logical replication does not fire per-column triggers

From e0b5ad061bed9e5a6fcf889124651f6c9fc329cd Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 16 Dec 2019 14:30:42 +0100
Subject: [PATCH v2] Have logical replication subscriber fire column triggers

The logical replication apply worker did not fire per-column update
triggers because the updatedCols bitmap in the RTE was not populated.
This fixes that.
---
 src/backend/replication/logical/worker.c   | 16 +++++++++++
 src/test/subscription/t/003_constraints.pl | 32 +++++++++++++++++++---
 2 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index ced0d191c2..99b2be0835 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -690,6 +690,7 @@ apply_handle_update(StringInfo s)
 	bool		has_oldtup;
 	TupleTableSlot *localslot;
 	TupleTableSlot *remoteslot;
+	RangeTblEntry *target_rte;
 	bool		found;
 	MemoryContext oldctx;
 
@@ -720,6 +721,21 @@ apply_handle_update(StringInfo s)
 								  &estate->es_tupleTable);
 	EvalPlanQualInit(&epqstate, estate, NULL, NIL, -1);
 
+	/*
+	 * Populate updatedCols so that per-column triggers can fire.  This could
+	 * include more columns than were actually changed on the publisher
+	 * because the logical replication protocol doesn't contain that
+	 * information.  But it would for example exclude columns that only exist
+	 * on the subscriber, since we are not touching those.
+	 */
+	target_rte = list_nth(estate->es_range_table, 0);
+	for (int i = 0; i < remoteslot->tts_tupleDescriptor->natts; i++)
+	{
+		if (newtup.changed[i])
+			target_rte->updatedCols = bms_add_member(target_rte->updatedCols,
+													 i + 1 - FirstLowInvalidHeapAttributeNumber);
+	}
+
 	PushActiveSnapshot(GetTransactionSnapshot());
 	ExecOpenIndices(estate->es_result_relation_info, false);
 
diff --git a/src/test/subscription/t/003_constraints.pl b/src/test/subscription/t/003_constraints.pl
index 81547f65fa..34ab11e7fe 100644
--- a/src/test/subscription/t/003_constraints.pl
+++ b/src/test/subscription/t/003_constraints.pl
@@ -3,7 +3,7 @@
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 6;
 
 # Initialize publisher node
 my $node_publisher = get_new_node('publisher');
@@ -81,6 +81,8 @@ BEGIN
         ELSE
             RETURN NULL;
         END IF;
+    ELSIF (TG_OP = 'UPDATE') THEN
+        RETURN NULL;
     ELSE
         RAISE WARNING 'Unknown action';
         RETURN NULL;
@@ -88,7 +90,7 @@ BEGIN
 END;
 \$\$ LANGUAGE plpgsql;
 CREATE TRIGGER filter_basic_dml_trg
-    BEFORE INSERT ON tab_fk_ref
+    BEFORE INSERT OR UPDATE OF bid ON tab_fk_ref
     FOR EACH ROW EXECUTE PROCEDURE filter_basic_dml_fn();
 ALTER TABLE tab_fk_ref ENABLE REPLICA TRIGGER filter_basic_dml_trg;
 });
@@ -99,10 +101,32 @@ BEGIN
 
 $node_publisher->wait_for_catchup('tap_sub');
 
-# The row should be skipped on subscriber
+# The trigger should cause the insert to be skipped on subscriber
+$result = $node_subscriber->safe_psql('postgres',
+	"SELECT count(*), min(bid), max(bid) FROM tab_fk_ref;");
+is($result, qq(2|1|2), 'check replica insert trigger applied on subscriber');
+
+# Update data
+$node_publisher->safe_psql('postgres',
+	"UPDATE tab_fk_ref SET bid = 2 WHERE bid = 1;");
+
+$node_publisher->wait_for_catchup('tap_sub');
+
+# The trigger should cause the update to be skipped on subscriber
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(bid), max(bid) FROM tab_fk_ref;");
-is($result, qq(2|1|2), 'check replica trigger applied on subscriber');
+is($result, qq(2|1|2), 'check replica update column trigger applied on subscriber');
+
+# Update on a column not specified in the trigger, but it will trigger
+# anyway because logical replication ships all columns in an update.
+$node_publisher->safe_psql('postgres',
+	"UPDATE tab_fk_ref SET id = 6 WHERE id = 1;");
+
+$node_publisher->wait_for_catchup('tap_sub');
+
+$result = $node_subscriber->safe_psql('postgres',
+	"SELECT count(*), min(id), max(id) FROM tab_fk_ref;");
+is($result, qq(2|1|2), 'check column trigger applied on even for other column');
 
 $node_subscriber->stop('fast');
 $node_publisher->stop('fast');
-- 
2.24.1