 	Relation	relation;
 	Oid			indexOidFromConstraint = InvalidOid;
 	List	   *indexList;
-	ListCell   *l;
+	List	   *indexRelList = NIL;
 
-	/* Normalized inference attributes and inference expressions: */
+	/*
+	 * Required attributes and expressions used to match indexes to the clause
+	 * given by the user.  In the case where ON CONFLICT ON CONSTRAINT was
+	 * given, we need to compute these things to match other indexes, to
+	 * account for the case where the index is under REINDEX CONCURRENTLY.
+	 */
+	List	   *inferIndexExprs = (List *) onconflict->arbiterWhere;
 	Bitmapset  *inferAttrs = NULL;
 	List	   *inferElems = NIL;
 
@@ -841,15 +847,19 @@ infer_arbiter_indexes(PlannerInfo *root)
 	 * well as a separate list of expression items.  This simplifies matching
 	 * the cataloged definition of indexes.
 	 */
-	foreach(l, onconflict->arbiterElems)
+	foreach_ptr(InferenceElem, elem, onconflict->arbiterElems)
 	{
-		InferenceElem *elem = (InferenceElem *) lfirst(l);
 		Var		   *var;
 		int			attno;
 
+		/* we cannot also have a constraint name, per grammar */
+		Assert(!OidIsValid(onconflict->constraint));
+
 		if (!IsA(elem->expr, Var))
 		{
-			/* If not a plain Var, just shove it in inferElems for now */
+			/*
+			 * If not a plain Var, just shove it in inferElems for now.
+			 */
 			inferElems = lappend(inferElems, elem->expr);
 			continue;
 		}
@@ -867,45 +877,100 @@ infer_arbiter_indexes(PlannerInfo *root)
 	}
 
 	/*
-	 * Lookup named constraint's index.  This is not immediately returned
-	 * because some additional sanity checks are required.
+	 * Next, open all the indexes.  We need this list for two things: first,
+	 * if an ON CONSTRAINT clause was given, and that constraint's index is
+	 * undergoing REINDEX CONCURRENTLY, then we need to consider all matches
+	 * for that index.  Second, if an attribute list was specified in the ON
+	 * CONFLICT clause, we use the list to find the indexes whose attributes
+	 * match that list.
+	 */
+	indexList = RelationGetIndexList(relation);
+	foreach_oid(indexoid, indexList)
+	{
+		Relation	idxRel;
+
+		/*
+		 * Must open in this order to avoid deadlock.  Obtain the same lock
+		 * type that the executor will ultimately use.
+		 */
+		idxRel = index_open(indexoid, rte->rellockmode);
+		indexRelList = lappend(indexRelList, idxRel);
+	}
+
+	/*
+	 * If a constraint was named in the command, look up its index.  We don't
+	 * return it immediately because we need some additional sanity checks,
+	 * and also because we need to include other indexes as arbiters to
+	 * account for REINDEX CONCURRENTLY processing the constraint's index.
 	 */
 	if (onconflict->constraint != InvalidOid)
 	{
-		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
+		/* we cannot also have an explicit list of elements, per grammar */
+		Assert(onconflict->arbiterElems == NIL);
 
+		indexOidFromConstraint = get_constraint_index(onconflict->constraint);
 		if (indexOidFromConstraint == InvalidOid)
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 					 errmsg("constraint in ON CONFLICT clause has no associated index")));
+
+		/*
+		 * Find the named constraint index to extract its attributes and
+		 * predicates.
+		 */
+		foreach_ptr(RelationData, idxRel, indexRelList)
+		{
+			Form_pg_index idxForm = idxRel->rd_index;
+
+			if (idxForm->indisready)
+			{
+				if (indexOidFromConstraint == idxForm->indexrelid)
+				{
+					/*
+					 * Set up inferElems and inferPredExprs to match
+					 * the constraint index, so that we can match them
+					 * in the loop below.
+					 */
+					for (int natt = 0; natt < idxForm->indnkeyatts; natt++)
+					{
+						int			attno;
+
+						attno = idxRel->rd_index->indkey.values[natt];
+						if (attno != InvalidAttrNumber)
+							inferAttrs =
+								bms_add_member(inferAttrs,
+											   attno - FirstLowInvalidHeapAttributeNumber);
+					}
+
+					/* found it */
+					inferElems = RelationGetIndexExpressions(idxRel);
+					inferIndexExprs = RelationGetIndexPredicate(idxRel);
+					break;
+				}
+			}
+		}
 	}
 
 	/*
 	 * Using that representation, iterate through the list of indexes on the
 	 * target relation to try and find a match
 	 */
-	indexList = RelationGetIndexList(relation);
-
-	foreach(l, indexList)
+	foreach_ptr(RelationData, idxRel, indexRelList)
 	{
-		Oid			indexoid = lfirst_oid(l);
-		Relation	idxRel;
 		Form_pg_index idxForm;
 		Bitmapset  *indexedAttrs;
 		List	   *idxExprs;
 		List	   *predExprs;
 		AttrNumber	natt;
-		ListCell   *el;
+		bool		match;
 
 		/*
-		 * Extract info from the relation descriptor for the index.  Obtain
-		 * the same lock type that the executor will ultimately use.
+		 * Extract info from the relation descriptor for the index.
 		 *
 		 * Let executor complain about !indimmediate case directly, because
 		 * enforcement needs to occur there anyway when an inference clause is
 		 * omitted.
 		 */
-		idxRel = index_open(indexoid, rte->rellockmode);
 		idxForm = idxRel->rd_index;
 
 		/*
@@ -924,7 +989,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		 * indexes at least one index that is marked valid.
 		 */
 		if (!idxForm->indisready)
-			goto next;
+			continue;
 
 		/*
 		 * Note that we do not perform a check against indcheckxmin (like e.g.
@@ -934,7 +999,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		 */
 
 		/*
-		 * Look for match on "ON constraint_name" variant, which may not be
+		 * Look for match on "ON constraint_name" variant, which may not be a
 		 * unique constraint.  This can only be a constraint name.
 		 */
 		if (indexOidFromConstraint == idxForm->indexrelid)
@@ -944,31 +1009,37 @@ infer_arbiter_indexes(PlannerInfo *root)
 						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 						 errmsg("ON CONFLICT DO UPDATE not supported with exclusion constraints")));
 
+			/* Consider this one a match already */
 			results = lappend_oid(results, idxForm->indexrelid);
 			foundValid |= idxForm->indisvalid;
-			index_close(idxRel, NoLock);
-			break;
+			continue;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-			/* No point in further work for index in named constraint case */
-			goto next;
+			/*
+			 * In the case of "ON constraint_name DO UPDATE" we need to skip
+			 * non-unique candidates.
+			 */
+			if (!idxForm->indisunique && onconflict->action == ONCONFLICT_UPDATE)
+				continue;
+		}
+		else
+		{
+			/*
+			 * Only considering conventional inference at this point (not
+			 * named constraints), so index under consideration can be
+			 * immediately skipped if it's not unique.
+			 */
+			if (!idxForm->indisunique)
+				continue;
 		}
-
-		/*
-		 * Only considering conventional inference at this point (not named
-		 * constraints), so index under consideration can be immediately
-		 * skipped if it's not unique
-		 */
-		if (!idxForm->indisunique)
-			goto next;
 
 		/*
 		 * So-called unique constraints with WITHOUT OVERLAPS are really
 		 * exclusion constraints, so skip those too.
 		 */
 		if (idxForm->indisexclusion)
-			goto next;
+			continue;
 
 		/* Build BMS representation of plain (non expression) index attrs */
 		indexedAttrs = NULL;
@@ -983,17 +1054,20 @@ infer_arbiter_indexes(PlannerInfo *root)
 
 		/* Non-expression attributes (if any) must match */
 		if (!bms_equal(indexedAttrs, inferAttrs))
-			goto next;
+			continue;
 
 		/* Expression attributes (if any) must match */
 		idxExprs = RelationGetIndexExpressions(idxRel);
 		if (idxExprs && varno != 1)
 			ChangeVarNodes((Node *) idxExprs, 1, varno, 0);
 
-		foreach(el, onconflict->arbiterElems)
+		/*
+		 * If arbiterElems are present, check them.  (Note that if a
+		 * constraint name was given in the command line, this list is NIL.)
+		 */
+		match = true;
+		foreach_ptr(InferenceElem, elem, onconflict->arbiterElems)
 		{
-			InferenceElem *elem = (InferenceElem *) lfirst(el);
-
 			/*
 			 * Ensure that collation/opclass aspects of inference expression
 			 * element match.  Even though this loop is primarily concerned
@@ -1002,7 +1076,10 @@ infer_arbiter_indexes(PlannerInfo *root)
 			 * attributes appearing as inference elements.
 			 */
 			if (!infer_collation_opclass_match(elem, idxRel, idxExprs))
-				goto next;
+			{
+				match = false;
+				break;
+			}
 
 			/*
 			 * Plain Vars don't factor into count of expression elements, and
@@ -1023,37 +1100,58 @@ infer_arbiter_indexes(PlannerInfo *root)
 				list_member(idxExprs, elem->expr))
 				continue;
 
-			goto next;
+			match = false;
+			break;
 		}
+		if (!match)
+			continue;
 
 		/*
-		 * Now that all inference elements were matched, ensure that the
+		 * In case of inference from an attribute list, ensure that the
 		 * expression elements from inference clause are not missing any
 		 * cataloged expressions.  This does the right thing when unique
 		 * indexes redundantly repeat the same attribute, or if attributes
 		 * redundantly appear multiple times within an inference clause.
+		 *
+		 * In case a constraint was named, ensure the candidate has an equal
+		 * set of expressions as the named constraint's index.
 		 */
 		if (list_difference(idxExprs, inferElems) != NIL)
-			goto next;
+			continue;
 
-		/*
-		 * If it's a partial index, its predicate must be implied by the ON
-		 * CONFLICT's WHERE clause.
-		 */
 		predExprs = RelationGetIndexPredicate(idxRel);
 		if (predExprs && varno != 1)
 			ChangeVarNodes((Node *) predExprs, 1, varno, 0);
 
-		if (!predicate_implied_by(predExprs, (List *) onconflict->arbiterWhere, false))
-			goto next;
+		/*
+		 * If it's a partial index and conventional inference, its predicate
+		 * must be implied by the ON CONFLICT's WHERE clause.
+		 */
+		if (indexOidFromConstraint == InvalidOid &&
+			!predicate_implied_by(predExprs, inferIndexExprs, false))
+			continue;
 
+		/*
+		 * If it's a partial index and named constraint predicates must be
+		 * equal.
+		 */
+		if (indexOidFromConstraint != InvalidOid &&
+			list_difference(predExprs, inferIndexExprs) != NIL)
+			continue;
+
+		/* Consider this a match */
 		results = lappend_oid(results, idxForm->indexrelid);
 		foundValid |= idxForm->indisvalid;
-next:
+	}
+
+	/* Close all indexes */
+	foreach_ptr(RelationData, idxRel, indexRelList)
+	{
 		index_close(idxRel, NoLock);
 	}
 
 	list_free(indexList);
+	list_free(indexRelList);
 	table_close(relation, NoLock);
 
 	/* We require at least one indisvalid index */
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
index ca26f6f61f2..bee9860c513 100644
--- a/src/backend/parser/parse_clause.c
+++ b/src/backend/parser/parse_clause.c
@@ -3277,11 +3277,11 @@ resolve_unique_index_expr(ParseState *pstate, InferClause *infer,
 		 * Raw grammar re-uses CREATE INDEX infrastructure for unique index
 		 * inference clause, and so will accept opclasses by name and so on.
 		 *
-		 * Make no attempt to match ASC or DESC ordering or NULLS FIRST/NULLS
-		 * LAST ordering, since those are not significant for inference
-		 * purposes (any unique index matching the inference specification in
-		 * other regards is accepted indifferently).  Actively reject this as
-		 * wrong-headed.
+		 * Make no attempt to match ASC or DESC ordering, NULLS FIRST/NULLS
+		 * LAST ordering or opclass options, since those are not significant
+		 * for inference purposes (any unique index matching the inference
+		 * specification in other regards is accepted indifferently). Actively
+		 * reject this as wrong-headed.
 		 */
 		if (ielem->ordering != SORTBY_DEFAULT)
 			ereport(ERROR,
@@ -3295,6 +3295,12 @@ resolve_unique_index_expr(ParseState *pstate, InferClause *infer,
 					 errmsg("NULLS FIRST/LAST is not allowed in ON CONFLICT clause"),
 					 parser_errposition(pstate,
 										exprLocation((Node *) infer))));
+		if (ielem->opclassopts)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+					errmsg("operator class options are not allowed in ON CONFLICT clause"),
+					parser_errposition(pstate,
+									   exprLocation((Node *) infer)));
 
 		if (!ielem->expr)
 		{
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 7b3c0c4b716..0a9716db27c 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -19,6 +19,7 @@ ISOLATION = basic \
 	    syscache-update-pruned \
 	    index-concurrently-upsert \
 	    reindex-concurrently-upsert \
+	    reindex-concurrently-upsert-on-constraint \
 	    index-concurrently-upsert-predicate
 
 TAP_TESTS = 1
diff --git a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out b/src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out
new file mode 100644
index 00000000000..c1ac1f77c61
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out
@@ -0,0 +1,238 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: 
+	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+ <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: 
+	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+ <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: 
+	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+ <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 485b483e3ca..0706cd3d6e9 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -51,6 +51,7 @@ tests += {
       'index-concurrently-upsert',
       'reindex-concurrently-upsert',
       'index-concurrently-upsert-predicate',
+      'reindex-concurrently-upsert-on-constraint',
     ],
     'runningcheck': false, # see syscache-update-pruned
     # Some tests wait for all snapshots, so avoid parallel execution
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec
new file mode 100644
index 00000000000..8126256460c
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec
@@ -0,0 +1,110 @@
+# Test race conditions involving:
+#
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: concurrently REINDEX the primary key
+#
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+	ALTER TABLE test.tbl SET (parallel_workers=0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup
+{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+}
+step s1_start_upsert
+{
+	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+}
+
+session s2
+setup
+{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+}
+step s2_start_upsert
+{
+	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+}
+
+session s3
+setup
+{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead
+{
+	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+}
+step s3_setup_wait_before_swap
+{
+	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+}
+step s3_start_reindex
+{
+	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+}
+
+session s4
+step s4_wakeup_to_swap
+{
+	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
+}
+step s4_wakeup_s1
+{
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+}
+step s4_wakeup_s2
+{
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+}
+step s4_wakeup_to_set_dead
+{
+	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
-- 
2.47.3

From 13735733ad82bd7e3963140e6856e458d8eb7156 Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Sun, 30 Nov 2025 16:49:20 +0100
Subject: [PATCH v15 2/2] Revert "Doc: cover index CONCURRENTLY causing errors
 in INSERT ... ON CONFLICT."

This reverts commit 8b18ed6dfbb8b3e4483801b513fea6b429140569.
---
 doc/src/sgml/ref/insert.sgml         | 9 ---------
 src/backend/optimizer/util/plancat.c | 5 -----
 2 files changed, 14 deletions(-)

diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 0598b8dea34..04962e39e12 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -594,15 +594,6 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
     </para>
    </tip>
 
-   <warning>
-    <para>
-      While <command>CREATE INDEX CONCURRENTLY</command> or <command>REINDEX
-      CONCURRENTLY</command> is running on a unique index, <command>INSERT
-      ... ON CONFLICT</command> statements on the same table may unexpectedly
-      fail with a unique violation.
-    </para>
-   </warning>
-
   </refsect2>
  </refsect1>
 
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 7af9a2064e3..d5325f0f732 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -789,11 +789,6 @@ find_relation_notnullatts(PlannerInfo *root, Oid relid)
  * the purposes of inference.  If no opclass (or collation) is specified, then
  * all matching indexes (that may or may not match the default in terms of
  * each attribute opclass/collation) are used for inference.
- *
- * Note: during index CONCURRENTLY operations, different transactions may
- * reference different sets of arbiter indexes. This can lead to false unique
- * constraint violations that wouldn't occur during normal operations.  For
- * more information, see insert.sgml.
  */
 List *
 infer_arbiter_indexes(PlannerInfo *root)
-- 
2.43.0

From 53e41c5bdd89dbaf5022f59169d0de483f82babc Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Sun, 30 Nov 2025 16:48:55 +0100
Subject: [PATCH v15 1/2] Modify the ExecInitPartitionInfo function to consider
  partitioned indexes that are potentially processed by REINDEX CONCURRENTLY
 as  arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.
---
 src/backend/executor/execPartition.c          | 127 +++++++++-
 src/test/modules/injection_points/Makefile    |   3 +-
 ...eindex-concurrently-upsert-partitioned.out | 232 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   1 +
 ...index-concurrently-upsert-partitioned.spec |  96 ++++++++
 5 files changed, 446 insertions(+), 13 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 0dcce181f09..bd3527393ec 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -15,6 +15,7 @@
 
 #include "access/table.h"
 #include "access/tableam.h"
+#include "catalog/index.h"
 #include "catalog/partition.h"
 #include "executor/execPartition.h"
 #include "executor/executor.h"
@@ -490,6 +491,62 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Only indexes of the same relation are supported.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int	i;
+
+	Assert(arbiterIndexRelation->rd_index->indrelid == indexRelation->rd_index->indrelid);
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+
+	if (arbiterIndexInfo->ii_NullsNotDistinct != indexInfo->ii_NullsNotDistinct)
+		return false;
+
+	/* and same number of key attributes */
+	if (arbiterIndexInfo->ii_NumIndexKeyAttrs != indexInfo->ii_NumIndexKeyAttrs)
+		return false;
+
+	/* No support currently for comparing exclusion indexes. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+
+	for (i = 0; i < arbiterIndexInfo->ii_NumIndexKeyAttrs; i++)
+	{
+		if (arbiterIndexRelation->rd_indcollation[i] != indexRelation->rd_indcollation[i])
+			return false;
+
+		if (arbiterIndexRelation->rd_opfamily[i] != indexRelation->rd_opfamily[i])
+			return false;
+
+		if (arbiterIndexRelation->rd_index->indkey.values[i] != indexRelation->rd_index->indkey.values[i])
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -690,7 +747,9 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		TupleDesc	partrelDesc = RelationGetDescr(partrel);
 		ExprContext *econtext = mtstate->ps.ps_ExprContext;
 		ListCell   *lc;
-		List	   *arbiterIndexes = NIL;
+		List	   *arbiterIndexes = NIL,
+				   *arbiterIndexesOffset = NIL;
+		int		   additional_arbiters = 0;
 
 		/*
 		 * If there is a list of arbiter indexes, map it to a list of indexes
@@ -698,36 +757,80 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		 * list and searching for ancestry relationships to each index in the
 		 * ancestor table.
 		 */
-		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
-		{
-			List	   *childIdxs;
+		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL) {
+			List	   *childIdxs,
+					   *nonAncestorIdxOffset = NIL;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
 			foreach(lc, childIdxs)
 			{
 				Oid			childIdx = lfirst_oid(lc);
+				int			i = foreach_current_index(lc);
 				List	   *ancestors;
-				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach_oid(oid, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, oid))
+						{
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+							arbiterIndexesOffset = lappend_int(arbiterIndexesOffset, i);
+						}
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxOffset = lappend_int(nonAncestorIdxOffset, i);
+
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxOffset && arbiterIndexesOffset)
+			{
+				foreach_int(childIdxOffset, nonAncestorIdxOffset)
+				{
+					Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[childIdxOffset];
+					IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[childIdxOffset];
+					Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+					/* It is too early to use non-ready indexes as arbiters */
+					if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+						continue;
+
+					foreach_int(arbiterIdxOffset, arbiterIndexesOffset)
+					{
+						Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[arbiterIdxOffset];
+						IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[arbiterIdxOffset];
+
+						/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+						if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+													   nonAncestorIndexRelation, nonAncestorIndexInfo))
+						{
+							arbiterIndexes = lappend_oid(arbiterIndexes,
+														 nonAncestorIndexRelation->rd_index->indexrelid);
+							additional_arbiters++;
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxOffset);
 		}
 
 		/*
 		 * If the resulting lists are of inequal length, something is wrong.
-		 * XXX This may happen because we don't match the lists correctly when
-		 * a partitioned index is being processed by REINDEX CONCURRENTLY.
-		 * FIXME later.
+		 * But we need to consider additional arbiter indexes also.
 		 */
 		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
+			list_length(arbiterIndexes) - additional_arbiters)
 			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 7b3c0c4b716..e10475d2665 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -19,7 +19,8 @@ ISOLATION = basic \
 	    syscache-update-pruned \
 	    index-concurrently-upsert \
 	    reindex-concurrently-upsert \
-	    index-concurrently-upsert-predicate
+	    index-concurrently-upsert-predicate \
+	    reindex-concurrently-upsert-partitioned
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out b/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
new file mode 100644
index 00000000000..588ffbd57a5
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 485b483e3ca..3e06220fe31 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -51,6 +51,7 @@ tests += {
       'index-concurrently-upsert',
       'reindex-concurrently-upsert',
       'index-concurrently-upsert-predicate',
+      'reindex-concurrently-upsert-partitioned'
     ],
     'runningcheck': false, # see syscache-update-pruned
     # Some tests wait for all snapshots, so avoid parallel execution
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
new file mode 100644
index 00000000000..c8a8eb9cca5
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
@@ -0,0 +1,96 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 7b3c0c4b716..46566937d81 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -11,10 +11,10 @@ EXTENSION = injection_points
 DATA = injection_points--1.0.sql
 PGFILEDESC = "injection_points - facility for injection points"
 
-REGRESS = injection_points hashagg reindex_conc vacuum
+XREGRESS = injection_points hashagg reindex_conc vacuum
 REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
-ISOLATION = basic \
+XISOLATION = basic \
 	    inplace \
 	    syscache-update-pruned \
 	    index-concurrently-upsert \
@@ -28,6 +28,9 @@ NO_INSTALLCHECK = 1
 
 export enable_injection_points
 
+REGRESS_SHLIB=$(abs_top_builddir)/src/test/regress/regress$(DLSUFFIX)
+export REGRESS_SHLIB
+
 ifdef USE_PGXS
 PG_CONFIG = pg_config
 PGXS := $(shell $(PG_CONFIG) --pgxs)
diff --git a/src/test/modules/injection_points/isolation_schedule b/src/test/modules/injection_points/isolation_schedule
new file mode 100644
index 00000000000..9b71d065309
--- /dev/null
+++ b/src/test/modules/injection_points/isolation_schedule
@@ -0,0 +1,23 @@
+test: basic
+test: inplace
+test: syscache-update-pruned
+test: index-concurrently-upsert
+test: index-concurrently-upsert
+test: index-concurrently-upsert
+test: index-concurrently-upsert
+test: index-concurrently-upsert
+test: index-concurrently-upsert
+test: index-concurrently-upsert
+test: index-concurrently-upsert
+test: index-concurrently-upsert
+test: index-concurrently-upsert
+test: reindex-concurrently-upsert
+test: reindex-concurrently-upsert
+test: reindex-concurrently-upsert
+test: reindex-concurrently-upsert
+test: reindex-concurrently-upsert
+test: reindex-concurrently-upsert
+test: reindex-concurrently-upsert
+test: reindex-concurrently-upsert
+test: reindex-concurrently-upsert
+test: reindex-concurrently-upsert
diff --git a/src/test/modules/injection_points/t/099_isolation_regress.pl b/src/test/modules/injection_points/t/099_isolation_regress.pl
new file mode 100644
index 00000000000..047530c3d6a
--- /dev/null
+++ b/src/test/modules/injection_points/t/099_isolation_regress.pl
@@ -0,0 +1,55 @@
+
+# Copyright (c) 2024, PostgreSQL Global Development Group
+
+# Run the standard regression tests with streaming replication
+use strict;
+use warnings FATAL => 'all';
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Test::More;
+use File::Basename;
+
+# Initialize primary node
+my $node_primary = PostgreSQL::Test::Cluster->new('primary');
+$node_primary->init();
+
+# Increase some settings that Cluster->new makes too low by default.
+$node_primary->adjust_conf('postgresql.conf', 'max_connections', '25');
+$node_primary->append_conf('postgresql.conf',
+	'max_prepared_transactions = 10');
+
+$node_primary->start;
+
+my $dlpath = dirname($ENV{REGRESS_SHLIB});
+my $outputdir = $PostgreSQL::Test::Utils::tmp_check;
+
+# Run the regression tests against the primary.
+my $extra_opts = $ENV{EXTRA_REGRESS_OPTS} || "";
+
+my $rc =
+  system( ($ENV{PG_REGRESS} =~ s/regress\/pg_regress/isolation\/pg_isolation_regress/r)
+	  . " $extra_opts "
+	  . "--dlpath=\"$dlpath\" "
+	  . "--bindir= "
+	  . "--host="
+	  . $node_primary->host . " "
+	  . "--port="
+	  . $node_primary->port . " "
+	  . "--schedule=./isolation_schedule "
+	  . "--inputdir=./ "
+	  . "--outputdir=\"$outputdir\"");
+if ($rc != 0)
+{
+	# Dump out the regression diffs file, if there is one
+	my $diffs = "$outputdir/regression.diffs";
+	if (-e $diffs)
+	{
+		print "=== dumping $diffs ===\n";
+		print slurp_file($diffs);
+		print "=== EOF ===\n";
+	}
+}
+is($rc, 0, 'regression tests pass');
+
+
+done_testing();

From 5dc3e4eb50e445a291a13663fc9ce93d0db96b1c Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Sun, 30 Nov 2025 16:49:20 +0100
Subject: [PATCH v16 2/3] Revert "Doc: cover index CONCURRENTLY causing errors
 in INSERT ... ON CONFLICT."

This reverts commit 8b18ed6dfbb8b3e4483801b513fea6b429140569.
---
 doc/src/sgml/ref/insert.sgml         | 9 ---------
 src/backend/optimizer/util/plancat.c | 5 -----
 2 files changed, 14 deletions(-)

diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 0598b8dea34..04962e39e12 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -594,15 +594,6 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
     </para>
    </tip>
 
-   <warning>
-    <para>
-      While <command>CREATE INDEX CONCURRENTLY</command> or <command>REINDEX
-      CONCURRENTLY</command> is running on a unique index, <command>INSERT
-      ... ON CONFLICT</command> statements on the same table may unexpectedly
-      fail with a unique violation.
-    </para>
-   </warning>
-
   </refsect2>
  </refsect1>
 
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 7af9a2064e3..d5325f0f732 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -789,11 +789,6 @@ find_relation_notnullatts(PlannerInfo *root, Oid relid)
  * the purposes of inference.  If no opclass (or collation) is specified, then
  * all matching indexes (that may or may not match the default in terms of
  * each attribute opclass/collation) are used for inference.
- *
- * Note: during index CONCURRENTLY operations, different transactions may
- * reference different sets of arbiter indexes. This can lead to false unique
- * constraint violations that wouldn't occur during normal operations.  For
- * more information, see insert.sgml.
  */
 List *
 infer_arbiter_indexes(PlannerInfo *root)
-- 
2.43.0

From a09dcb5f2a0fb5801f205d4f5e0448ddbe064d38 Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Mon, 1 Dec 2025 12:14:13 +0100
Subject: [PATCH v16 3/3] Refactor test to avoid any additional injection
 points and notice.

---
 src/backend/utils/time/snapmgr.c              |   1 -
 .../index-concurrently-upsert-predicate.out   |   8 +-
 .../index-concurrently-upsert-predicate_1.out | 116 ------------------
 .../expected/index-concurrently-upsert.out    |  14 +--
 .../expected/index-concurrently-upsert_1.out  | 116 ------------------
 .../index-concurrently-upsert-predicate.spec  |  31 ++++-
 .../specs/index-concurrently-upsert.spec      |  36 +++++-
 7 files changed, 64 insertions(+), 258 deletions(-)
 delete mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
 delete mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert_1.out

diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 434abbf6b6f..24f73a49d27 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -459,7 +459,6 @@ InvalidateCatalogSnapshot(void)
 		pairingheap_remove(&RegisteredSnapshots, &CatalogSnapshot->ph_node);
 		CatalogSnapshot = NULL;
 		SnapshotResetXmin();
-		INJECTION_POINT("pre-invalidate-catalog-snapshot-end", NULL);
 		INJECTION_POINT("invalidate-catalog-snapshot-end", NULL);
 	}
 }
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
index 5a57cd5fa40..11b23e8721f 100644
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
+++ b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
@@ -1,6 +1,6 @@
 Parsed test spec with 5 sessions
 
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
 injection_points_attach
 -----------------------
                        
@@ -37,16 +37,12 @@ case
     
 (1 row)
 
-step s5_noop: 
- <waiting ...>
 step s3_start_create_index: 
 	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
  <waiting ...>
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
 step s1_start_upsert: 
 	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
  <waiting ...>
-step s5_noop: <... completed>
 step s4_wakeup_define_index_before_set_valid: 
 	SELECT injection_points_detach('define-index-before-set-valid');
 	SELECT injection_points_wakeup('define-index-before-set-valid');
@@ -65,6 +61,7 @@ step s2_start_upsert:
 	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
  <waiting ...>
 step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
+	CALL test.wait_for_injection_point();
 	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
 	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
 
@@ -106,7 +103,6 @@ injection_points_wakeup
                        
 (1 row)
 
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
 step s1_start_upsert: <... completed>
 step s2_start_upsert: <... completed>
 step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
deleted file mode 100644
index d453dd62617..00000000000
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
+++ /dev/null
@@ -1,116 +0,0 @@
-Parsed test spec with 5 sessions
-
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
-step s1_attach_invalidate_catalog_snapshot: 
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
- <waiting ...>
-step s4_wakeup_s1_setup: 
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-			      WHERE wait_event_type = 'InjectionPoint' AND
-			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-
-case
-----
-    
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: <... completed>
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s5_noop: 
- <waiting ...>
-step s3_start_create_index: 
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
- <waiting ...>
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_noop: <... completed>
-step s4_wakeup_define_index_before_set_valid: 
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert.out b/src/test/modules/injection_points/expected/index-concurrently-upsert.out
index 97386a35bed..7bcf8d34053 100644
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert.out
+++ b/src/test/modules/injection_points/expected/index-concurrently-upsert.out
@@ -1,6 +1,6 @@
 Parsed test spec with 5 sessions
 
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
 injection_points_attach
 -----------------------
                        
@@ -27,8 +27,8 @@ injection_points_attach
 step s4_wakeup_s1_setup: 
 	SELECT CASE WHEN
 			(SELECT pid FROM pg_stat_activity
-			      WHERE wait_event_type = 'InjectionPoint' AND
-			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
+				  WHERE wait_event_type = 'InjectionPoint' AND
+				  wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
 			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
 		END;
 
@@ -37,16 +37,12 @@ case
     
 (1 row)
 
-step s5_noop: 
- <waiting ...>
 step s3_start_create_index: 
 	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
  <waiting ...>
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
 step s1_start_upsert: 
-    INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
  <waiting ...>
-step s5_noop: <... completed>
 step s4_wakeup_define_index_before_set_valid: 
 	SELECT injection_points_detach('define-index-before-set-valid');
 	SELECT injection_points_wakeup('define-index-before-set-valid');
@@ -65,6 +61,7 @@ step s2_start_upsert:
 	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
  <waiting ...>
 step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
+	CALL test.wait_for_injection_point();
 	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
 	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
 
@@ -106,7 +103,6 @@ injection_points_wakeup
                        
 (1 row)
 
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
 step s1_start_upsert: <... completed>
 step s2_start_upsert: <... completed>
 step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out b/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
deleted file mode 100644
index 4bd51b2b511..00000000000
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
+++ /dev/null
@@ -1,116 +0,0 @@
-Parsed test spec with 5 sessions
-
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s5_noop s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
-step s1_attach_invalidate_catalog_snapshot: 
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
- <waiting ...>
-step s4_wakeup_s1_setup: 
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-			      WHERE wait_event_type = 'InjectionPoint' AND
-			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-
-case
-----
-    
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: <... completed>
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s5_noop: 
- <waiting ...>
-step s3_start_create_index: 
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
- <waiting ...>
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
-step s1_start_upsert: 
-    INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_noop: <... completed>
-step s4_wakeup_define_index_before_set_valid: 
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-s1: NOTICE:  notice triggered for injection point pre-invalidate-catalog-snapshot-end
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec b/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
index 1cbcaa6963f..34016b93bb0 100644
--- a/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
+++ b/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
@@ -27,7 +27,6 @@ setup
 {
 	SELECT injection_points_set_local();
 	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-	SELECT injection_points_attach('pre-invalidate-catalog-snapshot-end', 'notice');
 }
 step s1_attach_invalidate_catalog_snapshot
 {
@@ -91,19 +90,43 @@ step s4_wakeup_define_index_before_set_valid
 }
 
 session s5
-step s5_noop
-{
+setup {
+	CREATE OR REPLACE PROCEDURE test.wait_for_injection_point()
+	LANGUAGE plpgsql
+	AS $$
+	DECLARE
+		v_waiting_pid INTEGER;
+	BEGIN
+		SELECT pid INTO v_waiting_pid
+		FROM pg_stat_activity
+		WHERE wait_event_type = 'InjectionPoint'
+		  AND wait_event = 'invalidate-catalog-snapshot-end'
+		LIMIT 1;
+
+		IF v_waiting_pid IS NOT NULL THEN
+			RETURN;
+		END IF;
+
+		PERFORM pg_sleep(100);
+
+		CALL test.wait_for_injection_point();
+	END;
+	$$;
 }
 step s5_wakeup_s1_from_invalidate_catalog_snapshot
 {
+	CALL test.wait_for_injection_point();
 	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
 	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
 }
+teardown
+{
+  DROP PROCEDURE test.wait_for_injection_point;
+}
 
 permutation
 	s1_attach_invalidate_catalog_snapshot
 	s4_wakeup_s1_setup
-	s5_noop(s1_start_upsert notices 1)
 	s3_start_create_index(s1_start_upsert, s2_start_upsert)
 	s1_start_upsert
 	s4_wakeup_define_index_before_set_valid
diff --git a/src/test/modules/injection_points/specs/index-concurrently-upsert.spec b/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
index 2a6d888dcea..92fc0933e91 100644
--- a/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
+++ b/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
@@ -26,7 +26,6 @@ setup
 {
 	SELECT injection_points_set_local();
 	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-	SELECT injection_points_attach('pre-invalidate-catalog-snapshot-end', 'notice');
 }
 step s1_attach_invalidate_catalog_snapshot
 {
@@ -34,7 +33,7 @@ step s1_attach_invalidate_catalog_snapshot
 }
 step s1_start_upsert
 {
-    INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
 }
 
 session s2
@@ -68,8 +67,8 @@ step s4_wakeup_s1_setup
 {
 	SELECT CASE WHEN
 			(SELECT pid FROM pg_stat_activity
-			      WHERE wait_event_type = 'InjectionPoint' AND
-			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
+				  WHERE wait_event_type = 'InjectionPoint' AND
+				  wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
 			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
 		END;
 }
@@ -90,19 +89,44 @@ step s4_wakeup_define_index_before_set_valid
 }
 
 session s5
-step s5_noop
+setup
 {
+	CREATE OR REPLACE PROCEDURE test.wait_for_injection_point()
+	LANGUAGE plpgsql
+	AS $$
+	DECLARE
+		v_waiting_pid INTEGER;
+	BEGIN
+		SELECT pid INTO v_waiting_pid
+		FROM pg_stat_activity
+		WHERE wait_event_type = 'InjectionPoint'
+		  AND wait_event = 'invalidate-catalog-snapshot-end'
+		LIMIT 1;
+
+		IF v_waiting_pid IS NOT NULL THEN
+			RETURN;
+		END IF;
+
+		PERFORM pg_sleep(100);
+
+		CALL test.wait_for_injection_point();
+	END;
+	$$;
 }
 step s5_wakeup_s1_from_invalidate_catalog_snapshot
 {
+	CALL test.wait_for_injection_point();
 	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
 	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
 }
+teardown
+{
+  DROP PROCEDURE test.wait_for_injection_point;
+}
 
 permutation
 	s1_attach_invalidate_catalog_snapshot
 	s4_wakeup_s1_setup
-	s5_noop(s1_start_upsert notices 1)
 	s3_start_create_index(s1_start_upsert, s2_start_upsert)
 	s1_start_upsert
 	s4_wakeup_define_index_before_set_valid
-- 
2.43.0

From af5e27d4150dd53d313122c02da7ce4d3c07f332 Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Sun, 30 Nov 2025 16:48:55 +0100
Subject: [PATCH v16 1/3] Modify the ExecInitPartitionInfo function to consider
  partitioned indexes that are potentially processed by REINDEX CONCURRENTLY
 as  arbiters as well.

This is necessary to ensure that all concurrent transactions use the same set of arbiter indexes.
---
 src/backend/executor/execPartition.c          | 127 +++++++++-
 src/test/modules/injection_points/Makefile    |   3 +-
 ...eindex-concurrently-upsert-partitioned.out | 232 ++++++++++++++++++
 src/test/modules/injection_points/meson.build |   1 +
 ...index-concurrently-upsert-partitioned.spec |  96 ++++++++
 5 files changed, 446 insertions(+), 13 deletions(-)
 create mode 100644 src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
 create mode 100644 src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 0dcce181f09..bd3527393ec 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -15,6 +15,7 @@
 
 #include "access/table.h"
 #include "access/tableam.h"
+#include "catalog/index.h"
 #include "catalog/partition.h"
 #include "executor/execPartition.h"
 #include "executor/executor.h"
@@ -490,6 +491,62 @@ ExecFindPartition(ModifyTableState *mtstate,
 	return rri;
 }
 
+/*
+ * IsIndexCompatibleAsArbiter
+ * 		Checks if the indexes are identical in terms of being used
+ * 		as arbiters for the INSERT ON CONFLICT operation by comparing
+ * 		them to the provided arbiter index.
+ *
+ * Only indexes of the same relation are supported.
+ *
+ * Returns the true if indexes are compatible.
+ */
+static bool
+IsIndexCompatibleAsArbiter(Relation	arbiterIndexRelation,
+						   IndexInfo  *arbiterIndexInfo,
+						   Relation	indexRelation,
+						   IndexInfo  *indexInfo)
+{
+	int	i;
+
+	Assert(arbiterIndexRelation->rd_index->indrelid == indexRelation->rd_index->indrelid);
+
+	if (arbiterIndexInfo->ii_Unique != indexInfo->ii_Unique)
+		return false;
+
+	if (arbiterIndexInfo->ii_NullsNotDistinct != indexInfo->ii_NullsNotDistinct)
+		return false;
+
+	/* and same number of key attributes */
+	if (arbiterIndexInfo->ii_NumIndexKeyAttrs != indexInfo->ii_NumIndexKeyAttrs)
+		return false;
+
+	/* No support currently for comparing exclusion indexes. */
+	if (arbiterIndexInfo->ii_ExclusionOps != NULL || indexInfo->ii_ExclusionOps != NULL)
+		return false;
+
+	for (i = 0; i < arbiterIndexInfo->ii_NumIndexKeyAttrs; i++)
+	{
+		if (arbiterIndexRelation->rd_indcollation[i] != indexRelation->rd_indcollation[i])
+			return false;
+
+		if (arbiterIndexRelation->rd_opfamily[i] != indexRelation->rd_opfamily[i])
+			return false;
+
+		if (arbiterIndexRelation->rd_index->indkey.values[i] != indexRelation->rd_index->indkey.values[i])
+			return false;
+	}
+
+	if (list_difference(RelationGetIndexExpressions(arbiterIndexRelation),
+						RelationGetIndexExpressions(indexRelation)) != NIL)
+		return false;
+
+	if (list_difference(RelationGetIndexPredicate(arbiterIndexRelation),
+						RelationGetIndexPredicate(indexRelation)) != NIL)
+		return false;
+	return true;
+}
+
 /*
  * ExecInitPartitionInfo
  *		Lock the partition and initialize ResultRelInfo.  Also setup other
@@ -690,7 +747,9 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		TupleDesc	partrelDesc = RelationGetDescr(partrel);
 		ExprContext *econtext = mtstate->ps.ps_ExprContext;
 		ListCell   *lc;
-		List	   *arbiterIndexes = NIL;
+		List	   *arbiterIndexes = NIL,
+				   *arbiterIndexesOffset = NIL;
+		int		   additional_arbiters = 0;
 
 		/*
 		 * If there is a list of arbiter indexes, map it to a list of indexes
@@ -698,36 +757,80 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 		 * list and searching for ancestry relationships to each index in the
 		 * ancestor table.
 		 */
-		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL)
-		{
-			List	   *childIdxs;
+		if (rootResultRelInfo->ri_onConflictArbiterIndexes != NIL) {
+			List	   *childIdxs,
+					   *nonAncestorIdxOffset = NIL;
 
 			childIdxs = RelationGetIndexList(leaf_part_rri->ri_RelationDesc);
 
 			foreach(lc, childIdxs)
 			{
 				Oid			childIdx = lfirst_oid(lc);
+				int			i = foreach_current_index(lc);
 				List	   *ancestors;
-				ListCell   *lc2;
 
 				ancestors = get_partition_ancestors(childIdx);
-				foreach(lc2, rootResultRelInfo->ri_onConflictArbiterIndexes)
+				if (ancestors)
 				{
-					if (list_member_oid(ancestors, lfirst_oid(lc2)))
-						arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+					foreach_oid(oid, rootResultRelInfo->ri_onConflictArbiterIndexes)
+					{
+						if (list_member_oid(ancestors, oid))
+						{
+							arbiterIndexes = lappend_oid(arbiterIndexes, childIdx);
+							arbiterIndexesOffset = lappend_int(arbiterIndexesOffset, i);
+						}
+					}
 				}
+				else /* No ancestor was found for that index. Save it for rechecking later. */
+					nonAncestorIdxOffset = lappend_int(nonAncestorIdxOffset, i);
+
 				list_free(ancestors);
 			}
+
+			/*
+			 * If any non-ancestor indexes are found, we need to compare them with other
+			 * indexes of the relation that will be used as arbiters. This is necessary
+			 * when a partitioned index is processed by REINDEX CONCURRENTLY. Both indexes
+			 * must be considered as arbiters to ensure that all concurrent transactions
+			 * use the same set of arbiters.
+			 */
+			if (nonAncestorIdxOffset && arbiterIndexesOffset)
+			{
+				foreach_int(childIdxOffset, nonAncestorIdxOffset)
+				{
+					Relation nonAncestorIndexRelation = leaf_part_rri->ri_IndexRelationDescs[childIdxOffset];
+					IndexInfo *nonAncestorIndexInfo = leaf_part_rri->ri_IndexRelationInfo[childIdxOffset];
+					Assert(!list_member_oid(arbiterIndexes, nonAncestorIndexRelation->rd_index->indexrelid));
+
+					/* It is too early to use non-ready indexes as arbiters */
+					if (!nonAncestorIndexInfo->ii_ReadyForInserts)
+						continue;
+
+					foreach_int(arbiterIdxOffset, arbiterIndexesOffset)
+					{
+						Relation arbiterIndexRelation = leaf_part_rri->ri_IndexRelationDescs[arbiterIdxOffset];
+						IndexInfo *arbiterIndexInfo = leaf_part_rri->ri_IndexRelationInfo[arbiterIdxOffset];
+
+						/* If non-ancestor index are compatible to arbiter - use it as arbiter too. */
+						if (IsIndexCompatibleAsArbiter(arbiterIndexRelation, arbiterIndexInfo,
+													   nonAncestorIndexRelation, nonAncestorIndexInfo))
+						{
+							arbiterIndexes = lappend_oid(arbiterIndexes,
+														 nonAncestorIndexRelation->rd_index->indexrelid);
+							additional_arbiters++;
+						}
+					}
+				}
+			}
+			list_free(nonAncestorIdxOffset);
 		}
 
 		/*
 		 * If the resulting lists are of inequal length, something is wrong.
-		 * XXX This may happen because we don't match the lists correctly when
-		 * a partitioned index is being processed by REINDEX CONCURRENTLY.
-		 * FIXME later.
+		 * But we need to consider additional arbiter indexes also.
 		 */
 		if (list_length(rootResultRelInfo->ri_onConflictArbiterIndexes) !=
-			list_length(arbiterIndexes))
+			list_length(arbiterIndexes) - additional_arbiters)
 			elog(ERROR, "invalid arbiter index list");
 		leaf_part_rri->ri_onConflictArbiterIndexes = arbiterIndexes;
 
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index 7b3c0c4b716..e10475d2665 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -19,7 +19,8 @@ ISOLATION = basic \
 	    syscache-update-pruned \
 	    index-concurrently-upsert \
 	    reindex-concurrently-upsert \
-	    index-concurrently-upsert-predicate
+	    index-concurrently-upsert-predicate \
+	    reindex-concurrently-upsert-partitioned
 
 TAP_TESTS = 1
 
diff --git a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out b/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
new file mode 100644
index 00000000000..588ffbd57a5
--- /dev/null
+++ b/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
@@ -0,0 +1,232 @@
+Parsed test spec with 4 sessions
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_swap: 
+	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_to_swap: 
+	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
+
+starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_set_local
+--------------------------
+                          
+(1 row)
+
+step s3_setup_wait_before_set_dead: 
+	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_reindex: REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+ <waiting ...>
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s4_wakeup_to_set_dead: 
+	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: <... completed>
+step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 485b483e3ca..3e06220fe31 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -51,6 +51,7 @@ tests += {
       'index-concurrently-upsert',
       'reindex-concurrently-upsert',
       'index-concurrently-upsert-predicate',
+      'reindex-concurrently-upsert-partitioned'
     ],
     'runningcheck': false, # see syscache-update-pruned
     # Some tests wait for all snapshots, so avoid parallel execution
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
new file mode 100644
index 00000000000..c8a8eb9cca5
--- /dev/null
+++ b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
@@ -0,0 +1,96 @@
+# Test race conditions involving:
+# - s1: UPSERT a tuple
+# - s2: UPSERT the same tuple
+# - s3: REINDEX concurrent primary key index
+# - s4: operations with injection points
+
+setup
+{
+	CREATE EXTENSION injection_points;
+	CREATE SCHEMA test;
+	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+		FOR VALUES FROM (0) TO (10000)
+		WITH (parallel_workers = 0);
+}
+
+teardown
+{
+	DROP SCHEMA test CASCADE;
+	DROP EXTENSION injection_points;
+}
+
+session s1
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+}
+step s1_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s2
+setup	{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+}
+step s2_start_upsert	{
+	INSERT INTO test.tbl VALUES(13,now()) on conflict(i) do update set updated_at = now();
+}
+
+session s3
+setup	{
+	SELECT injection_points_set_local();
+}
+step s3_setup_wait_before_set_dead {
+	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+}
+step s3_setup_wait_before_swap {
+	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+}
+step s3_start_reindex			{ REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey; }
+
+session s4
+step s4_wakeup_to_swap		{
+	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
+}
+step s4_wakeup_s1		{
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+}
+step s4_wakeup_s2		{
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+}
+step s4_wakeup_to_set_dead		{
+	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
+	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
+}
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_set_dead
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_s2
+
+permutation
+	s3_setup_wait_before_swap
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s4_wakeup_to_swap
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s2
+	s4_wakeup_s1
+
+permutation
+	s3_setup_wait_before_set_dead
+	s3_start_reindex(s1_start_upsert, s2_start_upsert)
+	s1_start_upsert
+	s2_start_upsert(s1_start_upsert)
+	s4_wakeup_s1
+	s4_wakeup_to_set_dead
+	s4_wakeup_s2
\ No newline at end of file
-- 
2.43.0

Subject: [PATCH] Test output variant for CATCACHE_FORCE_RELEASE
---
Index: src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
new file mode 100644
--- /dev/null	(revision faa03762de3e3f0ce3cbeea8d0e0c8f148e449eb)
+++ b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out	(revision faa03762de3e3f0ce3cbeea8d0e0c8f148e449eb)
@@ -0,0 +1,124 @@
+Parsed test spec with 5 sessions
+
+starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s1_attach_invalidate_catalog_snapshot: 
+	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+ <waiting ...>
+step s4_wakeup_s1_setup: 
+	SELECT CASE WHEN
+			(SELECT pid FROM pg_stat_activity
+			      WHERE wait_event_type = 'InjectionPoint' AND
+			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
+			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
+		END;
+
+case
+----
+    
+(1 row)
+
+step s1_attach_invalidate_catalog_snapshot: <... completed>
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: 
+	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
+ <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define-index-before-set-valid');
+	SELECT injection_points_wakeup('define-index-before-set-valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
+	DO $$
+		DECLARE
+			v_waiting_pid INTEGER;
+		BEGIN
+		LOOP
+			SELECT pid INTO v_waiting_pid
+			  FROM pg_stat_activity
+			 WHERE wait_event_type = 'InjectionPoint'
+				   AND wait_event = 'invalidate-catalog-snapshot-end'
+			 LIMIT 1;
+			EXIT WHEN v_waiting_pid IS NOT NULL;
+			PERFORM pg_sleep(100);
+		END LOOP;
+		END
+	$$;
+
+	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
+	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>
Index: src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out b/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
new file mode 100644
--- /dev/null	(revision faa03762de3e3f0ce3cbeea8d0e0c8f148e449eb)
+++ b/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out	(revision faa03762de3e3f0ce3cbeea8d0e0c8f148e449eb)
@@ -0,0 +1,124 @@
+Parsed test spec with 5 sessions
+
+starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s1_attach_invalidate_catalog_snapshot: 
+	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+ <waiting ...>
+step s4_wakeup_s1_setup: 
+	SELECT CASE WHEN
+			(SELECT pid FROM pg_stat_activity
+				  WHERE wait_event_type = 'InjectionPoint' AND
+				  wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
+			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
+		END;
+
+case
+----
+    
+(1 row)
+
+step s1_attach_invalidate_catalog_snapshot: <... completed>
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step s3_start_create_index: 
+	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
+ <waiting ...>
+step s1_start_upsert: 
+	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s4_wakeup_define_index_before_set_valid: 
+	SELECT injection_points_detach('define-index-before-set-valid');
+	SELECT injection_points_wakeup('define-index-before-set-valid');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s2_start_upsert: 
+	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+ <waiting ...>
+step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
+	DO $$
+		DECLARE
+			v_waiting_pid INTEGER;
+		BEGIN
+		LOOP
+			SELECT pid INTO v_waiting_pid
+			  FROM pg_stat_activity
+			 WHERE wait_event_type = 'InjectionPoint'
+				   AND wait_event = 'invalidate-catalog-snapshot-end'
+			 LIMIT 1;
+			EXIT WHEN v_waiting_pid IS NOT NULL;
+			PERFORM pg_sleep(100);
+		END LOOP;
+		END
+	$$;
+
+	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
+	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s2: 
+	SELECT injection_points_detach('exec-insert-before-insert-speculative');
+	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s4_wakeup_s1: 
+	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
+	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step s1_start_upsert: <... completed>
+step s2_start_upsert: <... completed>
+step s3_start_create_index: <... completed>

Subject: [PATCH] more test stabilization
---
Index: src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec
--- a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec	(revision 6bd469d26aca6ea413b35bfcb611dfa3a8f5ea45)
+++ b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec	(date 1764870936317)
@@ -85,7 +85,7 @@
 permutation
 	s3_setup_wait_before_set_dead
 	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
+	s1_start_upsert(s4_wakeup_s2)
 	s4_wakeup_to_set_dead
 	s2_start_upsert(s1_start_upsert)
 	s4_wakeup_s1
@@ -94,7 +94,7 @@
 permutation
 	s3_setup_wait_before_swap
 	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
+	s1_start_upsert(s4_wakeup_s2)
 	s4_wakeup_to_swap
 	s2_start_upsert(s1_start_upsert)
 	s4_wakeup_s2
@@ -103,7 +103,7 @@
 permutation
 	s3_setup_wait_before_set_dead
 	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
+	s1_start_upsert(s4_wakeup_s2)
 	s2_start_upsert(s1_start_upsert)
 	s4_wakeup_s1
 	s4_wakeup_to_set_dead
Index: src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec
--- a/src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec	(revision 6bd469d26aca6ea413b35bfcb611dfa3a8f5ea45)
+++ b/src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec	(date 1764870872510)
@@ -86,7 +86,7 @@
 permutation
 	s3_setup_wait_before_set_dead
 	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
+	s1_start_upsert(s4_wakeup_s2)
 	s4_wakeup_to_set_dead
 	s2_start_upsert(s1_start_upsert)
 	s4_wakeup_s1
@@ -95,7 +95,7 @@
 permutation
 	s3_setup_wait_before_swap
 	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
+	s1_start_upsert(s4_wakeup_s2)
 	s4_wakeup_to_swap
 	s2_start_upsert(s1_start_upsert)
 	s4_wakeup_s2
@@ -104,7 +104,7 @@
 permutation
 	s3_setup_wait_before_set_dead
 	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
+	s1_start_upsert(s4_wakeup_s2)
 	s2_start_upsert(s1_start_upsert)
 	s4_wakeup_s1
 	s4_wakeup_to_set_dead
Index: src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
--- a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec	(revision 6bd469d26aca6ea413b35bfcb611dfa3a8f5ea45)
+++ b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec	(date 1764870936340)
@@ -88,7 +88,7 @@
 permutation
 	s3_setup_wait_before_set_dead
 	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
+	s1_start_upsert(s4_wakeup_s2)
 	s4_wakeup_to_set_dead
 	s2_start_upsert(s1_start_upsert)
 	s4_wakeup_s1
@@ -97,7 +97,7 @@
 permutation
 	s3_setup_wait_before_swap
 	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
+	s1_start_upsert(s4_wakeup_s2)
 	s4_wakeup_to_swap
 	s2_start_upsert(s1_start_upsert)
 	s4_wakeup_s2
@@ -106,7 +106,7 @@
 permutation
 	s3_setup_wait_before_set_dead
 	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
+	s1_start_upsert(s4_wakeup_s2)
 	s2_start_upsert(s1_start_upsert)
 	s4_wakeup_s1
 	s4_wakeup_to_set_dead

From de4fcbcbd35912cea70f0f00f81878ea8b94416c Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <nkey@toloka.ai>
Date: Tue, 9 Dec 2025 19:39:06 +0100
Subject: [PATCH v1] Fix infer_arbiter_index for partitioned tables
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The fix for concurrent index operations in bc32a12e0db started considering indexes that are not yet marked indisvalid. However, for partitioned tables this is incorrect because partitioned tables don't store data themselves; the actual arbiter indexes are inferred later at the leaf partition level.  Considering non-valid indexes on partitioned tables (such as those created with CREATE INDEX ... ON ONLY) led to incorrect arbiter selection and resulted in an error.

Skip non-valid indexes when processing partitioned tables, restoring the previous behavior for them while preserving the concurrent index operation fix for regular tables.

Author: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Discussion: https://postgr.es/m/17622f79-117a-4a44-aa8e-0374e53faaf0%40gmail.com
---
 src/backend/optimizer/util/plancat.c         | 7 ++++++-
 src/test/regress/expected/partition_info.out | 7 +++++++
 src/test/regress/sql/partition_info.sql      | 8 ++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index ed0dac37f51..4775669f868 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -995,8 +995,13 @@ infer_arbiter_indexes(PlannerInfo *root)
 		 * wouldn't detect possible duplicate rows.  In order to prevent false
 		 * negatives, we require that we include in the set of inferred
 		 * indexes at least one index that is marked valid.
+		 *
+		 * Also, in the case of partitioned table - only valid indexes are
+		 * considered because real arbiters inferred later.
 		 */
-		if (!idxForm->indisready)
+		if (!idxForm->indisready ||
+				(relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
+					!idxForm->indisvalid))
 			continue;
 
 		/*
diff --git a/src/test/regress/expected/partition_info.out b/src/test/regress/expected/partition_info.out
index 42b6bc77cad..4defa66e5b3 100644
--- a/src/test/regress/expected/partition_info.out
+++ b/src/test/regress/expected/partition_info.out
@@ -349,3 +349,10 @@ SELECT pg_partition_root('ptif_li_child');
 DROP VIEW ptif_test_view;
 DROP MATERIALIZED VIEW ptif_test_matview;
 DROP TABLE ptif_li_parent, ptif_li_child;
+-- Test about selection of arbiter indexes for partitioned tables with
+-- non-valid index on the parent table
+CREATE TABLE pt (a int PRIMARY KEY) PARTITION BY RANGE (a);
+CREATE TABLE p1 PARTITION OF pt FOR VALUES FROM (1) to (2) PARTITION BY RANGE (a);
+CREATE TABLE p1_1 PARTITION OF p1 FOR VALUES FROM (1) TO (2);
+CREATE UNIQUE INDEX ON ONLY p1 (a);
+INSERT INTO p1 VALUES (1) ON CONFLICT (a) DO NOTHING;
diff --git a/src/test/regress/sql/partition_info.sql b/src/test/regress/sql/partition_info.sql
index b5060bec7f0..2ef65292bab 100644
--- a/src/test/regress/sql/partition_info.sql
+++ b/src/test/regress/sql/partition_info.sql
@@ -127,3 +127,11 @@ SELECT pg_partition_root('ptif_li_child');
 DROP VIEW ptif_test_view;
 DROP MATERIALIZED VIEW ptif_test_matview;
 DROP TABLE ptif_li_parent, ptif_li_child;
+
+-- Test about selection of arbiter indexes for partitioned tables with
+-- non-valid index on the parent table
+CREATE TABLE pt (a int PRIMARY KEY) PARTITION BY RANGE (a);
+CREATE TABLE p1 PARTITION OF pt FOR VALUES FROM (1) to (2) PARTITION BY RANGE (a);
+CREATE TABLE p1_1 PARTITION OF p1 FOR VALUES FROM (1) TO (2);
+CREATE UNIQUE INDEX ON ONLY p1 (a);
+INSERT INTO p1 VALUES (1) ON CONFLICT (a) DO NOTHING;
-- 
2.52.0

From a26caa0ea6a1c9e7eb325fb7e9bd00c43bab4476 Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Sat, 13 Dec 2025 19:42:52 +0100
Subject: [PATCH vnocfbot] Preserve visibility information of the concurrent
 data changes.

As explained in the commit message of the preceding patch of the series, the
data changes done by applications while REPACK CONCURRENTLY is copying the
table contents to a new file are decoded from WAL and eventually also applied
to the new file. To reduce the complexity a little bit, the preceding patch
uses the current transaction (i.e. transaction opened by the REPACK command)
to execute those INSERT, UPDATE and DELETE commands.

However, REPACK is not expected to change visibility of tuples. Therefore,
this patch fixes the handling of the "concurrent data changes". It ensures
that tuples written into the new table have the same XID and command ID (CID)
as they had in the old table.

To "replay" an UPDATE or DELETE command on the new table, we use SnapshotSelf to find the last alive version of tuple and update with stamp with xid of original transaction. It is safe because:
* all transactions we replaying are committed
* apply worker working without any concurrent modifiers of the table

As long as we preserve the tuple visibility information (which includes XID),
it's important to avoid logical decoding of the WAL generated by DMLs on the
new table: the logical decoding subsystem probably does not expect that the
incoming WAL records contain XIDs of an already decoded transactions. (And of
course, repeated decoding would be wasted effort.)

Author: Antonin Houska <ah@cybertec.at> with changes from Mikhail Nikalayeu <mihailnikalayeu@gmail.com
---
 contrib/amcheck/meson.build                   |   1 +
 contrib/amcheck/t/007_repack_concurrently.pl  |   2 +-
 contrib/amcheck/t/008_repack_concurrently.pl  |   2 +-
 .../amcheck/t/009_repack_concurrently_mvcc.pl | 111 ++++++++++++++++++
 doc/src/sgml/mvcc.sgml                        |  12 +-
 doc/src/sgml/ref/repack.sgml                  |   9 --
 src/backend/access/common/toast_internals.c   |   3 +-
 src/backend/access/heap/heapam.c              |  29 +++--
 src/backend/access/heap/heapam_handler.c      |  24 ++--
 src/backend/commands/cluster.c                | 107 ++++++++++++-----
 .../pgoutput_repack/pgoutput_repack.c         |  16 ++-
 src/include/access/heapam.h                   |   6 +-
 .../injection_points/specs/repack.spec        |   4 -
 13 files changed, 243 insertions(+), 83 deletions(-)
 create mode 100644 contrib/amcheck/t/009_repack_concurrently_mvcc.pl

diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index f7c70735989..6946c684259 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -52,6 +52,7 @@ tests += {
       't/006_verify_gin.pl',
       't/007_repack_concurrently.pl',
       't/008_repack_concurrently.pl',
+      't/009_repack_concurrently_mvcc.pl',
     ],
   },
 }
diff --git a/contrib/amcheck/t/007_repack_concurrently.pl b/contrib/amcheck/t/007_repack_concurrently.pl
index a47cebb347b..57769097af9 100644
--- a/contrib/amcheck/t/007_repack_concurrently.pl
+++ b/contrib/amcheck/t/007_repack_concurrently.pl
@@ -91,7 +91,7 @@ $node->pgbench(
 			COMMIT;
 
 			BEGIN
-			--TRANSACTION ISOLATION LEVEL REPEATABLE READ
+			TRANSACTION ISOLATION LEVEL REPEATABLE READ
 			;
 			SELECT 1;
 			\\sleep 1 ms
diff --git a/contrib/amcheck/t/008_repack_concurrently.pl b/contrib/amcheck/t/008_repack_concurrently.pl
index 220524d41b3..14db7425ae4 100644
--- a/contrib/amcheck/t/008_repack_concurrently.pl
+++ b/contrib/amcheck/t/008_repack_concurrently.pl
@@ -82,7 +82,7 @@ $node->pgbench(
 			\\sleep 1 ms
 
 			BEGIN
-			--TRANSACTION ISOLATION LEVEL REPEATABLE READ
+			TRANSACTION ISOLATION LEVEL REPEATABLE READ
 			;
 			SELECT 1;
 			\\sleep 1 ms
diff --git a/contrib/amcheck/t/009_repack_concurrently_mvcc.pl b/contrib/amcheck/t/009_repack_concurrently_mvcc.pl
new file mode 100644
index 00000000000..c0f8a63cf3d
--- /dev/null
+++ b/contrib/amcheck/t/009_repack_concurrently_mvcc.pl
@@ -0,0 +1,111 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+# Test REPACK CONCURRENTLY with concurrent modifications
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('CIC_test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->append_conf(
+	'postgresql.conf', qq(
+wal_level = logical
+));
+$node->start;
+$node->safe_psql('postgres', q(CREATE TABLE tbl1(i int PRIMARY KEY, j int)));
+$node->safe_psql('postgres', q(CREATE TABLE tbl2(i int PRIMARY KEY, j int)));
+
+
+# Insert 100 rows into tbl1
+$node->safe_psql('postgres', q(
+    INSERT INTO tbl1 SELECT i, i % 100 FROM generate_series(1,100) i
+));
+
+# Insert 100 rows into tbl2
+$node->safe_psql('postgres', q(
+    INSERT INTO tbl2 SELECT i, i % 100 FROM generate_series(1,100) i
+));
+
+$node->safe_psql('postgres', q(
+	CREATE OR REPLACE FUNCTION log_raise(i int, j1 int, j2 int) RETURNS VOID AS $$
+	BEGIN
+	  RAISE NOTICE 'ERROR i=% j1=% j2=%', i, j1, j2;
+	END;$$ LANGUAGE plpgsql;
+));
+
+$node->safe_psql('postgres', q(CREATE UNLOGGED SEQUENCE in_row_rebuild START 1 INCREMENT 1;));
+$node->safe_psql('postgres', q(SELECT nextval('in_row_rebuild');));
+
+
+$node->pgbench(
+'--no-vacuum --client=10 --jobs=4 --exit-on-abort --transactions=2500',
+0,
+[qr{actually processed}],
+[qr{^$}],
+'concurrent operations with REINDEX/CREATE INDEX CONCURRENTLY',
+{
+	'concurrent_ops' => q(
+		SELECT pg_try_advisory_lock(42)::integer AS gotlock \gset
+		\if :gotlock
+			SELECT nextval('in_row_rebuild') AS last_value \gset
+			\if :last_value = 2
+				REPACK (CONCURRENTLY) tbl1 USING INDEX tbl1_pkey;
+				\sleep 10 ms
+				REPACK (CONCURRENTLY) tbl2 USING INDEX tbl2_pkey;
+				\sleep 10 ms
+			\endif
+			SELECT pg_advisory_unlock(42);
+		\else
+			\set num random(1, 100)
+			BEGIN;
+			UPDATE tbl1 SET j = j + 1 WHERE i = :num;
+			\sleep 1 ms
+			UPDATE tbl1 SET j = j + 2 WHERE i = :num;
+			\sleep 1 ms
+			UPDATE tbl1 SET j = j + 3 WHERE i = :num;
+			\sleep 1 ms
+			UPDATE tbl1 SET j = j + 4 WHERE i = :num;
+			\sleep 1 ms
+
+			UPDATE tbl2 SET j = j + 1 WHERE i = :num;
+			\sleep 1 ms
+			UPDATE tbl2 SET j = j + 2 WHERE i = :num;
+			\sleep 1 ms
+			UPDATE tbl2 SET j = j + 3 WHERE i = :num;
+			\sleep 1 ms
+			UPDATE tbl2 SET j = j + 4 WHERE i = :num;
+
+			COMMIT;
+			SELECT setval('in_row_rebuild', 1);
+
+			BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+			SELECT COALESCE(SUM(j), 0) AS t1 FROM tbl1 WHERE i = :num \gset p_
+			\sleep 10 ms
+			SELECT COALESCE(SUM(j), 0) AS t2 FROM tbl2 WHERE i = :num \gset p_
+			\if :p_t1 != :p_t2
+				COMMIT;
+				SELECT log_raise(tbl1.i, tbl1.j, tbl2.j) FROM tbl1 LEFT OUTER JOIN tbl2 ON tbl1.i = tbl2.i WHERE tbl1.j != tbl2.j;
+				\sleep 10 ms
+				SELECT log_raise(tbl1.i, tbl1.j, tbl2.j) FROM tbl1 LEFT OUTER JOIN tbl2 ON tbl1.i = tbl2.i WHERE tbl1.j != tbl2.j;
+				SELECT (:p_t1 + :p_t2) / 0;
+			\endif
+
+			COMMIT;
+		\endif
+	)
+});
+
+$node->stop;
+done_testing();
diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml
index 0f5c34af542..049ee75a4ba 100644
--- a/doc/src/sgml/mvcc.sgml
+++ b/doc/src/sgml/mvcc.sgml
@@ -1833,17 +1833,15 @@ SELECT pg_advisory_lock(q.id) FROM
    <title>Caveats</title>
 
    <para>
-    Some commands, currently only <link linkend="sql-truncate"><command>TRUNCATE</command></link>, the
-    table-rewriting forms of <link linkend="sql-altertable"><command>ALTER
-    TABLE</command></link> and <command>REPACK</command> with
-    the <literal>CONCURRENTLY</literal> option, are not
+    Some DDL commands, currently only <link linkend="sql-truncate"><command>TRUNCATE</command></link> and the
+    table-rewriting forms of <link linkend="sql-altertable"><command>ALTER TABLE</command></link>, are not
     MVCC-safe.  This means that after the truncation or rewrite commits, the
     table will appear empty to concurrent transactions, if they are using a
-    snapshot taken before the command committed.  This will only be an
+    snapshot taken before the DDL command committed.  This will only be an
     issue for a transaction that did not access the table in question
-    before the command started &mdash; any transaction that has done so
+    before the DDL command started &mdash; any transaction that has done so
     would hold at least an <literal>ACCESS SHARE</literal> table lock,
-    which would block the truncating or rewriting command until that transaction completes.
+    which would block the DDL command until that transaction completes.
     So these commands will not cause any apparent inconsistency in the
     table contents for successive queries on the target table, but they
     could cause visible inconsistency between the contents of the target
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index 30c43c49069..9796a923597 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -308,15 +308,6 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
        </listitem>
       </itemizedlist>
      </para>
-
-     <warning>
-      <para>
-       <command>REPACK</command> with the <literal>CONCURRENTLY</literal>
-       option is not MVCC-safe, see <xref linkend="mvcc-caveats"/> for
-       details.
-      </para>
-     </warning>
-
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
index 63b848473f8..91119da5cd5 100644
--- a/src/backend/access/common/toast_internals.c
+++ b/src/backend/access/common/toast_internals.c
@@ -311,7 +311,8 @@ toast_save_datum(Relation rel, Datum value,
 
 		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
 
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
+		heap_insert(toastrel, toasttup, GetCurrentTransactionId(), mycid,
+					options, NULL);
 
 		/*
 		 * Create the index entry.  We cheat a little here by not using
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index e11833f01b4..94ca07e4b55 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2085,7 +2085,7 @@ ReleaseBulkInsertStatePin(BulkInsertState bistate)
 /*
  *	heap_insert		- insert tuple into a heap
  *
- * The new tuple is stamped with current transaction ID and the specified
+ * The new tuple is stamped with specified transaction ID and the specified
  * command ID.
  *
  * See table_tuple_insert for comments about most of the input flags, except
@@ -2101,15 +2101,16 @@ ReleaseBulkInsertStatePin(BulkInsertState bistate)
  * reflected into *tup.
  */
 void
-heap_insert(Relation relation, HeapTuple tup, CommandId cid,
-			int options, BulkInsertState bistate)
+heap_insert(Relation relation, HeapTuple tup, TransactionId xid,
+			CommandId cid, int options, BulkInsertState bistate)
 {
-	TransactionId xid = GetCurrentTransactionId();
 	HeapTuple	heaptup;
 	Buffer		buffer;
 	Buffer		vmbuffer = InvalidBuffer;
 	bool		all_visible_cleared = false;
 
+	Assert(TransactionIdIsValid(xid));
+
 	/* Cheap, simplistic check that the tuple matches the rel's rowtype. */
 	Assert(HeapTupleHeaderGetNatts(tup->t_data) <=
 		   RelationGetNumberOfAttributes(relation));
@@ -2375,7 +2376,6 @@ void
 heap_multi_insert(Relation relation, TupleTableSlot **slots, int ntuples,
 				  CommandId cid, int options, BulkInsertState bistate)
 {
-	TransactionId xid = GetCurrentTransactionId();
 	HeapTuple  *heaptuples;
 	int			i;
 	int			ndone;
@@ -2408,7 +2408,7 @@ heap_multi_insert(Relation relation, TupleTableSlot **slots, int ntuples,
 		tuple = ExecFetchSlotHeapTuple(slots[i], true, NULL);
 		slots[i]->tts_tableOid = RelationGetRelid(relation);
 		tuple->t_tableOid = slots[i]->tts_tableOid;
-		heaptuples[i] = heap_prepare_insert(relation, tuple, xid, cid,
+		heaptuples[i] = heap_prepare_insert(relation, tuple, GetCurrentTransactionId(), cid,
 											options);
 	}
 
@@ -2746,7 +2746,8 @@ heap_multi_insert(Relation relation, TupleTableSlot **slots, int ntuples,
 void
 simple_heap_insert(Relation relation, HeapTuple tup)
 {
-	heap_insert(relation, tup, GetCurrentCommandId(true), 0, NULL);
+	heap_insert(relation, tup, GetCurrentTransactionId(),
+				GetCurrentCommandId(true), 0, NULL);
 }
 
 /*
@@ -2803,11 +2804,10 @@ xmax_infomask_changed(uint16 new_infomask, uint16 old_infomask)
  */
 TM_Result
 heap_delete(Relation relation, const ItemPointerData *tid,
-			CommandId cid, Snapshot crosscheck, bool wait,
+			TransactionId xid, CommandId cid, Snapshot crosscheck, bool wait,
 			TM_FailureData *tmfd, bool changingPart, bool walLogical)
 {
 	TM_Result	result;
-	TransactionId xid = GetCurrentTransactionId();
 	ItemId		lp;
 	HeapTupleData tp;
 	Page		page;
@@ -2824,6 +2824,7 @@ heap_delete(Relation relation, const ItemPointerData *tid,
 	bool		old_key_copied = false;
 
 	Assert(ItemPointerIsValid(tid));
+	Assert(TransactionIdIsValid(xid));
 
 	AssertHasSnapshotForToast(relation);
 
@@ -3240,7 +3241,7 @@ simple_heap_delete(Relation relation, const ItemPointerData *tid)
 	TM_Result	result;
 	TM_FailureData tmfd;
 
-	result = heap_delete(relation, tid,
+	result = heap_delete(relation, tid, GetCurrentTransactionId(),
 						 GetCurrentCommandId(true), InvalidSnapshot,
 						 true /* wait for commit */ ,
 						 &tmfd, false,	/* changingPart */
@@ -3283,12 +3284,11 @@ simple_heap_delete(Relation relation, const ItemPointerData *tid)
  */
 TM_Result
 heap_update(Relation relation, const ItemPointerData *otid, HeapTuple newtup,
-			CommandId cid, Snapshot crosscheck, bool wait,
+			TransactionId xid, CommandId cid, Snapshot crosscheck, bool wait,
 			TM_FailureData *tmfd, LockTupleMode *lockmode,
 			TU_UpdateIndexes *update_indexes, bool walLogical)
 {
 	TM_Result	result;
-	TransactionId xid = GetCurrentTransactionId();
 	Bitmapset  *hot_attrs;
 	Bitmapset  *sum_attrs;
 	Bitmapset  *key_attrs;
@@ -3328,6 +3328,7 @@ heap_update(Relation relation, const ItemPointerData *otid, HeapTuple newtup,
 				infomask2_new_tuple;
 
 	Assert(ItemPointerIsValid(otid));
+	Assert(TransactionIdIsValid(xid));
 
 	/* Cheap, simplistic check that the tuple matches the rel's rowtype. */
 	Assert(HeapTupleHeaderGetNatts(newtup->t_data) <=
@@ -4534,7 +4535,7 @@ simple_heap_update(Relation relation, const ItemPointerData *otid, HeapTuple tup
 	TM_FailureData tmfd;
 	LockTupleMode lockmode;
 
-	result = heap_update(relation, otid, tup,
+	result = heap_update(relation, otid, tup, GetCurrentTransactionId(),
 						 GetCurrentCommandId(true), InvalidSnapshot,
 						 true /* wait for commit */ ,
 						 &tmfd, &lockmode, update_indexes,
@@ -5373,8 +5374,6 @@ compute_new_xmax_infomask(TransactionId xmax, uint16 old_infomask,
 	uint16		new_infomask,
 				new_infomask2;
 
-	Assert(TransactionIdIsCurrentTransactionId(add_to_xmax));
-
 l5:
 	new_infomask = 0;
 	new_infomask2 = 0;
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index e6d630fa2f7..b49f9add5bb 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -252,7 +252,8 @@ heapam_tuple_insert(Relation relation, TupleTableSlot *slot, CommandId cid,
 	tuple->t_tableOid = slot->tts_tableOid;
 
 	/* Perform the insertion, and copy the resulting ItemPointer */
-	heap_insert(relation, tuple, cid, options, bistate);
+	heap_insert(relation, tuple, GetCurrentTransactionId(), cid, options,
+				bistate);
 	ItemPointerCopy(&tuple->t_self, &slot->tts_tid);
 
 	if (shouldFree)
@@ -275,7 +276,8 @@ heapam_tuple_insert_speculative(Relation relation, TupleTableSlot *slot,
 	options |= HEAP_INSERT_SPECULATIVE;
 
 	/* Perform the insertion, and copy the resulting ItemPointer */
-	heap_insert(relation, tuple, cid, options, bistate);
+	heap_insert(relation, tuple, GetCurrentTransactionId(), cid, options,
+				bistate);
 	ItemPointerCopy(&tuple->t_self, &slot->tts_tid);
 
 	if (shouldFree)
@@ -309,8 +311,8 @@ heapam_tuple_delete(Relation relation, ItemPointer tid, CommandId cid,
 	 * the storage itself is cleaning the dead tuples by itself, it is the
 	 * time to call the index tuple deletion also.
 	 */
-	return heap_delete(relation, tid, cid, crosscheck, wait, tmfd, changingPart,
-					   true);
+	return heap_delete(relation, tid, GetCurrentTransactionId(), cid,
+					   crosscheck, wait, tmfd, changingPart, true);
 }
 
 
@@ -328,7 +330,8 @@ heapam_tuple_update(Relation relation, ItemPointer otid, TupleTableSlot *slot,
 	slot->tts_tableOid = RelationGetRelid(relation);
 	tuple->t_tableOid = slot->tts_tableOid;
 
-	result = heap_update(relation, otid, tuple, cid, crosscheck, wait,
+	result = heap_update(relation, otid, tuple, GetCurrentTransactionId(),
+						 cid, crosscheck, wait,
 						 tmfd, lockmode, update_indexes, true);
 	ItemPointerCopy(&tuple->t_self, &slot->tts_tid);
 
@@ -2441,9 +2444,16 @@ reform_and_rewrite_tuple(HeapTuple tuple,
 		 * flag to skip logical decoding: as soon as REPACK CONCURRENTLY swaps
 		 * the relation files, it drops this relation, so no logical
 		 * replication subscription should need the data.
+		 *
+		 * It is also crucial to stamp the new record with the exact same xid
+		 * and cid, because the tuple must be visible to the snapshots of the
+		 * concurrent transactions later.
 		 */
-		heap_insert(NewHeap, copiedTuple, GetCurrentCommandId(true),
-					HEAP_INSERT_NO_LOGICAL, NULL);
+		// TODO: looks like cid is not required
+		CommandId	cid = HeapTupleHeaderGetRawCommandId(tuple->t_data);
+		TransactionId xid = HeapTupleHeaderGetXmin(tuple->t_data);
+
+		heap_insert(NewHeap, copiedTuple, xid, cid, HEAP_INSERT_NO_LOGICAL, NULL);
 	}
 
 	heap_freetuple(copiedTuple);
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index f2a2ec6d3e5..0b79175f7f4 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -58,6 +58,7 @@
 #include "storage/ipc.h"
 #include "storage/lmgr.h"
 #include "storage/predicate.h"
+#include "storage/procarray.h"
 #include "storage/procsignal.h"
 #include "tcop/tcopprot.h"
 #include "utils/acl.h"
@@ -249,15 +250,20 @@ static bool decode_concurrent_changes(LogicalDecodingContext *ctx,
 									  DecodingWorkerShared *shared);
 static void apply_concurrent_changes(BufFile *file, ChangeDest *dest);
 static void apply_concurrent_insert(Relation rel, HeapTuple tup,
+									TransactionId xid,
 									IndexInsertState *iistate,
 									TupleTableSlot *index_slot);
 static void apply_concurrent_update(Relation rel, HeapTuple tup,
 									HeapTuple tup_target,
+									TransactionId xid,
 									IndexInsertState *iistate,
 									TupleTableSlot *index_slot);
-static void apply_concurrent_delete(Relation rel, HeapTuple tup_target);
+static void apply_concurrent_delete(Relation rel,
+									TransactionId xid,
+									HeapTuple tup_target);
 static HeapTuple find_target_tuple(Relation rel, ChangeDest *dest,
 								   HeapTuple tup_key,
+								   Snapshot snapshot,
 								   TupleTableSlot *ident_slot);
 static void process_concurrent_changes(XLogRecPtr end_of_wal,
 									   ChangeDest *dest,
@@ -1091,7 +1097,14 @@ rebuild_relation(Relation OldHeap, Relation index, bool verbose, bool concurrent
 
 	/* The historic snapshot won't be needed anymore. */
 	if (snapshot)
+	{
+		TransactionId xmin = snapshot->xmin;
 		PopActiveSnapshot();
+		Assert(concurrent);
+		// TODO: seems like it not required: need to check SnapBuildInitialSnapshotForRepack
+		WaitForOlderSnapshots(xmin, false);
+	}
+
 
 	if (concurrent)
 	{
@@ -1382,30 +1395,35 @@ copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex,
 	 * not to be aggressive about this.
 	 */
 	memset(&params, 0, sizeof(VacuumParams));
-	vacuum_get_cutoffs(OldHeap, params, &cutoffs);
-
-	/*
-	 * FreezeXid will become the table's new relfrozenxid, and that mustn't go
-	 * backwards, so take the max.
-	 */
+	if (!concurrent)
 	{
 		TransactionId relfrozenxid = OldHeap->rd_rel->relfrozenxid;
+		MultiXactId relminmxid = OldHeap->rd_rel->relminmxid;
 
+		vacuum_get_cutoffs(OldHeap, params, &cutoffs);
+		/*
+		 * FreezeXid will become the table's new relfrozenxid, and that mustn't go
+		 * backwards, so take the max.
+		 */
 		if (TransactionIdIsValid(relfrozenxid) &&
 			TransactionIdPrecedes(cutoffs.FreezeLimit, relfrozenxid))
 			cutoffs.FreezeLimit = relfrozenxid;
-	}
-
-	/*
-	 * MultiXactCutoff, similarly, shouldn't go backwards either.
-	 */
-	{
-		MultiXactId relminmxid = OldHeap->rd_rel->relminmxid;
-
+		/*
+		 * MultiXactCutoff, similarly, shouldn't go backwards either.
+		 */
 		if (MultiXactIdIsValid(relminmxid) &&
 			MultiXactIdPrecedes(cutoffs.MultiXactCutoff, relminmxid))
 			cutoffs.MultiXactCutoff = relminmxid;
 	}
+	else
+	{
+		/*
+		 * In concurrent mode we reuse all the xmin/xmax,
+		 * so just use current values for simplicity.
+		 */
+		cutoffs.FreezeLimit = OldHeap->rd_rel->relfrozenxid;
+		cutoffs.MultiXactCutoff = OldHeap->rd_rel->relminmxid;
+	}
 
 	/*
 	 * Decide whether to use an indexscan or seqscan-and-optional-sort to scan
@@ -2745,6 +2763,7 @@ apply_concurrent_changes(BufFile *file, ChangeDest *dest)
 		size_t		nread;
 		HeapTuple	tup,
 					tup_exist;
+		TransactionId xid;
 
 		CHECK_FOR_INTERRUPTS();
 
@@ -2761,6 +2780,17 @@ apply_concurrent_changes(BufFile *file, ChangeDest *dest)
 		tup->t_len = t_len;
 		ItemPointerSetInvalid(&tup->t_self);
 		tup->t_tableOid = RelationGetRelid(dest->rel);
+		BufFileReadExact(file, &xid, sizeof(TransactionId));
+
+		if (TransactionIdIsValid(xid) && TransactionIdIsInProgress(xid))
+		{
+			/* xmin is committed for sure because we got that update from reorderbuffer.
+			 * but there is a possibility procarray is not yet updated and current backend still see it as
+			 * in-progress. Let's wait for procarray to be updated. */
+			XactLockTableWait(xid, NULL, NULL, XLTW_None);
+			Assert(!TransactionIdIsInProgress(xid));
+			Assert(TransactionIdDidCommit(xid));
+		}
 
 		if (kind == CHANGE_UPDATE_OLD)
 		{
@@ -2771,7 +2801,7 @@ apply_concurrent_changes(BufFile *file, ChangeDest *dest)
 		{
 			Assert(tup_old == NULL);
 
-			apply_concurrent_insert(rel, tup, dest->iistate, index_slot);
+			apply_concurrent_insert(rel, tup, xid, dest->iistate, index_slot);
 
 			pfree(tup);
 		}
@@ -2790,17 +2820,21 @@ apply_concurrent_changes(BufFile *file, ChangeDest *dest)
 			}
 
 			/*
-			 * Find the tuple to be updated or deleted.
+			 * Find the tuple to be updated or deleted using SnapshotSelf.
+			 * That way we receive the last alive version in case of HOT chain.
+			 * It is guaranteed there is no any non-yet committed, but updated version
+			 * because we here replaying all-committed transactions without any concurrency
+			 * involved.
 			 */
-			tup_exist = find_target_tuple(rel, dest, tup_key, ident_slot);
+			tup_exist = find_target_tuple(rel, dest, tup_key, SnapshotSelf, ident_slot);
 			if (tup_exist == NULL)
 				elog(ERROR, "failed to find target tuple");
 
 			if (kind == CHANGE_UPDATE_NEW)
-				apply_concurrent_update(rel, tup, tup_exist, dest->iistate,
+				apply_concurrent_update(rel, tup, tup_exist, xid, dest->iistate,
 										index_slot);
 			else
-				apply_concurrent_delete(rel, tup_exist);
+				apply_concurrent_delete(rel, xid, tup_exist);
 
 			if (tup_old != NULL)
 			{
@@ -2819,6 +2853,7 @@ apply_concurrent_changes(BufFile *file, ChangeDest *dest)
 		 */
 		if (kind != CHANGE_UPDATE_OLD)
 		{
+			// TODO: not sure it is required at all: we are replaying committed transactions stamping them with committed XID
 			CommandCounterIncrement();
 			UpdateActiveSnapshotCommandId();
 		}
@@ -2830,7 +2865,7 @@ apply_concurrent_changes(BufFile *file, ChangeDest *dest)
 }
 
 static void
-apply_concurrent_insert(Relation rel, HeapTuple tup, IndexInsertState *iistate,
+apply_concurrent_insert(Relation rel, HeapTuple tup, TransactionId xid, IndexInsertState *iistate,
 						TupleTableSlot *index_slot)
 {
 	List	   *recheck;
@@ -2840,9 +2875,12 @@ apply_concurrent_insert(Relation rel, HeapTuple tup, IndexInsertState *iistate,
 	 * Like simple_heap_insert(), but make sure that the INSERT is not
 	 * logically decoded - see reform_and_rewrite_tuple() for more
 	 * information.
+	 *
+	 * Use already committed xid to stamp the tuple.
 	 */
-	heap_insert(rel, tup, GetCurrentCommandId(true), HEAP_INSERT_NO_LOGICAL,
-				NULL);
+	Assert(TransactionIdIsValid(xid));
+	heap_insert(rel, tup, xid, GetCurrentCommandId(true),
+				HEAP_INSERT_NO_LOGICAL, NULL);
 
 	/*
 	 * Update indexes.
@@ -2850,6 +2888,7 @@ apply_concurrent_insert(Relation rel, HeapTuple tup, IndexInsertState *iistate,
 	 * In case functions in the index need the active snapshot and caller
 	 * hasn't set one.
 	 */
+	PushActiveSnapshot(GetLatestSnapshot());
 	ExecStoreHeapTuple(tup, index_slot, false);
 	recheck = ExecInsertIndexTuples(iistate->rri,
 									index_slot,
@@ -2860,6 +2899,7 @@ apply_concurrent_insert(Relation rel, HeapTuple tup, IndexInsertState *iistate,
 									NIL,	/* arbiterIndexes */
 									false	/* onlySummarizing */
 		);
+	PopActiveSnapshot();
 
 	/*
 	 * If recheck is required, it must have been preformed on the source
@@ -2873,6 +2913,7 @@ apply_concurrent_insert(Relation rel, HeapTuple tup, IndexInsertState *iistate,
 
 static void
 apply_concurrent_update(Relation rel, HeapTuple tup, HeapTuple tup_target,
+						TransactionId xid,
 						IndexInsertState *iistate, TupleTableSlot *index_slot)
 {
 	LockTupleMode lockmode;
@@ -2887,9 +2928,12 @@ apply_concurrent_update(Relation rel, HeapTuple tup, HeapTuple tup_target,
 	 *
 	 * Do it like in simple_heap_update(), except for 'wal_logical' (and
 	 * except for 'wait').
+	 *
+	 * Use already committed xid to stamp the tuple.
 	 */
+	Assert(TransactionIdIsValid(xid));
 	res = heap_update(rel, &tup_target->t_self, tup,
-					  GetCurrentCommandId(true),
+					  xid, GetCurrentCommandId(true),
 					  InvalidSnapshot,
 					  false,	/* no wait - only we are doing changes */
 					  &tmfd, &lockmode, &update_indexes,
@@ -2901,6 +2945,7 @@ apply_concurrent_update(Relation rel, HeapTuple tup, HeapTuple tup_target,
 
 	if (update_indexes != TU_None)
 	{
+		PushActiveSnapshot(GetLatestSnapshot());
 		recheck = ExecInsertIndexTuples(iistate->rri,
 										index_slot,
 										iistate->estate,
@@ -2910,6 +2955,7 @@ apply_concurrent_update(Relation rel, HeapTuple tup, HeapTuple tup_target,
 										NIL,	/* arbiterIndexes */
 		/* onlySummarizing */
 										update_indexes == TU_Summarizing);
+		PopActiveSnapshot();
 		list_free(recheck);
 	}
 
@@ -2917,7 +2963,7 @@ apply_concurrent_update(Relation rel, HeapTuple tup, HeapTuple tup_target,
 }
 
 static void
-apply_concurrent_delete(Relation rel, HeapTuple tup_target)
+apply_concurrent_delete(Relation rel, TransactionId xid, HeapTuple tup_target)
 {
 	TM_Result	res;
 	TM_FailureData tmfd;
@@ -2927,9 +2973,12 @@ apply_concurrent_delete(Relation rel, HeapTuple tup_target)
 	 *
 	 * Do it like in simple_heap_delete(), except for 'wal_logical' (and
 	 * except for 'wait').
+	 *
+	 * Use already committed xid to stamp the tuple.
 	 */
-	res = heap_delete(rel, &tup_target->t_self, GetCurrentCommandId(true),
-					  InvalidSnapshot, false,
+	Assert(TransactionIdIsValid(xid));
+	res = heap_delete(rel, &tup_target->t_self, xid,
+					  GetCurrentCommandId(true), InvalidSnapshot, false,
 					  &tmfd,
 					  false,	/* no wait - only we are doing changes */
 					  false /* wal_logical */ );
@@ -2950,7 +2999,7 @@ apply_concurrent_delete(Relation rel, HeapTuple tup_target)
  */
 static HeapTuple
 find_target_tuple(Relation rel, ChangeDest *dest, HeapTuple tup_key,
-				  TupleTableSlot *ident_slot)
+				  Snapshot snapshot, TupleTableSlot *ident_slot)
 {
 	Relation	ident_index = dest->ident_index;
 	IndexScanDesc scan;
@@ -2959,7 +3008,7 @@ find_target_tuple(Relation rel, ChangeDest *dest, HeapTuple tup_key,
 	HeapTuple	result = NULL;
 
 	/* XXX no instrumentation for now */
-	scan = index_beginscan(rel, ident_index, GetActiveSnapshot(),
+	scan = index_beginscan(rel, ident_index, snapshot,
 						   NULL, dest->ident_key_nentries, 0);
 
 	/*
diff --git a/src/backend/replication/pgoutput_repack/pgoutput_repack.c b/src/backend/replication/pgoutput_repack/pgoutput_repack.c
index fb9956d392d..8d796e0a684 100644
--- a/src/backend/replication/pgoutput_repack/pgoutput_repack.c
+++ b/src/backend/replication/pgoutput_repack/pgoutput_repack.c
@@ -29,7 +29,8 @@ static void plugin_commit_txn(LogicalDecodingContext *ctx,
 static void plugin_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 						  Relation rel, ReorderBufferChange *change);
 static void store_change(LogicalDecodingContext *ctx,
-						 ConcurrentChangeKind kind, HeapTuple tuple);
+						 ConcurrentChangeKind kind, HeapTuple tuple,
+						 TransactionId xid);
 
 void
 _PG_output_plugin_init(OutputPluginCallbacks *cb)
@@ -120,7 +121,7 @@ plugin_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 				if (newtuple == NULL)
 					elog(ERROR, "Incomplete insert info.");
 
-				store_change(ctx, CHANGE_INSERT, newtuple);
+				store_change(ctx, CHANGE_INSERT, newtuple, change->txn->xid);
 			}
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
@@ -137,9 +138,11 @@ plugin_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 					elog(ERROR, "Incomplete update info.");
 
 				if (oldtuple != NULL)
-					store_change(ctx, CHANGE_UPDATE_OLD, oldtuple);
+					store_change(ctx, CHANGE_UPDATE_OLD, oldtuple,
+								 change->txn->xid);
 
-				store_change(ctx, CHANGE_UPDATE_NEW, newtuple);
+				store_change(ctx, CHANGE_UPDATE_NEW, newtuple,
+							 change->txn->xid);
 			}
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
@@ -152,7 +155,7 @@ plugin_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 				if (oldtuple == NULL)
 					elog(ERROR, "Incomplete delete info.");
 
-				store_change(ctx, CHANGE_DELETE, oldtuple);
+				store_change(ctx, CHANGE_DELETE, oldtuple, change->txn->xid);
 			}
 			break;
 		default:
@@ -165,7 +168,7 @@ plugin_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 /* Store concurrent data change. */
 static void
 store_change(LogicalDecodingContext *ctx, ConcurrentChangeKind kind,
-			 HeapTuple tuple)
+			 HeapTuple tuple, TransactionId xid)
 {
 	RepackDecodingState *dstate;
 	char		kind_byte = (char) kind;
@@ -195,6 +198,7 @@ store_change(LogicalDecodingContext *ctx, ConcurrentChangeKind kind,
 	BufFileWrite(dstate->file, &tuple->t_len, sizeof(tuple->t_len));
 	/* ... and the tuple itself. */
 	BufFileWrite(dstate->file, tuple->t_data, tuple->t_len);
+	BufFileWrite(dstate->file, &xid, sizeof(TransactionId));
 
 	/* Free the flat copy if created above. */
 	if (flattened)
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index b7cd25896f6..d9776f61a0d 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -354,20 +354,20 @@ extern BulkInsertState GetBulkInsertState(void);
 extern void FreeBulkInsertState(BulkInsertState);
 extern void ReleaseBulkInsertStatePin(BulkInsertState bistate);
 
-extern void heap_insert(Relation relation, HeapTuple tup, CommandId cid,
+extern void heap_insert(Relation relation, HeapTuple tup, TransactionId xid, CommandId cid,
 						int options, BulkInsertState bistate);
 extern void heap_multi_insert(Relation relation, TupleTableSlot **slots,
 							  int ntuples, CommandId cid, int options,
 							  BulkInsertState bistate);
 extern TM_Result heap_delete(Relation relation, const ItemPointerData *tid,
-							 CommandId cid, Snapshot crosscheck, bool wait,
+							 TransactionId xid, CommandId cid, Snapshot crosscheck, bool wait,
 							 TM_FailureData *tmfd, bool changingPart,
 							 bool wal_logical);
 extern void heap_finish_speculative(Relation relation, const ItemPointerData *tid);
 extern void heap_abort_speculative(Relation relation, const ItemPointerData *tid);
 extern TM_Result heap_update(Relation relation, const ItemPointerData *otid,
 							 HeapTuple newtup,
-							 CommandId cid, Snapshot crosscheck, bool wait,
+							 TransactionId xid, CommandId cid, Snapshot crosscheck, bool wait,
 							 TM_FailureData *tmfd, LockTupleMode *lockmode,
 							 TU_UpdateIndexes *update_indexes, bool wal_logical);
 extern TM_Result heap_lock_tuple(Relation relation, HeapTuple tuple,
diff --git a/src/test/modules/injection_points/specs/repack.spec b/src/test/modules/injection_points/specs/repack.spec
index d727a9b056b..accd42d78aa 100644
--- a/src/test/modules/injection_points/specs/repack.spec
+++ b/src/test/modules/injection_points/specs/repack.spec
@@ -85,9 +85,6 @@ step change_new
 # When applying concurrent data changes, we should see the effects of an
 # in-progress subtransaction.
 #
-# XXX Not sure this test is useful now - it was designed for the patch that
-# preserves tuple visibility and which therefore modifies
-# TransactionIdIsCurrentTransactionId().
 step change_subxact1
 {
 	BEGIN;
@@ -102,7 +99,6 @@ step change_subxact1
 # When applying concurrent data changes, we should not see the effects of a
 # rolled back subtransaction.
 #
-# XXX Is this test useful? See above.
 step change_subxact2
 {
 	BEGIN;
-- 
2.43.0

From f532028260b8da0697772d0f5c0c16c58fc15f02 Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Mon, 15 Dec 2025 12:03:04 +0100
Subject: [PATCH vnocfbo2] Replace flaky isolation tests with a TAP test for
 concurrent upserts

The isolation tests verifying INSERT ON CONFLICT behavior during
concurrent index creation/reindexing were prone to flakiness. The
timing dependencies on injection points were difficult to guarantee
in the isolation tester.

Remove the disabled isolation tests and their specs/expected output.
Add TAP test '010_index_concurrently_upsert.pl' to
cover these scenarios more reliably. The TAP test now includes better
session management and more robust injection point
waiting logic.
---
 src/test/modules/injection_points/Makefile    |   8 -
 .../index-concurrently-upsert-predicate.out   | 123 ---
 .../index-concurrently-upsert-predicate_1.out | 124 ---
 .../expected/index-concurrently-upsert.out    | 123 ---
 .../expected/index-concurrently-upsert_1.out  | 124 ---
 ...ndex-concurrently-upsert-on-constraint.out | 238 -----
 ...eindex-concurrently-upsert-partitioned.out | 238 -----
 .../expected/reindex-concurrently-upsert.out  | 238 -----
 src/test/modules/injection_points/meson.build |   6 -
 .../index-concurrently-upsert-predicate.spec  | 124 ---
 .../specs/index-concurrently-upsert.spec      | 123 ---
 ...dex-concurrently-upsert-on-constraint.spec | 110 ---
 ...index-concurrently-upsert-partitioned.spec | 113 ---
 .../specs/reindex-concurrently-upsert.spec    | 111 ---
 src/test/modules/test_misc/Makefile           |   3 +
 src/test/modules/test_misc/meson.build        |   3 +
 .../t/010_index_concurrently_upsert.pl        | 894 ++++++++++++++++++
 17 files changed, 900 insertions(+), 1803 deletions(-)
 delete mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
 delete mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
 delete mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert.out
 delete mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
 delete mode 100644 src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out
 delete mode 100644 src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
 delete mode 100644 src/test/modules/injection_points/expected/reindex-concurrently-upsert.out
 delete mode 100644 src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
 delete mode 100644 src/test/modules/injection_points/specs/index-concurrently-upsert.spec
 delete mode 100644 src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec
 delete mode 100644 src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
 delete mode 100644 src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec
 create mode 100644 src/test/modules/test_misc/t/010_index_concurrently_upsert.pl

diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index bfdb3f53377..3cb50d13e52 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -16,14 +16,6 @@ ISOLATION = basic \
 	    inplace \
 	    syscache-update-pruned
 
-# Temporarily disabled because of flakiness
-#ISOLATION =+
-#	    index-concurrently-upsert \
-#	    index-concurrently-upsert-predicate \
-#	    reindex-concurrently-upsert \
-#	    reindex-concurrently-upsert-on-constraint \
-#	    reindex-concurrently-upsert-partitioned
-
 # The injection points are cluster-wide, so disable installcheck
 NO_INSTALLCHECK = 1
 
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
deleted file mode 100644
index 77e7d1a7815..00000000000
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
+++ /dev/null
@@ -1,123 +0,0 @@
-Parsed test spec with 5 sessions
-
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: 
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1_setup: 
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-			      WHERE wait_event_type = 'InjectionPoint' AND
-			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-
-case
-----
-    
-(1 row)
-
-step s3_start_create_index: 
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_define_index_before_set_valid: 
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
deleted file mode 100644
index e72848d6a78..00000000000
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
+++ /dev/null
@@ -1,124 +0,0 @@
-Parsed test spec with 5 sessions
-
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: 
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
- <waiting ...>
-step s4_wakeup_s1_setup: 
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-			      WHERE wait_event_type = 'InjectionPoint' AND
-			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-
-case
-----
-    
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: <... completed>
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_create_index: 
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_define_index_before_set_valid: 
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert.out b/src/test/modules/injection_points/expected/index-concurrently-upsert.out
deleted file mode 100644
index a2ef122625c..00000000000
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert.out
+++ /dev/null
@@ -1,123 +0,0 @@
-Parsed test spec with 5 sessions
-
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: 
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1_setup: 
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-				  WHERE wait_event_type = 'InjectionPoint' AND
-				  wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-
-case
-----
-    
-(1 row)
-
-step s3_start_create_index: 
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_define_index_before_set_valid: 
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out b/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
deleted file mode 100644
index ee3b6641b90..00000000000
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
+++ /dev/null
@@ -1,124 +0,0 @@
-Parsed test spec with 5 sessions
-
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: 
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
- <waiting ...>
-step s4_wakeup_s1_setup: 
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-				  WHERE wait_event_type = 'InjectionPoint' AND
-				  wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-
-case
-----
-    
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: <... completed>
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_create_index: 
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_define_index_before_set_valid: 
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out b/src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out
deleted file mode 100644
index c1ac1f77c61..00000000000
--- a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out
+++ /dev/null
@@ -1,238 +0,0 @@
-Parsed test spec with 4 sessions
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_swap: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_swap: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out b/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
deleted file mode 100644
index 4c79a43d986..00000000000
--- a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
+++ /dev/null
@@ -1,238 +0,0 @@
-Parsed test spec with 4 sessions
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_swap: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_swap: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex-concurrently-upsert.out b/src/test/modules/injection_points/expected/reindex-concurrently-upsert.out
deleted file mode 100644
index c9cc9989d02..00000000000
--- a/src/test/modules/injection_points/expected/reindex-concurrently-upsert.out
+++ /dev/null
@@ -1,238 +0,0 @@
-Parsed test spec with 4 sessions
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_swap: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_swap: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 493e11053dc..2c6cf54a33e 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -46,12 +46,6 @@ tests += {
       'basic',
       'inplace',
       'syscache-update-pruned',
-      # temporarily disabled because of flakiness
-      # 'index-concurrently-upsert',
-      # 'index-concurrently-upsert-predicate',
-      # 'reindex-concurrently-upsert',
-      # 'reindex-concurrently-upsert-on-constraint',
-      # 'reindex-concurrently-upsert-partitioned',
     ],
     'runningcheck': false, # see syscache-update-pruned
     # Some tests wait for all snapshots, so avoid parallel execution
diff --git a/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec b/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
deleted file mode 100644
index d9b8d27fd1f..00000000000
--- a/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
+++ /dev/null
@@ -1,124 +0,0 @@
-# This test verifies INSERT ON CONFLICT DO UPDATE behavior concurrent with
-# CREATE INDEX CONCURRENTLY a partial index.
-#
-# - s1: UPSERT a tuple
-# - s2: UPSERT the same tuple
-# - s3: CREATE UNIQUE INDEX CONCURRENTLY (with a predicate)
-#
-# - s4 and s5: control concurrency via injection points
-
-setup
-{
-	CREATE EXTENSION injection_points;
-	CREATE SCHEMA test;
-	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
-	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
-	ALTER TABLE test.tbl SET (parallel_workers=0);
-}
-
-teardown
-{
-	DROP SCHEMA test CASCADE;
-	DROP EXTENSION injection_points;
-}
-
-session s1
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-}
-step s1_attach_invalidate_catalog_snapshot
-{
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-}
-step s1_start_upsert
-{
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
-}
-
-session s2
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
-}
-step s2_start_upsert
-{
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
-}
-
-session s3
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('define-index-before-set-valid', 'wait');
-}
-step s3_start_create_index
-{
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
-}
-
-session s4
-# Step s1_attach_invalidate_catalog_snapshot sleeps or not depending on
-# build conditions (CATCACHE_FORCE_RELEASE). Here we send a wakeup signal if
-# it's sleeping or do nothing otherwise, and print a null value in either
-# case.
-step s4_wakeup_s1_setup
-{
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-			      WHERE wait_event_type = 'InjectionPoint' AND
-			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-}
-step s4_wakeup_s1
-{
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-}
-step s4_wakeup_s2
-{
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-}
-step s4_wakeup_define_index_before_set_valid
-{
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-}
-
-session s5
-step s5_wakeup_s1_from_invalidate_catalog_snapshot
-{
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-}
-
-permutation
-	s1_attach_invalidate_catalog_snapshot
-	s4_wakeup_s1_setup
-	s3_start_create_index(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
-	s4_wakeup_define_index_before_set_valid
-	s2_start_upsert(s1_start_upsert)
-	s5_wakeup_s1_from_invalidate_catalog_snapshot
-	s4_wakeup_s2
-	s4_wakeup_s1
diff --git a/src/test/modules/injection_points/specs/index-concurrently-upsert.spec b/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
deleted file mode 100644
index 6e08af74a93..00000000000
--- a/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
+++ /dev/null
@@ -1,123 +0,0 @@
-# This test verifies INSERT ON CONFLICT DO UPDATE behavior concurrent with
-# CREATE INDEX CONCURRENTLY.
-#
-# - s1: UPSERT a tuple
-# - s2: UPSERT the same tuple
-# - s3: CREATE UNIQUE INDEX CONCURRENTLY
-#
-# - s4: Control concurrency using injection points
-
-setup
-{
-	CREATE EXTENSION injection_points;
-	CREATE SCHEMA test;
-	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
-	ALTER TABLE test.tbl SET (parallel_workers=0);
-}
-
-teardown
-{
-	DROP SCHEMA test CASCADE;
-	DROP EXTENSION injection_points;
-}
-
-session s1
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-}
-step s1_attach_invalidate_catalog_snapshot
-{
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-}
-step s1_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s2
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
-}
-step s2_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s3
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('define-index-before-set-valid', 'wait');
-}
-step s3_start_create_index
-{
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
-}
-
-session s4
-# Step s1_attach_invalidate_catalog_snapshot sleeps or not depending on
-# build conditions (CATCACHE_FORCE_RELEASE). Here we send a wakeup signal if
-# it's sleeping or do nothing otherwise, and print a null value in either
-# case.
-step s4_wakeup_s1_setup
-{
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-				  WHERE wait_event_type = 'InjectionPoint' AND
-				  wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-}
-step s4_wakeup_s1
-{
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-}
-step s4_wakeup_s2
-{
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-}
-step s4_wakeup_define_index_before_set_valid
-{
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-}
-
-session s5
-step s5_wakeup_s1_from_invalidate_catalog_snapshot
-{
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-}
-
-permutation
-	s1_attach_invalidate_catalog_snapshot
-	s4_wakeup_s1_setup
-	s3_start_create_index(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
-	s4_wakeup_define_index_before_set_valid
-	s2_start_upsert(s1_start_upsert)
-	s5_wakeup_s1_from_invalidate_catalog_snapshot
-	s4_wakeup_s2
-	s4_wakeup_s1
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec
deleted file mode 100644
index 4bbdda3cf04..00000000000
--- a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec
+++ /dev/null
@@ -1,110 +0,0 @@
-# Test race conditions involving:
-#
-# - s1: UPSERT a tuple
-# - s2: UPSERT the same tuple
-# - s3: concurrently REINDEX the primary key
-#
-# - s4: operations with injection points
-
-setup
-{
-	CREATE EXTENSION injection_points;
-	CREATE SCHEMA test;
-	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
-	ALTER TABLE test.tbl SET (parallel_workers=0);
-}
-
-teardown
-{
-	DROP SCHEMA test CASCADE;
-	DROP EXTENSION injection_points;
-}
-
-session s1
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-}
-step s1_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
-}
-
-session s2
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
-}
-step s2_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
-}
-
-session s3
-setup
-{
-	SELECT injection_points_set_local();
-}
-step s3_setup_wait_before_set_dead
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-}
-step s3_setup_wait_before_swap
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-}
-step s3_start_reindex
-{
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
-}
-
-session s4
-step s4_wakeup_to_swap
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-}
-step s4_wakeup_s1
-{
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-}
-step s4_wakeup_s2
-{
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-}
-step s4_wakeup_to_set_dead
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-}
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_set_dead
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_s2
-
-permutation
-	s3_setup_wait_before_swap
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_swap
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s2
-	s4_wakeup_s1
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_to_set_dead
-	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
deleted file mode 100644
index c3504b9ef38..00000000000
--- a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
+++ /dev/null
@@ -1,113 +0,0 @@
-# This test verifies INSERT ON CONFLICT DO UPDATE behavior on partitioned
-# tables concurrent with REINDEX CONCURRENTLY.
-#
-# - s1: UPSERT a tuple
-# - s2: UPSERT the same tuple
-# - s3: concurrently REINDEX the primary key index
-#
-# - s4: controls concurrency via injection points
-
-setup
-{
-	CREATE EXTENSION injection_points;
-	CREATE SCHEMA test;
-	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
-	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
-		FOR VALUES FROM (0) TO (10000)
-		WITH (parallel_workers = 0);
-}
-
-teardown
-{
-	DROP SCHEMA test CASCADE;
-	DROP EXTENSION injection_points;
-}
-
-session s1
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-}
-step s1_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s2
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
-}
-step s2_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s3
-setup
-{
-	SELECT injection_points_set_local();
-}
-step s3_setup_wait_before_set_dead
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-}
-step s3_setup_wait_before_swap
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-}
-step s3_start_reindex
-{
-	REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
-}
-
-session s4
-step s4_wakeup_to_swap
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-}
-step s4_wakeup_s1
-{
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-}
-step s4_wakeup_s2
-{
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-}
-step s4_wakeup_to_set_dead
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-}
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_set_dead
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_s2
-
-permutation
-	s3_setup_wait_before_swap
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_swap
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s2
-	s4_wakeup_s1
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_to_set_dead
-	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec
deleted file mode 100644
index 1b043a48ff4..00000000000
--- a/src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec
+++ /dev/null
@@ -1,111 +0,0 @@
-# This test verifies INSERT ON CONFLICT DO UPDATE behavior concurrent with
-# REINDEX CONCURRENTLY.
-#
-# - s1: UPSERT a tuple
-# - s2: UPSERT the same tuple
-# - s3: REINDEX concurrent primary key index
-#
-# - s4: controls concurrency via injection points
-
-setup
-{
-	CREATE EXTENSION injection_points;
-	CREATE SCHEMA test;
-	CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
-	ALTER TABLE test.tbl SET (parallel_workers=0);
-}
-
-teardown
-{
-	DROP SCHEMA test CASCADE;
-	DROP EXTENSION injection_points;
-}
-
-session s1
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-}
-step s1_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s2
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
-}
-step s2_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s3
-setup
-{
-	SELECT injection_points_set_local();
-}
-step s3_setup_wait_before_set_dead
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-}
-step s3_setup_wait_before_swap
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-}
-step s3_start_reindex
-{
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
-}
-
-session s4
-step s4_wakeup_to_swap
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-}
-step s4_wakeup_s1
-{
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-}
-step s4_wakeup_s2
-{
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-}
-step s4_wakeup_to_set_dead
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-}
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_set_dead
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_s2
-
-permutation
-	s3_setup_wait_before_swap
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_swap
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s2
-	s4_wakeup_s1
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_to_set_dead
-	s4_wakeup_s2
diff --git a/src/test/modules/test_misc/Makefile b/src/test/modules/test_misc/Makefile
index 399b9094a38..fedbef071ef 100644
--- a/src/test/modules/test_misc/Makefile
+++ b/src/test/modules/test_misc/Makefile
@@ -5,6 +5,9 @@ TAP_TESTS = 1
 EXTRA_INSTALL=src/test/modules/injection_points \
 	contrib/test_decoding
 
+# The injection points are cluster-wide, so disable installcheck
+NO_INSTALLCHECK = 1
+
 export enable_injection_points
 
 ifdef USE_PGXS
diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build
index f258bf1ccd9..129c4ae587a 100644
--- a/src/test/modules/test_misc/meson.build
+++ b/src/test/modules/test_misc/meson.build
@@ -18,6 +18,9 @@ tests += {
       't/007_catcache_inval.pl',
       't/008_replslot_single_user.pl',
       't/009_log_temp_files.pl',
+      't/010_index_concurrently_upsert.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl b/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
new file mode 100644
index 00000000000..55ea384edb3
--- /dev/null
+++ b/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
@@ -0,0 +1,894 @@
+
+# Copyright (c) 2025, PostgreSQL Global Development Group
+
+# Test INSERT ON CONFLICT DO UPDATE behavior concurrent with
+# CREATE INDEX CONCURRENTLY and REINDEX CONCURRENTLY.
+#
+# These tests verify the fix for "duplicate key value violates unique constraint"
+# errors that occurred when infer_arbiter_indexes() only considered indisvalid
+# indexes, causing different transactions to use different arbiter indexes.
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Test::More;
+
+if ($ENV{enable_injection_points} ne 'yes')
+{
+	plan skip_all => 'Injection points not supported by this build';
+}
+
+# Node initialization
+my $node = PostgreSQL::Test::Cluster->new('node');
+$node->init();
+$node->start;
+
+# Check if the extension injection_points is available
+if (!$node->check_extension('injection_points'))
+{
+	plan skip_all => 'Extension injection_points not installed';
+}
+
+$node->safe_psql('postgres', 'CREATE EXTENSION injection_points;');
+
+# Helper: Wait for a session to hit an injection point.
+# Optional second argument is timeout in seconds.
+# Returns true if found, false if timeout.
+# On timeout, logs diagnostic information about all active queries.
+sub wait_for_injection_point
+{
+	my ($node, $point_name, $timeout) = @_;
+	$timeout //= 120;
+
+	for (my $elapsed = 0; $elapsed < $timeout; $elapsed++)
+	{
+		my $pid = $node->safe_psql('postgres', qq[
+			SELECT pid FROM pg_stat_activity
+			WHERE wait_event_type = 'InjectionPoint'
+			  AND wait_event = '$point_name'
+			LIMIT 1;
+		]);
+		return 1 if $pid ne '';
+		sleep(1);
+	}
+
+	# Timeout - report diagnostic information
+    my $activity = $node->safe_psql('postgres', q[
+        SELECT format('pid=%s, state=%s, wait_event_type=%s, wait_event=%s, backend_xmin=%s, backend_xid=%s, query=%s',
+            pid, state, wait_event_type, wait_event, backend_xmin, backend_xid, left(query, 100))
+        FROM pg_stat_activity
+        ORDER BY pid;
+    ]);
+    diag("wait_for_injection_point timeout waiting for: $point_name\n" .
+         "Current queries in pg_stat_activity:\n$activity");
+
+	return 0;
+}
+
+# Helper: Wait for a specific backend to become idle.
+# Returns true if idle, false if timeout.
+sub wait_for_idle
+{
+	my ($node, $pid, $timeout) = @_;
+	$timeout //= 15;
+
+	for (my $elapsed = 0; $elapsed < $timeout; $elapsed++)
+	{
+		my $state = $node->safe_psql('postgres', qq[
+			SELECT state FROM pg_stat_activity WHERE pid = $pid;
+		]);
+		return 1 if $state eq 'idle';
+		sleep(1);
+	}
+	return 0;
+}
+
+# Helper: Detach and wakeup an injection point
+sub wakeup_injection_point
+{
+	my ($node, $point_name) = @_;
+	$node->safe_psql(
+		'postgres', qq[
+SELECT injection_points_detach('$point_name');
+SELECT injection_points_wakeup('$point_name');
+]);
+}
+
+# Wait for any pending query to complete, capture stderr, and close the session.
+# Returns the stderr output (excluding internal markers).
+sub safe_quit
+{
+	my ($session) = @_;
+
+	# Send a marker and wait for it to ensure any pending query completes
+	my $banner = "safe_quit_marker";
+	my $banner_match = qr/(^|\n)$banner\r?\n/;
+
+	$session->{stdin} .= "\\echo $banner\n\\warn $banner\n";
+
+	pump_until($session->{run}, $session->{timeout},
+		\$session->{stdout}, $banner_match);
+	pump_until($session->{run}, $session->{timeout},
+		\$session->{stderr}, $banner_match);
+
+	# Capture stderr (excluding the banner)
+	my $stderr = $session->{stderr};
+	$stderr =~ s/$banner_match//;
+
+	# Close the session
+	$session->quit;
+
+	return $stderr;
+}
+
+###############################################################################
+# Test 1: REINDEX CONCURRENTLY + UPSERT (wakeup at set-dead phase)
+# Based on reindex-concurrently-upsert.spec
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+# Create sessions with on_error_stop => 0 so psql doesn't exit on SQL errors.
+# This allows us to collect stderr and detect errors after the test completes.
+my $s1 = $node->background_psql('postgres', on_error_stop => 0);
+my $s2 = $node->background_psql('postgres', on_error_stop => 0);
+my $s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+# Setup injection points for each session
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+# s3 starts REINDEX (will block on reindex-relation-concurrently-before-set-dead)
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+# Wait for s3 to hit injection point
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+# s1 starts UPSERT (will block on check-exclusion-or-unique-constraint-no-conflict)
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+# Wait for s1 to hit injection point
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+# Wakeup s3 to continue (reindex-relation-concurrently-before-set-dead)
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+
+# s2 starts UPSERT (will block on exec-insert-before-insert-speculative)
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+# Wait for s2 to hit injection point
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+# Wakeup s1 (check-exclusion-or-unique-constraint-no-conflict)
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+# Wakeup s2 (exec-insert-before-insert-speculative)
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 1 (REINDEX swap): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 1 (REINDEX swap): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 1 (REINDEX swap): session s3 quit successfully');
+
+# Cleanup test 1
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 2: REINDEX CONCURRENTLY + UPSERT (wakeup at swap phase)
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-swap'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-swap');
+
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+is(safe_quit($s1), '', 'Test 2 (REINDEX set-dead): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 2 (REINDEX set-dead): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 2 (REINDEX set-dead): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 2b: REINDEX CONCURRENTLY + UPSERT (permutation 3: s1 wakes before reindex)
+# Different timing: s2 starts, then s1 wakes, then reindex wakes, then s2 wakes
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+# Start s2 BEFORE waking reindex (key difference from permutation 1)
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+# Wake s1 first, then reindex, then s2
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 2b (REINDEX perm3): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 2b (REINDEX perm3): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 2b (REINDEX perm3): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 3: REINDEX + UPSERT ON CONSTRAINT (set-dead phase)
+# Based on reindex-concurrently-upsert-on-constraint.spec
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 3 (ON CONSTRAINT set-dead): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 3 (ON CONSTRAINT set-dead): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 3 (ON CONSTRAINT set-dead): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 4: REINDEX + UPSERT ON CONSTRAINT (swap phase)
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-swap'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-swap');
+
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+is(safe_quit($s1), '', 'Test 4 (ON CONSTRAINT swap): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 4 (ON CONSTRAINT swap): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 4 (ON CONSTRAINT swap): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 4b: REINDEX + UPSERT ON CONSTRAINT (permutation 3: s1 wakes before reindex)
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+# Start s2 BEFORE waking reindex
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+# Wake s1 first, then reindex, then s2
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 4b (ON CONSTRAINT perm3): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 4b (ON CONSTRAINT perm3): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 4b (ON CONSTRAINT perm3): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 5: REINDEX on partitioned table (set-dead phase)
+# Based on reindex-concurrently-upsert-partitioned.spec
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+    FOR VALUES FROM (0) TO (10000)
+    WITH (parallel_workers = 0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 5 (partitioned set-dead): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 5 (partitioned set-dead): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 5 (partitioned set-dead): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 6: REINDEX on partitioned table (swap phase)
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+    FOR VALUES FROM (0) TO (10000)
+    WITH (parallel_workers = 0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-swap'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-swap');
+
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+is(safe_quit($s1), '', 'Test 6 (partitioned swap): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 6 (partitioned swap): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 6 (partitioned swap): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 6b: REINDEX on partitioned table (permutation 3: s1 wakes before reindex)
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+    FOR VALUES FROM (0) TO (10000)
+    WITH (parallel_workers = 0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+# Start s2 BEFORE waking reindex
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+# Wake s1 first, then reindex, then s2
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 6b (partitioned perm3): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 6b (partitioned perm3): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 6b (partitioned perm3): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 7: CREATE INDEX CONCURRENTLY + UPSERT
+# Based on index-concurrently-upsert.spec
+# Uses invalidate-catalog-snapshot-end to test catalog invalidation during UPSERT
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+my $s1_pid = $s1->query_safe('SELECT pg_backend_pid()');
+
+# s1 attaches BOTH injection points - the unique constraint check AND catalog snapshot
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s1->query_until(qr/attaching_injection_point/, q[
+\echo attaching_injection_point
+SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+]);
+# In case of CLOBBER_CACHE_ALWAYS - s1 may hit the injection point during attach.
+# Wait for s1 to become idle (attach completed) or wakeup if stuck on injection point.
+if (!wait_for_idle($node, $s1_pid))
+{
+	ok(wait_for_injection_point($node, 'invalidate-catalog-snapshot-end'),
+		'Test 7: s1 hit injection point during attach (CLOBBER_CACHE_ALWAYS)');
+	$node->safe_psql('postgres', q[
+		SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+	]);
+}
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('define-index-before-set-valid', 'wait');
+]);
+
+# s3: Start CREATE INDEX CONCURRENTLY (blocks on define-index-before-set-valid)
+$s3->query_until(qr/starting_create_index/, q[
+\echo starting_create_index
+CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
+]);
+
+ok(wait_for_injection_point($node, 'define-index-before-set-valid'));
+
+# s1: Start UPSERT (blocks on invalidate-catalog-snapshot-end)
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'invalidate-catalog-snapshot-end'));
+
+# Wakeup s3 (CREATE INDEX continues, triggers catalog invalidation)
+wakeup_injection_point($node, 'define-index-before-set-valid');
+
+# s2: Start UPSERT (blocks on exec-insert-before-insert-speculative)
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'invalidate-catalog-snapshot-end');
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+is(safe_quit($s1), '', 'Test 7 (CREATE INDEX): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 7 (CREATE INDEX): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 7 (CREATE INDEX): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 8: CREATE INDEX CONCURRENTLY on partial index + UPSERT
+# Based on index-concurrently-upsert-predicate.spec
+# Uses invalidate-catalog-snapshot-end to test catalog invalidation during UPSERT
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1_pid = $s1->query_safe('SELECT pg_backend_pid()');
+
+# s1 attaches BOTH injection points - the unique constraint check AND catalog snapshot
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s1->query_until(qr/attaching_injection_point/, q[
+\echo attaching_injection_point
+SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+]);
+# In case of CLOBBER_CACHE_ALWAYS - s1 may hit the injection point during attach.
+# Wait for s1 to become idle (attach completed) or wakeup if stuck on injection point.
+if (!wait_for_idle($node, $s1_pid))
+{
+	ok(wait_for_injection_point($node, 'invalidate-catalog-snapshot-end'),
+		'Test 8: s1 hit injection point during attach (CLOBBER_CACHE_ALWAYS)');
+	$node->safe_psql('postgres', q[
+		SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+	]);
+}
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('define-index-before-set-valid', 'wait');
+]);
+
+# s3: Start CREATE INDEX CONCURRENTLY (blocks on define-index-before-set-valid)
+$s3->query_until(qr/starting_create_index/, q[
+\echo starting_create_index
+CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
+]);
+
+ok(wait_for_injection_point($node, 'define-index-before-set-valid'));
+
+# s1: Start UPSERT (blocks on invalidate-catalog-snapshot-end)
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'invalidate-catalog-snapshot-end'));
+
+# Wakeup s3 (CREATE INDEX continues, triggers catalog invalidation)
+wakeup_injection_point($node, 'define-index-before-set-valid');
+
+# s2: Start UPSERT (blocks on exec-insert-before-insert-speculative)
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'invalidate-catalog-snapshot-end');
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+is(safe_quit($s1), '', 'Test 7 (CREATE INDEX): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 7 (CREATE INDEX): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 7 (CREATE INDEX): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+done_testing();
-- 
2.52.0

From 113f1ad1040c3646f6a990a14f5304db903bfe15 Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Mon, 15 Dec 2025 12:03:04 +0100
Subject: [PATCH v2 1/2] Replace flaky CIC/RI isolation tests with stable TAP
 tests
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The isolation tests for INSERT ON CONFLICT behavior during CREATE INDEX CONCURRENTLY and REINDEX CONCURRENTLY were disabled in 77038d6d0b4 due to persistent CI flakiness.

The isolation tester based solution was struggling to reliably ensure exact the same test output. The tests were commented out pending a complete rewrite.

This commit removes the disabled isolation tests and their spec files, originally added in bc32a12e0db, 2bc7e886fc1 and 90eae926abb and replaces them with a TAP test in test_misc module (010_index_concurrently_upsert.pl) that covers the same scenarios.

These tests verify the fixes from referenced commits, and 81f72115cf1 remain effective, preventing "duplicate key value violates unique constraint" errors when concurrent transactions select different arbiter indexes during index state transitions.

Author: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Reported-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Discussion: https://postgr.es/m/ccssrhafzbp3a3beju3ptyc56a7gbfimj4vwkbokoldofckrc7@bso37rxskjtf
Discussion: https://postgr.es/m/CANtu0ogv+6wqRzPK241jik4U95s1pW3MCZ3rX5ZqbFdUysz7Qw@mail.gmail.com
Discussion: https://postgr.es/m/202512112014.icpomgc37zx4@alvherre.pgsql
---
 src/test/modules/injection_points/Makefile    |   8 -
 .../index-concurrently-upsert-predicate.out   | 123 ---
 .../index-concurrently-upsert-predicate_1.out | 124 ---
 .../expected/index-concurrently-upsert.out    | 123 ---
 .../expected/index-concurrently-upsert_1.out  | 124 ---
 ...ndex-concurrently-upsert-on-constraint.out | 238 -----
 ...eindex-concurrently-upsert-partitioned.out | 238 -----
 .../expected/reindex-concurrently-upsert.out  | 238 -----
 src/test/modules/injection_points/meson.build |   6 -
 .../index-concurrently-upsert-predicate.spec  | 124 ---
 .../specs/index-concurrently-upsert.spec      | 123 ---
 ...dex-concurrently-upsert-on-constraint.spec | 110 ---
 ...index-concurrently-upsert-partitioned.spec | 113 ---
 .../specs/reindex-concurrently-upsert.spec    | 111 ---
 src/test/modules/test_misc/Makefile           |   3 +
 src/test/modules/test_misc/meson.build        |   3 +
 .../t/010_index_concurrently_upsert.pl        | 894 ++++++++++++++++++
 17 files changed, 900 insertions(+), 1803 deletions(-)
 delete mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
 delete mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
 delete mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert.out
 delete mode 100644 src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
 delete mode 100644 src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out
 delete mode 100644 src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
 delete mode 100644 src/test/modules/injection_points/expected/reindex-concurrently-upsert.out
 delete mode 100644 src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
 delete mode 100644 src/test/modules/injection_points/specs/index-concurrently-upsert.spec
 delete mode 100644 src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec
 delete mode 100644 src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
 delete mode 100644 src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec
 create mode 100644 src/test/modules/test_misc/t/010_index_concurrently_upsert.pl

diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index bfdb3f53377..3cb50d13e52 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -16,14 +16,6 @@ ISOLATION = basic \
 	    inplace \
 	    syscache-update-pruned
 
-# Temporarily disabled because of flakiness
-#ISOLATION =+
-#	    index-concurrently-upsert \
-#	    index-concurrently-upsert-predicate \
-#	    reindex-concurrently-upsert \
-#	    reindex-concurrently-upsert-on-constraint \
-#	    reindex-concurrently-upsert-partitioned
-
 # The injection points are cluster-wide, so disable installcheck
 NO_INSTALLCHECK = 1
 
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
deleted file mode 100644
index 77e7d1a7815..00000000000
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate.out
+++ /dev/null
@@ -1,123 +0,0 @@
-Parsed test spec with 5 sessions
-
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: 
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1_setup: 
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-			      WHERE wait_event_type = 'InjectionPoint' AND
-			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-
-case
-----
-    
-(1 row)
-
-step s3_start_create_index: 
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_define_index_before_set_valid: 
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out b/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
deleted file mode 100644
index e72848d6a78..00000000000
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert-predicate_1.out
+++ /dev/null
@@ -1,124 +0,0 @@
-Parsed test spec with 5 sessions
-
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: 
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
- <waiting ...>
-step s4_wakeup_s1_setup: 
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-			      WHERE wait_event_type = 'InjectionPoint' AND
-			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-
-case
-----
-    
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: <... completed>
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_create_index: 
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_define_index_before_set_valid: 
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert.out b/src/test/modules/injection_points/expected/index-concurrently-upsert.out
deleted file mode 100644
index a2ef122625c..00000000000
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert.out
+++ /dev/null
@@ -1,123 +0,0 @@
-Parsed test spec with 5 sessions
-
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: 
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1_setup: 
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-				  WHERE wait_event_type = 'InjectionPoint' AND
-				  wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-
-case
-----
-    
-(1 row)
-
-step s3_start_create_index: 
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_define_index_before_set_valid: 
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out b/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
deleted file mode 100644
index ee3b6641b90..00000000000
--- a/src/test/modules/injection_points/expected/index-concurrently-upsert_1.out
+++ /dev/null
@@ -1,124 +0,0 @@
-Parsed test spec with 5 sessions
-
-starting permutation: s1_attach_invalidate_catalog_snapshot s4_wakeup_s1_setup s3_start_create_index s1_start_upsert s4_wakeup_define_index_before_set_valid s2_start_upsert s5_wakeup_s1_from_invalidate_catalog_snapshot s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: 
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
- <waiting ...>
-step s4_wakeup_s1_setup: 
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-				  WHERE wait_event_type = 'InjectionPoint' AND
-				  wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-
-case
-----
-    
-(1 row)
-
-step s1_attach_invalidate_catalog_snapshot: <... completed>
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_create_index: 
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_define_index_before_set_valid: 
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s5_wakeup_s1_from_invalidate_catalog_snapshot: 
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_create_index: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out b/src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out
deleted file mode 100644
index c1ac1f77c61..00000000000
--- a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-on-constraint.out
+++ /dev/null
@@ -1,238 +0,0 @@
-Parsed test spec with 4 sessions
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_swap: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_swap: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out b/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
deleted file mode 100644
index 4c79a43d986..00000000000
--- a/src/test/modules/injection_points/expected/reindex-concurrently-upsert-partitioned.out
+++ /dev/null
@@ -1,238 +0,0 @@
-Parsed test spec with 4 sessions
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_swap: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_swap: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/expected/reindex-concurrently-upsert.out b/src/test/modules/injection_points/expected/reindex-concurrently-upsert.out
deleted file mode 100644
index c9cc9989d02..00000000000
--- a/src/test/modules/injection_points/expected/reindex-concurrently-upsert.out
+++ /dev/null
@@ -1,238 +0,0 @@
-Parsed test spec with 4 sessions
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s4_wakeup_to_set_dead s2_start_upsert s4_wakeup_s1 s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_swap s3_start_reindex s1_start_upsert s4_wakeup_to_swap s2_start_upsert s4_wakeup_s2 s4_wakeup_s1
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_swap: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_to_swap: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
-
-starting permutation: s3_setup_wait_before_set_dead s3_start_reindex s1_start_upsert s2_start_upsert s4_wakeup_s1 s4_wakeup_to_set_dead s4_wakeup_s2
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-injection_points_set_local
---------------------------
-                          
-(1 row)
-
-step s3_setup_wait_before_set_dead: 
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-
-injection_points_attach
------------------------
-                       
-(1 row)
-
-step s3_start_reindex: 
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
- <waiting ...>
-step s1_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s2_start_upsert: 
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
- <waiting ...>
-step s4_wakeup_s1: 
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s1_start_upsert: <... completed>
-step s4_wakeup_to_set_dead: 
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s4_wakeup_s2: 
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-
-injection_points_detach
------------------------
-                       
-(1 row)
-
-injection_points_wakeup
------------------------
-                       
-(1 row)
-
-step s2_start_upsert: <... completed>
-step s3_start_reindex: <... completed>
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index 493e11053dc..2c6cf54a33e 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -46,12 +46,6 @@ tests += {
       'basic',
       'inplace',
       'syscache-update-pruned',
-      # temporarily disabled because of flakiness
-      # 'index-concurrently-upsert',
-      # 'index-concurrently-upsert-predicate',
-      # 'reindex-concurrently-upsert',
-      # 'reindex-concurrently-upsert-on-constraint',
-      # 'reindex-concurrently-upsert-partitioned',
     ],
     'runningcheck': false, # see syscache-update-pruned
     # Some tests wait for all snapshots, so avoid parallel execution
diff --git a/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec b/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
deleted file mode 100644
index d9b8d27fd1f..00000000000
--- a/src/test/modules/injection_points/specs/index-concurrently-upsert-predicate.spec
+++ /dev/null
@@ -1,124 +0,0 @@
-# This test verifies INSERT ON CONFLICT DO UPDATE behavior concurrent with
-# CREATE INDEX CONCURRENTLY a partial index.
-#
-# - s1: UPSERT a tuple
-# - s2: UPSERT the same tuple
-# - s3: CREATE UNIQUE INDEX CONCURRENTLY (with a predicate)
-#
-# - s4 and s5: control concurrency via injection points
-
-setup
-{
-	CREATE EXTENSION injection_points;
-	CREATE SCHEMA test;
-	CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
-	CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
-	ALTER TABLE test.tbl SET (parallel_workers=0);
-}
-
-teardown
-{
-	DROP SCHEMA test CASCADE;
-	DROP EXTENSION injection_points;
-}
-
-session s1
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-}
-step s1_attach_invalidate_catalog_snapshot
-{
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-}
-step s1_start_upsert
-{
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
-}
-
-session s2
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
-}
-step s2_start_upsert
-{
-	INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
-}
-
-session s3
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('define-index-before-set-valid', 'wait');
-}
-step s3_start_create_index
-{
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
-}
-
-session s4
-# Step s1_attach_invalidate_catalog_snapshot sleeps or not depending on
-# build conditions (CATCACHE_FORCE_RELEASE). Here we send a wakeup signal if
-# it's sleeping or do nothing otherwise, and print a null value in either
-# case.
-step s4_wakeup_s1_setup
-{
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-			      WHERE wait_event_type = 'InjectionPoint' AND
-			      wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-}
-step s4_wakeup_s1
-{
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-}
-step s4_wakeup_s2
-{
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-}
-step s4_wakeup_define_index_before_set_valid
-{
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-}
-
-session s5
-step s5_wakeup_s1_from_invalidate_catalog_snapshot
-{
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-}
-
-permutation
-	s1_attach_invalidate_catalog_snapshot
-	s4_wakeup_s1_setup
-	s3_start_create_index(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
-	s4_wakeup_define_index_before_set_valid
-	s2_start_upsert(s1_start_upsert)
-	s5_wakeup_s1_from_invalidate_catalog_snapshot
-	s4_wakeup_s2
-	s4_wakeup_s1
diff --git a/src/test/modules/injection_points/specs/index-concurrently-upsert.spec b/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
deleted file mode 100644
index 6e08af74a93..00000000000
--- a/src/test/modules/injection_points/specs/index-concurrently-upsert.spec
+++ /dev/null
@@ -1,123 +0,0 @@
-# This test verifies INSERT ON CONFLICT DO UPDATE behavior concurrent with
-# CREATE INDEX CONCURRENTLY.
-#
-# - s1: UPSERT a tuple
-# - s2: UPSERT the same tuple
-# - s3: CREATE UNIQUE INDEX CONCURRENTLY
-#
-# - s4: Control concurrency using injection points
-
-setup
-{
-	CREATE EXTENSION injection_points;
-	CREATE SCHEMA test;
-	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
-	ALTER TABLE test.tbl SET (parallel_workers=0);
-}
-
-teardown
-{
-	DROP SCHEMA test CASCADE;
-	DROP EXTENSION injection_points;
-}
-
-session s1
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-}
-step s1_attach_invalidate_catalog_snapshot
-{
-	SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-}
-step s1_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s2
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
-}
-step s2_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s3
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('define-index-before-set-valid', 'wait');
-}
-step s3_start_create_index
-{
-	CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
-}
-
-session s4
-# Step s1_attach_invalidate_catalog_snapshot sleeps or not depending on
-# build conditions (CATCACHE_FORCE_RELEASE). Here we send a wakeup signal if
-# it's sleeping or do nothing otherwise, and print a null value in either
-# case.
-step s4_wakeup_s1_setup
-{
-	SELECT CASE WHEN
-			(SELECT pid FROM pg_stat_activity
-				  WHERE wait_event_type = 'InjectionPoint' AND
-				  wait_event = 'invalidate-catalog-snapshot-end') IS NOT NULL
-			THEN injection_points_wakeup('invalidate-catalog-snapshot-end')
-		END;
-}
-step s4_wakeup_s1
-{
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-}
-step s4_wakeup_s2
-{
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-}
-step s4_wakeup_define_index_before_set_valid
-{
-	SELECT injection_points_detach('define-index-before-set-valid');
-	SELECT injection_points_wakeup('define-index-before-set-valid');
-}
-
-session s5
-step s5_wakeup_s1_from_invalidate_catalog_snapshot
-{
-	DO $$
-		DECLARE
-			v_waiting_pid INTEGER;
-		BEGIN
-		LOOP
-			SELECT pid INTO v_waiting_pid
-			  FROM pg_stat_activity
-			 WHERE wait_event_type = 'InjectionPoint'
-				   AND wait_event = 'invalidate-catalog-snapshot-end'
-			 LIMIT 1;
-			EXIT WHEN v_waiting_pid IS NOT NULL;
-			PERFORM pg_sleep(100);
-		END LOOP;
-		END
-	$$;
-
-	SELECT injection_points_detach('invalidate-catalog-snapshot-end');
-	SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
-}
-
-permutation
-	s1_attach_invalidate_catalog_snapshot
-	s4_wakeup_s1_setup
-	s3_start_create_index(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert
-	s4_wakeup_define_index_before_set_valid
-	s2_start_upsert(s1_start_upsert)
-	s5_wakeup_s1_from_invalidate_catalog_snapshot
-	s4_wakeup_s2
-	s4_wakeup_s1
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec
deleted file mode 100644
index 4bbdda3cf04..00000000000
--- a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-on-constraint.spec
+++ /dev/null
@@ -1,110 +0,0 @@
-# Test race conditions involving:
-#
-# - s1: UPSERT a tuple
-# - s2: UPSERT the same tuple
-# - s3: concurrently REINDEX the primary key
-#
-# - s4: operations with injection points
-
-setup
-{
-	CREATE EXTENSION injection_points;
-	CREATE SCHEMA test;
-	CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
-	ALTER TABLE test.tbl SET (parallel_workers=0);
-}
-
-teardown
-{
-	DROP SCHEMA test CASCADE;
-	DROP EXTENSION injection_points;
-}
-
-session s1
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-}
-step s1_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
-}
-
-session s2
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
-}
-step s2_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
-}
-
-session s3
-setup
-{
-	SELECT injection_points_set_local();
-}
-step s3_setup_wait_before_set_dead
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-}
-step s3_setup_wait_before_swap
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-}
-step s3_start_reindex
-{
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
-}
-
-session s4
-step s4_wakeup_to_swap
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-}
-step s4_wakeup_s1
-{
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-}
-step s4_wakeup_s2
-{
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-}
-step s4_wakeup_to_set_dead
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-}
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_set_dead
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_s2
-
-permutation
-	s3_setup_wait_before_swap
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_swap
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s2
-	s4_wakeup_s1
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_to_set_dead
-	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
deleted file mode 100644
index c3504b9ef38..00000000000
--- a/src/test/modules/injection_points/specs/reindex-concurrently-upsert-partitioned.spec
+++ /dev/null
@@ -1,113 +0,0 @@
-# This test verifies INSERT ON CONFLICT DO UPDATE behavior on partitioned
-# tables concurrent with REINDEX CONCURRENTLY.
-#
-# - s1: UPSERT a tuple
-# - s2: UPSERT the same tuple
-# - s3: concurrently REINDEX the primary key index
-#
-# - s4: controls concurrency via injection points
-
-setup
-{
-	CREATE EXTENSION injection_points;
-	CREATE SCHEMA test;
-	CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
-	CREATE TABLE test.tbl_partition PARTITION OF test.tbl
-		FOR VALUES FROM (0) TO (10000)
-		WITH (parallel_workers = 0);
-}
-
-teardown
-{
-	DROP SCHEMA test CASCADE;
-	DROP EXTENSION injection_points;
-}
-
-session s1
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-}
-step s1_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s2
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
-}
-step s2_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s3
-setup
-{
-	SELECT injection_points_set_local();
-}
-step s3_setup_wait_before_set_dead
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-}
-step s3_setup_wait_before_swap
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-}
-step s3_start_reindex
-{
-	REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
-}
-
-session s4
-step s4_wakeup_to_swap
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-}
-step s4_wakeup_s1
-{
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-}
-step s4_wakeup_s2
-{
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-}
-step s4_wakeup_to_set_dead
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-}
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_set_dead
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_s2
-
-permutation
-	s3_setup_wait_before_swap
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_swap
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s2
-	s4_wakeup_s1
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_to_set_dead
-	s4_wakeup_s2
diff --git a/src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec b/src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec
deleted file mode 100644
index 1b043a48ff4..00000000000
--- a/src/test/modules/injection_points/specs/reindex-concurrently-upsert.spec
+++ /dev/null
@@ -1,111 +0,0 @@
-# This test verifies INSERT ON CONFLICT DO UPDATE behavior concurrent with
-# REINDEX CONCURRENTLY.
-#
-# - s1: UPSERT a tuple
-# - s2: UPSERT the same tuple
-# - s3: REINDEX concurrent primary key index
-#
-# - s4: controls concurrency via injection points
-
-setup
-{
-	CREATE EXTENSION injection_points;
-	CREATE SCHEMA test;
-	CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
-	ALTER TABLE test.tbl SET (parallel_workers=0);
-}
-
-teardown
-{
-	DROP SCHEMA test CASCADE;
-	DROP EXTENSION injection_points;
-}
-
-session s1
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
-}
-step s1_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s2
-setup
-{
-	SELECT injection_points_set_local();
-	SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
-}
-step s2_start_upsert
-{
-	INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-}
-
-session s3
-setup
-{
-	SELECT injection_points_set_local();
-}
-step s3_setup_wait_before_set_dead
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
-}
-step s3_setup_wait_before_swap
-{
-	SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
-}
-step s3_start_reindex
-{
-	REINDEX INDEX CONCURRENTLY test.tbl_pkey;
-}
-
-session s4
-step s4_wakeup_to_swap
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-swap');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-swap');
-}
-step s4_wakeup_s1
-{
-	SELECT injection_points_detach('check-exclusion-or-unique-constraint-no-conflict');
-	SELECT injection_points_wakeup('check-exclusion-or-unique-constraint-no-conflict');
-}
-step s4_wakeup_s2
-{
-	SELECT injection_points_detach('exec-insert-before-insert-speculative');
-	SELECT injection_points_wakeup('exec-insert-before-insert-speculative');
-}
-step s4_wakeup_to_set_dead
-{
-	SELECT injection_points_detach('reindex-relation-concurrently-before-set-dead');
-	SELECT injection_points_wakeup('reindex-relation-concurrently-before-set-dead');
-}
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_set_dead
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_s2
-
-permutation
-	s3_setup_wait_before_swap
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s4_wakeup_to_swap
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s2
-	s4_wakeup_s1
-
-permutation
-	s3_setup_wait_before_set_dead
-	s3_start_reindex(s1_start_upsert, s2_start_upsert)
-	s1_start_upsert(s4_wakeup_s2)
-	s2_start_upsert(s1_start_upsert)
-	s4_wakeup_s1
-	s4_wakeup_to_set_dead
-	s4_wakeup_s2
diff --git a/src/test/modules/test_misc/Makefile b/src/test/modules/test_misc/Makefile
index 399b9094a38..fedbef071ef 100644
--- a/src/test/modules/test_misc/Makefile
+++ b/src/test/modules/test_misc/Makefile
@@ -5,6 +5,9 @@ TAP_TESTS = 1
 EXTRA_INSTALL=src/test/modules/injection_points \
 	contrib/test_decoding
 
+# The injection points are cluster-wide, so disable installcheck
+NO_INSTALLCHECK = 1
+
 export enable_injection_points
 
 ifdef USE_PGXS
diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build
index f258bf1ccd9..129c4ae587a 100644
--- a/src/test/modules/test_misc/meson.build
+++ b/src/test/modules/test_misc/meson.build
@@ -18,6 +18,9 @@ tests += {
       't/007_catcache_inval.pl',
       't/008_replslot_single_user.pl',
       't/009_log_temp_files.pl',
+      't/010_index_concurrently_upsert.pl',
     ],
+    # The injection points are cluster-wide, so disable installcheck
+    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl b/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
new file mode 100644
index 00000000000..e3feb6f2861
--- /dev/null
+++ b/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
@@ -0,0 +1,894 @@
+
+# Copyright (c) 2025, PostgreSQL Global Development Group
+
+# Test INSERT ON CONFLICT DO UPDATE behavior concurrent with
+# CREATE INDEX CONCURRENTLY and REINDEX CONCURRENTLY.
+#
+# These tests verify the fix for "duplicate key value violates unique constraint"
+# errors that occurred when infer_arbiter_indexes() only considered indisvalid
+# indexes, causing different transactions to use different arbiter indexes.
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Test::More;
+
+if ($ENV{enable_injection_points} ne 'yes')
+{
+	plan skip_all => 'Injection points not supported by this build';
+}
+
+# Node initialization
+my $node = PostgreSQL::Test::Cluster->new('node');
+$node->init();
+$node->start;
+
+# Check if the extension injection_points is available
+if (!$node->check_extension('injection_points'))
+{
+	plan skip_all => 'Extension injection_points not installed';
+}
+
+$node->safe_psql('postgres', 'CREATE EXTENSION injection_points;');
+
+# Helper: Wait for a session to hit an injection point.
+# Optional second argument is timeout in seconds.
+# Returns true if found, false if timeout.
+# On timeout, logs diagnostic information about all active queries.
+sub wait_for_injection_point
+{
+	my ($node, $point_name, $timeout) = @_;
+	$timeout //= 120;
+
+	for (my $elapsed = 0; $elapsed < $timeout; $elapsed++)
+	{
+		my $pid = $node->safe_psql('postgres', qq[
+			SELECT pid FROM pg_stat_activity
+			WHERE wait_event_type = 'InjectionPoint'
+			  AND wait_event = '$point_name'
+			LIMIT 1;
+		]);
+		return 1 if $pid ne '';
+		sleep(1);
+	}
+
+	# Timeout - report diagnostic information
+	my $activity = $node->safe_psql('postgres', q[
+		SELECT format('pid=%s, state=%s, wait_event_type=%s, wait_event=%s, backend_xmin=%s, backend_xid=%s, query=%s',
+			pid, state, wait_event_type, wait_event, backend_xmin, backend_xid, left(query, 100))
+		FROM pg_stat_activity
+		ORDER BY pid;
+	]);
+	diag("wait_for_injection_point timeout waiting for: $point_name\n" .
+		"Current queries in pg_stat_activity:\n$activity");
+
+	return 0;
+}
+
+# Helper: Wait for a specific backend to become idle.
+# Returns true if idle, false if timeout.
+sub wait_for_idle
+{
+	my ($node, $pid, $timeout) = @_;
+	$timeout //= 15;
+
+	for (my $elapsed = 0; $elapsed < $timeout; $elapsed++)
+	{
+		my $state = $node->safe_psql('postgres', qq[
+			SELECT state FROM pg_stat_activity WHERE pid = $pid;
+		]);
+		return 1 if $state eq 'idle';
+		sleep(1);
+	}
+	return 0;
+}
+
+# Helper: Detach and wakeup an injection point
+sub wakeup_injection_point
+{
+	my ($node, $point_name) = @_;
+	$node->safe_psql(
+		'postgres', qq[
+SELECT injection_points_detach('$point_name');
+SELECT injection_points_wakeup('$point_name');
+]);
+}
+
+# Wait for any pending query to complete, capture stderr, and close the session.
+# Returns the stderr output (excluding internal markers).
+sub safe_quit
+{
+	my ($session) = @_;
+
+	# Send a marker and wait for it to ensure any pending query completes
+	my $banner = "safe_quit_marker";
+	my $banner_match = qr/(^|\n)$banner\r?\n/;
+
+	$session->{stdin} .= "\\echo $banner\n\\warn $banner\n";
+
+	pump_until($session->{run}, $session->{timeout},
+		\$session->{stdout}, $banner_match);
+	pump_until($session->{run}, $session->{timeout},
+		\$session->{stderr}, $banner_match);
+
+	# Capture stderr (excluding the banner)
+	my $stderr = $session->{stderr};
+	$stderr =~ s/$banner_match//;
+
+	# Close the session
+	$session->quit;
+
+	return $stderr;
+}
+
+###############################################################################
+# Test 1: REINDEX CONCURRENTLY + UPSERT (wakeup at set-dead phase)
+# Based on reindex-concurrently-upsert.spec
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+# Create sessions with on_error_stop => 0 so psql doesn't exit on SQL errors.
+# This allows us to collect stderr and detect errors after the test completes.
+my $s1 = $node->background_psql('postgres', on_error_stop => 0);
+my $s2 = $node->background_psql('postgres', on_error_stop => 0);
+my $s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+# Setup injection points for each session
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+# s3 starts REINDEX (will block on reindex-relation-concurrently-before-set-dead)
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+# Wait for s3 to hit injection point
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+# s1 starts UPSERT (will block on check-exclusion-or-unique-constraint-no-conflict)
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+# Wait for s1 to hit injection point
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+# Wakeup s3 to continue (reindex-relation-concurrently-before-set-dead)
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+
+# s2 starts UPSERT (will block on exec-insert-before-insert-speculative)
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+# Wait for s2 to hit injection point
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+# Wakeup s1 (check-exclusion-or-unique-constraint-no-conflict)
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+# Wakeup s2 (exec-insert-before-insert-speculative)
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 1 (REINDEX set-dead): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 1 (REINDEX set-dead): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 1 (REINDEX set-dead): session s3 quit successfully');
+
+# Cleanup test 1
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 2: REINDEX CONCURRENTLY + UPSERT (wakeup at swap phase)
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-swap'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-swap');
+
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+is(safe_quit($s1), '', 'Test 2 (REINDEX swap): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 2 (REINDEX swap): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 2 (REINDEX swap): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 2b: REINDEX CONCURRENTLY + UPSERT (permutation 3: s1 wakes before reindex)
+# Different timing: s2 starts, then s1 wakes, then reindex wakes, then s2 wakes
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+# Start s2 BEFORE waking reindex (key difference from permutation 1)
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+# Wake s1 first, then reindex, then s2
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 2b (REINDEX perm3): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 2b (REINDEX perm3): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 2b (REINDEX perm3): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 3: REINDEX + UPSERT ON CONSTRAINT (set-dead phase)
+# Based on reindex-concurrently-upsert-on-constraint.spec
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 3 (ON CONSTRAINT set-dead): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 3 (ON CONSTRAINT set-dead): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 3 (ON CONSTRAINT set-dead): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 4: REINDEX + UPSERT ON CONSTRAINT (swap phase)
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-swap'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-swap');
+
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+is(safe_quit($s1), '', 'Test 4 (ON CONSTRAINT swap): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 4 (ON CONSTRAINT swap): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 4 (ON CONSTRAINT swap): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 4b: REINDEX + UPSERT ON CONSTRAINT (permutation 3: s1 wakes before reindex)
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl (i int PRIMARY KEY, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+# Start s2 BEFORE waking reindex
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT ON CONSTRAINT tbl_pkey DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+# Wake s1 first, then reindex, then s2
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 4b (ON CONSTRAINT perm3): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 4b (ON CONSTRAINT perm3): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 4b (ON CONSTRAINT perm3): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 5: REINDEX on partitioned table (set-dead phase)
+# Based on reindex-concurrently-upsert-partitioned.spec
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+    FOR VALUES FROM (0) TO (10000)
+    WITH (parallel_workers = 0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 5 (partitioned set-dead): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 5 (partitioned set-dead): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 5 (partitioned set-dead): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 6: REINDEX on partitioned table (swap phase)
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+    FOR VALUES FROM (0) TO (10000)
+    WITH (parallel_workers = 0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-swap'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-swap');
+
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+is(safe_quit($s1), '', 'Test 6 (partitioned swap): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 6 (partitioned swap): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 6 (partitioned swap): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 6b: REINDEX on partitioned table (permutation 3: s1 wakes before reindex)
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE TABLE test.tbl(i int primary key, updated_at timestamp) PARTITION BY RANGE (i);
+CREATE TABLE test.tbl_partition PARTITION OF test.tbl
+    FOR VALUES FROM (0) TO (10000)
+    WITH (parallel_workers = 0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
+]);
+
+$s3->query_until(qr/starting_reindex/, q[
+\echo starting_reindex
+REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
+]);
+
+ok(wait_for_injection_point($node, 'reindex-relation-concurrently-before-set-dead'));
+
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+# Start s2 BEFORE waking reindex
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+# Wake s1 first, then reindex, then s2
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+wakeup_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+is(safe_quit($s1), '', 'Test 6b (partitioned perm3): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 6b (partitioned perm3): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 6b (partitioned perm3): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 7: CREATE INDEX CONCURRENTLY + UPSERT
+# Based on index-concurrently-upsert.spec
+# Uses invalidate-catalog-snapshot-end to test catalog invalidation during UPSERT
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl(i int primary key, updated_at timestamp);
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+my $s1_pid = $s1->query_safe('SELECT pg_backend_pid()');
+
+# s1 attaches BOTH injection points - the unique constraint check AND catalog snapshot
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s1->query_until(qr/attaching_injection_point/, q[
+\echo attaching_injection_point
+SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+]);
+# In case of CLOBBER_CACHE_ALWAYS - s1 may hit the injection point during attach.
+# Wait for s1 to become idle (attach completed) or wakeup if stuck on injection point.
+if (!wait_for_idle($node, $s1_pid))
+{
+	ok(wait_for_injection_point($node, 'invalidate-catalog-snapshot-end'),
+		'Test 7: s1 hit injection point during attach (CLOBBER_CACHE_ALWAYS)');
+	$node->safe_psql('postgres', q[
+		SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+	]);
+}
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('define-index-before-set-valid', 'wait');
+]);
+
+# s3: Start CREATE INDEX CONCURRENTLY (blocks on define-index-before-set-valid)
+$s3->query_until(qr/starting_create_index/, q[
+\echo starting_create_index
+CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tbl(i);
+]);
+
+ok(wait_for_injection_point($node, 'define-index-before-set-valid'));
+
+# s1: Start UPSERT (blocks on invalidate-catalog-snapshot-end)
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'invalidate-catalog-snapshot-end'));
+
+# Wakeup s3 (CREATE INDEX continues, triggers catalog invalidation)
+wakeup_injection_point($node, 'define-index-before-set-valid');
+
+# s2: Start UPSERT (blocks on exec-insert-before-insert-speculative)
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'invalidate-catalog-snapshot-end');
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+is(safe_quit($s1), '', 'Test 7 (CREATE INDEX): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 7 (CREATE INDEX): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 7 (CREATE INDEX): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+###############################################################################
+# Test 8: CREATE INDEX CONCURRENTLY on partial index + UPSERT
+# Based on index-concurrently-upsert-predicate.spec
+# Uses invalidate-catalog-snapshot-end to test catalog invalidation during UPSERT
+###############################################################################
+
+$node->safe_psql(
+	'postgres', q[
+CREATE SCHEMA test;
+CREATE UNLOGGED TABLE test.tbl(i int, updated_at timestamp);
+CREATE UNIQUE INDEX tbl_pkey_special ON test.tbl(abs(i)) WHERE i < 1000;
+ALTER TABLE test.tbl SET (parallel_workers=0);
+]);
+
+$s1 = $node->background_psql('postgres', on_error_stop => 0);
+$s2 = $node->background_psql('postgres', on_error_stop => 0);
+$s3 = $node->background_psql('postgres', on_error_stop => 0);
+
+$s1_pid = $s1->query_safe('SELECT pg_backend_pid()');
+
+# s1 attaches BOTH injection points - the unique constraint check AND catalog snapshot
+$s1->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
+]);
+
+$s1->query_until(qr/attaching_injection_point/, q[
+\echo attaching_injection_point
+SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
+]);
+# In case of CLOBBER_CACHE_ALWAYS - s1 may hit the injection point during attach.
+# Wait for s1 to become idle (attach completed) or wakeup if stuck on injection point.
+if (!wait_for_idle($node, $s1_pid))
+{
+	ok(wait_for_injection_point($node, 'invalidate-catalog-snapshot-end'),
+		'Test 8: s1 hit injection point during attach (CLOBBER_CACHE_ALWAYS)');
+	$node->safe_psql('postgres', q[
+		SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
+	]);
+}
+
+$s2->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
+]);
+
+$s3->query_safe(q[
+SELECT injection_points_set_local();
+SELECT injection_points_attach('define-index-before-set-valid', 'wait');
+]);
+
+# s3: Start CREATE INDEX CONCURRENTLY (blocks on define-index-before-set-valid)
+$s3->query_until(qr/starting_create_index/, q[
+\echo starting_create_index
+CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tbl(abs(i)) WHERE i < 10000;
+]);
+
+ok(wait_for_injection_point($node, 'define-index-before-set-valid'));
+
+# s1: Start UPSERT (blocks on invalidate-catalog-snapshot-end)
+$s1->query_until(qr/starting_upsert_s1/, q[
+\echo starting_upsert_s1
+INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'invalidate-catalog-snapshot-end'));
+
+# Wakeup s3 (CREATE INDEX continues, triggers catalog invalidation)
+wakeup_injection_point($node, 'define-index-before-set-valid');
+
+# s2: Start UPSERT (blocks on exec-insert-before-insert-speculative)
+$s2->query_until(qr/starting_upsert_s2/, q[
+\echo starting_upsert_s2
+INSERT INTO test.tbl VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
+]);
+
+ok(wait_for_injection_point($node, 'exec-insert-before-insert-speculative'));
+
+wakeup_injection_point($node, 'invalidate-catalog-snapshot-end');
+
+ok(wait_for_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict'));
+
+wakeup_injection_point($node, 'exec-insert-before-insert-speculative');
+
+wakeup_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
+
+is(safe_quit($s1), '', 'Test 8 (CREATE INDEX predicate): session s1 quit successfully');
+is(safe_quit($s2), '', 'Test 8 (CREATE INDEX predicate): session s2 quit successfully');
+is(safe_quit($s3), '', 'Test 8 (CREATE INDEX predicate): session s3 quit successfully');
+
+$node->safe_psql('postgres', 'DROP SCHEMA test CASCADE;');
+
+done_testing();
-- 
2.52.0

From 8ee39bbf4804eb653b3db5d1527f5f6cceb2d72d Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <nkey@toloka.ai>
Date: Thu, 18 Dec 2025 12:15:03 +0100
Subject: [PATCH v2 2/2] !!DO NOT PUSH IT!!

intentionally breaks PG to ensure the test actually covering possible issues
---
 src/backend/executor/execPartition.c | 2 +-
 src/backend/optimizer/util/plancat.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index e30db12113b..fe18fac371b 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -807,7 +807,7 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
 			 * same set as arbiters during REINDEX CONCURRENTLY, to avoid
 			 * spurious "duplicate key" errors.
 			 */
-			if (unparented_idxs && arbiterIndexes)
+			if (unparented_idxs && arbiterIndexes && false)
 			{
 				foreach_int(unparented_i, unparented_idxs)
 				{
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index bf45c355b77..a888d230411 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -996,7 +996,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 		 * negatives, we require that we include in the set of inferred
 		 * indexes at least one index that is marked valid.
 		 */
-		if (!idxForm->indisready)
+		if (!idxForm->indisvalid)
 			continue;
 
 		/*
@@ -1029,7 +1029,7 @@ infer_arbiter_indexes(PlannerInfo *root)
 			/* Consider this one a match already */
 			results = lappend_oid(results, idxForm->indexrelid);
 			foundValid |= idxForm->indisvalid;
-			continue;
+			break;
 		}
 		else if (indexOidFromConstraint != InvalidOid)
 		{
-- 
2.52.0

From 538a20ec9abab8642e0770cd52a3adeb458c7d42 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 8 Jan 2026 20:25:41 +0300
Subject: [PATCH v1 1/2] Fix wait_for_idle() to properly handle
 CLOBBER_CACHE_ALWAYS builds
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

In commit e1c971945d62, the test 010_index_concurrently_upsert.pl was added with logic to handle CLOBBER_CACHE_ALWAYS builds, where a backend can hit an injection point while attaching it due to catalog cache invalidation. The wait_for_idle() function detects whether the attachment completed or the backend became stuck waiting on an injection point.

However, using the full TAP framework timeout causes the test to wait indefinitely when a backend is stuck, until the test harness terminates it. This prevents the recovery logic from executing.

Fix by reducing the timeout to half the TAP default, and adding early exit when the backend is detected waiting on an injection point. This allows the test to promptly detect stuck backends and wake them up.

Also reduce wait_for_injection_point() timeout to half the TAP default, ensuring time remains for diagnostic output if the test gets stuck.

Author: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Discussion: https://postgr.es/m/CADzfLwWOVyJygX6BFuyuhTKkJ7uw2e8OcVCDnf6iqnOFhMPE%2BA%40mail.gmail.com
---
 .../test_misc/t/010_index_concurrently_upsert.pl | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl b/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
index 5953af11e9e..1f3dcd80886 100644
--- a/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
+++ b/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
@@ -1,5 +1,5 @@
 
-# Copyright (c) 2025, PostgreSQL Global Development Group
+# Copyright (c) 2026, PostgreSQL Global Development Group
 
 # Test INSERT ON CONFLICT DO UPDATE behavior concurrent with
 # CREATE INDEX CONCURRENTLY and REINDEX CONCURRENTLY.
@@ -793,7 +793,7 @@ done_testing();
 sub wait_for_injection_point
 {
 	my ($node, $point_name, $timeout) = @_;
-	$timeout //= $PostgreSQL::Test::Utils::timeout_default;
+	$timeout //= $PostgreSQL::Test::Utils::timeout_default / 2;
 
 	for (my $elapsed = 0; $elapsed < $timeout * 10; $elapsed++)
 	{
@@ -833,19 +833,23 @@ sub ok_injection_point
 }
 
 # Helper: Wait for a specific backend to become idle.
-# Returns true if idle, false if timeout.
+# Returns true if idle, false if waiting for injection point or timeout.
 sub wait_for_idle
 {
 	my ($node, $pid, $timeout) = @_;
-	$timeout //= $PostgreSQL::Test::Utils::timeout_default;
+	$timeout //= $PostgreSQL::Test::Utils::timeout_default / 2;
 
 	for (my $elapsed = 0; $elapsed < $timeout * 10; $elapsed++)
 	{
-		my $state = $node->safe_psql(
+		my $result = $node->safe_psql(
 			'postgres', qq[
-			SELECT state FROM pg_stat_activity WHERE pid = $pid;
+			SELECT state, wait_event_type FROM pg_stat_activity WHERE pid = $pid;
 		]);
+		my ($state, $wait_event_type) = split(/\|/, $result, 2);
+		$state //= '';
+		$wait_event_type //= '';
 		return 1 if $state eq 'idle';
+		return 0 if $wait_event_type eq 'InjectionPoint';
 		sleep(0.1);
 	}
 	return 0;
-- 
2.43.0

From 7f0aa3ae4b6be42b0797f757faedf2d43a02ca72 Mon Sep 17 00:00:00 2001
From: nkey <mihailnikalayeu@gmail.com>
Date: Thu, 8 Jan 2026 21:09:07 +0300
Subject: [PATCH v1 2/2] Allow test_misc TAP tests to run during installcheck
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Commit e1c971945d62 disabled installcheck for the entire test_misc module because injection points are cluster-wide and incompatible with a concurrently running test execution. However, this also prevents other tests in the module (001-009) from running during installcheck.

Instead of disabling the whole module, introduce an 'is_installcheck' environment variable set by both Meson and Make build systems.

Individual tests can check this variable and skip themselves when running under installcheck. The injection point test now skips itself when is_installcheck='yes', while other tests in test_misc continue to run normally.

Author: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Discussion: https://postgr.es/m/CADzfLwWOVyJygX6BFuyuhTKkJ7uw2e8OcVCDnf6iqnOFhMPE%2BA%40mail.gmail.com
---
 meson.build                                                | 6 ++++--
 src/Makefile.global.in                                     | 7 +++++++
 src/test/modules/test_misc/Makefile                        | 3 ---
 src/test/modules/test_misc/meson.build                     | 2 --
 .../modules/test_misc/t/010_index_concurrently_upsert.pl   | 5 +++++
 5 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/meson.build b/meson.build
index 2064d1b0a8d..91d6bed7d46 100644
--- a/meson.build
+++ b/meson.build
@@ -3811,9 +3811,11 @@ endforeach # directories with tests
 # repeat condition so meson realizes version dependency
 add_test_setup('tmp_install',
   is_default: true,
-  exclude_suites: running_suites)
+  exclude_suites: running_suites,
+  env: {'is_installcheck': 'no'})
 add_test_setup('running',
-  exclude_suites: ['setup'] + install_suites)
+  exclude_suites: ['setup'] + install_suites,
+  env: {'is_installcheck': 'yes'})
 
 
 
diff --git a/src/Makefile.global.in b/src/Makefile.global.in
index 371cd7eba2c..2879310a92e 100644
--- a/src/Makefile.global.in
+++ b/src/Makefile.global.in
@@ -469,6 +469,7 @@ cd $(srcdir) && \
    TESTLOGDIR='$(CURDIR)/tmp_check/log' \
    TESTDATADIR='$(CURDIR)/tmp_check' \
    PATH="$(bindir):$(CURDIR):$$PATH" \
+   is_installcheck='yes' \
    PGPORT='6$(DEF_PGPORT)' top_builddir='$(CURDIR)/$(top_builddir)' \
    PG_REGRESS='$(CURDIR)/$(top_builddir)/src/test/regress/pg_regress' \
    share_contrib_dir='$(DESTDIR)$(datadir)/$(datamoduledir)' \
@@ -483,6 +484,7 @@ cd $(srcdir) && \
    TESTLOGDIR='$(CURDIR)/tmp_check/log' \
    TESTDATADIR='$(CURDIR)/tmp_check' \
    PATH="$(bindir):$(CURDIR):$$PATH" \
+   is_installcheck='yes' \
    PGPORT='6$(DEF_PGPORT)' \
    PG_REGRESS='$(top_builddir)/src/test/regress/pg_regress' \
    $(PROVE) $(PG_PROVE_FLAGS) $(PROVE_FLAGS) $(if $(PROVE_TESTS),$(PROVE_TESTS),t/*.pl)
@@ -497,6 +499,7 @@ cd $(srcdir) && \
    TESTLOGDIR='$(CURDIR)/tmp_check/log' \
    TESTDATADIR='$(CURDIR)/tmp_check' \
    $(with_temp_install) \
+   is_installcheck='no' \
    PGPORT='6$(DEF_PGPORT)' top_builddir='$(CURDIR)/$(top_builddir)' \
    PG_REGRESS='$(CURDIR)/$(top_builddir)/src/test/regress/pg_regress' \
    share_contrib_dir='$(abs_top_builddir)/tmp_install$(datadir)/$(datamoduledir)' \
@@ -705,6 +708,7 @@ pg_regress_clean_files = results/ regression.diffs regression.out tmp_check/ tmp
 pg_regress_check = \
     echo "\# +++ regress check in $(subdir) +++" && \
     $(with_temp_install) \
+    is_installcheck='no' \
     $(top_builddir)/src/test/regress/pg_regress \
     --temp-instance=./tmp_check \
     --inputdir=$(srcdir) \
@@ -713,6 +717,7 @@ pg_regress_check = \
     $(pg_regress_locale_flags) $(EXTRA_REGRESS_OPTS)
 pg_regress_installcheck = \
     echo "\# +++ regress install-check in $(subdir) +++" && \
+    is_installcheck='yes' \
     $(top_builddir)/src/test/regress/pg_regress \
     --inputdir=$(srcdir) \
     --bindir='$(bindir)' \
@@ -721,6 +726,7 @@ pg_regress_installcheck = \
 pg_isolation_regress_check = \
     echo "\# +++ isolation check in $(subdir) +++" && \
     $(with_temp_install) \
+    is_installcheck='no' \
     $(top_builddir)/src/test/isolation/pg_isolation_regress \
     --temp-instance=./tmp_check_iso \
     --inputdir=$(srcdir) --outputdir=output_iso \
@@ -729,6 +735,7 @@ pg_isolation_regress_check = \
     $(pg_regress_locale_flags) $(EXTRA_REGRESS_OPTS)
 pg_isolation_regress_installcheck = \
     echo "\# +++ isolation install-check in $(subdir) +++" && \
+    is_installcheck='yes' \
     $(top_builddir)/src/test/isolation/pg_isolation_regress \
     --inputdir=$(srcdir) --outputdir=output_iso \
     --bindir='$(bindir)' \
diff --git a/src/test/modules/test_misc/Makefile b/src/test/modules/test_misc/Makefile
index fedbef071ef..399b9094a38 100644
--- a/src/test/modules/test_misc/Makefile
+++ b/src/test/modules/test_misc/Makefile
@@ -5,9 +5,6 @@ TAP_TESTS = 1
 EXTRA_INSTALL=src/test/modules/injection_points \
 	contrib/test_decoding
 
-# The injection points are cluster-wide, so disable installcheck
-NO_INSTALLCHECK = 1
-
 export enable_injection_points
 
 ifdef USE_PGXS
diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build
index 6e8db1621a7..423f66d8bdc 100644
--- a/src/test/modules/test_misc/meson.build
+++ b/src/test/modules/test_misc/meson.build
@@ -20,7 +20,5 @@ tests += {
       't/009_log_temp_files.pl',
       't/010_index_concurrently_upsert.pl',
     ],
-    # The injection points are cluster-wide, so disable installcheck
-    'runningcheck': false,
   },
 }
diff --git a/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl b/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
index 1f3dcd80886..dbf04c6e345 100644
--- a/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
+++ b/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
@@ -19,6 +19,11 @@ use Test::More;
 plan skip_all => 'Injection points not supported by this build'
   unless $ENV{enable_injection_points} eq 'yes';
 
+plan skip_all => 'The injection points are cluster-wide, so skip for installcheck'
+    unless ($ENV{is_installcheck} eq 'no');
+
+is($ENV{is_installcheck}, 'no', 'should not be executed during installcheck');
+
 # Node initialization
 my $node = PostgreSQL::Test::Cluster->new('node');
 $node->init();
-- 
2.43.0