Allow GUC settings in CREATE SUBSCRIPTION CONNECTION to take effect

From 7d458371f8d737357d4d1e6899dd81f916c2d70b Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 19 Nov 2025 08:49:46 +0900
Subject: [PATCH v1] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Previously, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were not used by the publisher's walsender.
For example, in:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

the wal_sender_timeout setting had no effect.
This contrasted with physical replication, where GUCs in primary_conninfo
are applied to the walsender.

This limitation made it difficult to tune logical replication connections
individually, for example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit removes the restriction by changing how logical replication
connections are established so that GUC settings in the CONNECTION string
are properly passed through to and uesd by the walsender. This enables
per-connection configuration for logical replication.
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 43 ++++++++++++++-----
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 239641bfbb6..d880309e2da 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -180,17 +180,6 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 			/* Tell the publisher to translate to our encoding */
 			keys[++i] = "client_encoding";
 			vals[i] = GetDatabaseEncodingName();
-
-			/*
-			 * Force assorted GUC parameters to settings that ensure that the
-			 * publisher will output data values in a form that is unambiguous
-			 * to the subscriber.  (We don't want to modify the subscriber's
-			 * GUC settings, since that might surprise user-defined code
-			 * running in the subscriber, such as triggers.)  This should
-			 * match what pg_dump does.
-			 */
-			keys[++i] = "options";
-			vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
 		}
 		else
 		{
@@ -256,6 +245,38 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 		PQclear(res);
 	}
 
+	/*
+	 * Force assorted GUC parameters to settings that ensure that the
+	 * publisher will output data values in a form that is unambiguous to the
+	 * subscriber.  (We don't want to modify the subscriber's GUC settings,
+	 * since that might surprise user-defined code running in the subscriber,
+	 * such as triggers.)  This should match what pg_dump does.
+	 */
+	if (replication && logical)
+	{
+		const char *params[] =
+		{"datestyle", "intervalstyle", "extra_float_digits", NULL};
+		const char *values[] = {"ISO", "postgres", "3", NULL};
+
+		for (int i = 0; params[i] != NULL; i++)
+		{
+			char		sql[100];
+			PGresult   *res;
+
+			sprintf(sql, "SET %s = %s", params[i], values[i]);
+			res = libpqsrv_exec(conn->streamConn, sql,
+								WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE);
+			if (PQresultStatus(res) != PGRES_COMMAND_OK)
+			{
+				PQclear(res);
+				*err = psprintf(_("could not set %s: %s"),
+								params[i], pchomp(PQerrorMessage(conn->streamConn)));
+				goto bad_connection;
+			}
+			PQclear(res);
+		}
+	}
+
 	conn->logical = logical;
 
 	return conn;
-- 
2.51.2

From 5fc2ab0592d5516b40266df2c786780d49d20b80 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 19 Nov 2025 08:49:46 +0900
Subject: [PATCH v2] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Previously, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were not used by the publisher's walsender.
For example, in:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

the wal_sender_timeout setting had no effect.
This contrasted with physical replication, where GUCs in primary_conninfo
are applied to the walsender.

This limitation made it difficult to tune logical replication connections
individually, for example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit removes the restriction by changing how logical replication
connections are established so that GUC settings in the CONNECTION string
are properly passed through to and uesd by the walsender. This enables
per-connection configuration for logical replication.
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 43 ++++++++++++++-----
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 239641bfbb6..abc74a9230d 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -180,17 +180,6 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 			/* Tell the publisher to translate to our encoding */
 			keys[++i] = "client_encoding";
 			vals[i] = GetDatabaseEncodingName();
-
-			/*
-			 * Force assorted GUC parameters to settings that ensure that the
-			 * publisher will output data values in a form that is unambiguous
-			 * to the subscriber.  (We don't want to modify the subscriber's
-			 * GUC settings, since that might surprise user-defined code
-			 * running in the subscriber, such as triggers.)  This should
-			 * match what pg_dump does.
-			 */
-			keys[++i] = "options";
-			vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
 		}
 		else
 		{
@@ -256,6 +245,38 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 		PQclear(res);
 	}
 
+	/*
+	 * Force assorted GUC parameters to settings that ensure that the
+	 * publisher will output data values in a form that is unambiguous to the
+	 * subscriber.  (We don't want to modify the subscriber's GUC settings,
+	 * since that might surprise user-defined code running in the subscriber,
+	 * such as triggers.)  This should match what pg_dump does.
+	 */
+	if (replication && logical)
+	{
+		const char *params[] =
+		{"datestyle", "intervalstyle", "extra_float_digits", NULL};
+		const char *values[] = {"ISO", "postgres", "3", NULL};
+
+		for (int j = 0; params[j] != NULL; j++)
+		{
+			char		sql[100];
+			PGresult   *res;
+
+			sprintf(sql, "SET %s = %s", params[j], values[j]);
+			res = libpqsrv_exec(conn->streamConn, sql,
+								WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE);
+			if (PQresultStatus(res) != PGRES_COMMAND_OK)
+			{
+				PQclear(res);
+				*err = psprintf(_("could not set %s: %s"),
+								params[j], pchomp(PQerrorMessage(conn->streamConn)));
+				goto bad_connection;
+			}
+			PQclear(res);
+		}
+	}
+
 	conn->logical = logical;
 
 	return conn;
-- 
2.51.2

From 4c5407fd093f1cf77234f4af604f2355d907a61e Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Sat, 22 Nov 2025 22:35:22 +0900
Subject: [PATCH v3] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Previously, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were not used by the publisher's walsender.
For example, in:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

the wal_sender_timeout setting had no effect.
This contrasted with physical replication, where GUCs in primary_conninfo
are applied to the walsender.

This limitation made it difficult to tune logical replication connections
individually, for example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit removes the restriction by changing how logical replication
connections are established so that GUC settings in the CONNECTION string
are properly passed through to and uesd by the walsender. This enables
per-connection configuration for logical replication.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 43 ++++++++++++++-----
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 239641bfbb6..500632b462f 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -180,17 +180,6 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 			/* Tell the publisher to translate to our encoding */
 			keys[++i] = "client_encoding";
 			vals[i] = GetDatabaseEncodingName();
-
-			/*
-			 * Force assorted GUC parameters to settings that ensure that the
-			 * publisher will output data values in a form that is unambiguous
-			 * to the subscriber.  (We don't want to modify the subscriber's
-			 * GUC settings, since that might surprise user-defined code
-			 * running in the subscriber, such as triggers.)  This should
-			 * match what pg_dump does.
-			 */
-			keys[++i] = "options";
-			vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
 		}
 		else
 		{
@@ -256,6 +245,38 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 		PQclear(res);
 	}
 
+	/*
+	 * Force assorted GUC parameters to settings that ensure that the
+	 * publisher will output data values in a form that is unambiguous to the
+	 * subscriber.  (We don't want to modify the subscriber's GUC settings,
+	 * since that might surprise user-defined code running in the subscriber,
+	 * such as triggers.)  This should match what pg_dump does.
+	 */
+	if (replication && logical)
+	{
+		const char *params[] =
+		{"datestyle", "intervalstyle", "extra_float_digits"};
+		const char *values[] = {"ISO", "postgres", "3"};
+
+		for (int j = 0; j < lengthof(params); j++)
+		{
+			char		sql[100];
+			PGresult   *res;
+
+			sprintf(sql, "SET %s = %s", params[j], values[j]);
+			res = libpqsrv_exec(conn->streamConn, sql,
+								WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE);
+			if (PQresultStatus(res) != PGRES_COMMAND_OK)
+			{
+				PQclear(res);
+				*err = psprintf(_("could not set %s: %s"),
+								params[j], pchomp(PQerrorMessage(conn->streamConn)));
+				goto bad_connection;
+			}
+			PQclear(res);
+		}
+	}
+
 	conn->logical = logical;
 
 	return conn;
-- 
2.51.2

From 159e0c886546f3b12ebd48b57d12c68493d5309e Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 26 Nov 2025 23:35:44 +0900
Subject: [PATCH v4] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 43 ++++++++++++++-----
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 568024ec974..1270d162c88 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -170,17 +170,6 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 		/* Tell the publisher to translate to our encoding */
 		keys[++i] = "client_encoding";
 		vals[i] = GetDatabaseEncodingName();
-
-		/*
-		 * Force assorted GUC parameters to settings that ensure that the
-		 * publisher will output data values in a form that is unambiguous to
-		 * the subscriber.  (We don't want to modify the subscriber's GUC
-		 * settings, since that might surprise user-defined code running in
-		 * the subscriber, such as triggers.)  This should match what pg_dump
-		 * does.
-		 */
-		keys[++i] = "options";
-		vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
 	}
 	keys[++i] = NULL;
 	vals[i] = NULL;
@@ -263,6 +252,37 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 		PQclear(res);
 	}
 
+	/*
+	 * Force assorted GUC parameters to settings that ensure that the
+	 * publisher will output data values in a form that is unambiguous to the
+	 * subscriber.  (We don't want to modify the subscriber's GUC settings,
+	 * since that might surprise user-defined code running in the subscriber,
+	 * such as triggers.)  This should match what pg_dump does.
+	 */
+	if (logical)
+	{
+		const char *params[] =
+		{"datestyle", "intervalstyle", "extra_float_digits"};
+		const char *values[] = {"ISO", "postgres", "3"};
+
+		for (int j = 0; j < lengthof(params); j++)
+		{
+			char		sql[100];
+			PGresult   *res;
+
+			sprintf(sql, "SET %s = %s", params[j], values[j]);
+			res = libpqrcv_PQexec(conn->streamConn, sql);
+			if (PQresultStatus(res) != PGRES_COMMAND_OK)
+			{
+				PQclear(res);
+				*err = psprintf(_("could not set %s: %s"),
+								params[j], pchomp(PQerrorMessage(conn->streamConn)));
+				goto bad_connection;
+			}
+			PQclear(res);
+		}
+	}
+
 	conn->logical = logical;
 
 	return conn;
@@ -434,6 +454,7 @@ libpqrcv_identify_system(WalReceiverConn *conn, TimeLineID *primary_tli)
 						"the primary server: %s",
 						pchomp(PQerrorMessage(conn->streamConn)))));
 	}
+
 	/*
 	 * IDENTIFY_SYSTEM returns 3 columns in 9.3 and earlier, and 4 columns in
 	 * 9.4 and onwards.
-- 
2.51.2

From 947cf9d587333219791a257389b95eae01d76237 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 26 Nov 2025 23:35:44 +0900
Subject: [PATCH v4] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 43 ++++++++++++++-----
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 239641bfbb6..500632b462f 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -180,17 +180,6 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 			/* Tell the publisher to translate to our encoding */
 			keys[++i] = "client_encoding";
 			vals[i] = GetDatabaseEncodingName();
-
-			/*
-			 * Force assorted GUC parameters to settings that ensure that the
-			 * publisher will output data values in a form that is unambiguous
-			 * to the subscriber.  (We don't want to modify the subscriber's
-			 * GUC settings, since that might surprise user-defined code
-			 * running in the subscriber, such as triggers.)  This should
-			 * match what pg_dump does.
-			 */
-			keys[++i] = "options";
-			vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
 		}
 		else
 		{
@@ -256,6 +245,38 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 		PQclear(res);
 	}
 
+	/*
+	 * Force assorted GUC parameters to settings that ensure that the
+	 * publisher will output data values in a form that is unambiguous to the
+	 * subscriber.  (We don't want to modify the subscriber's GUC settings,
+	 * since that might surprise user-defined code running in the subscriber,
+	 * such as triggers.)  This should match what pg_dump does.
+	 */
+	if (replication && logical)
+	{
+		const char *params[] =
+		{"datestyle", "intervalstyle", "extra_float_digits"};
+		const char *values[] = {"ISO", "postgres", "3"};
+
+		for (int j = 0; j < lengthof(params); j++)
+		{
+			char		sql[100];
+			PGresult   *res;
+
+			sprintf(sql, "SET %s = %s", params[j], values[j]);
+			res = libpqsrv_exec(conn->streamConn, sql,
+								WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE);
+			if (PQresultStatus(res) != PGRES_COMMAND_OK)
+			{
+				PQclear(res);
+				*err = psprintf(_("could not set %s: %s"),
+								params[j], pchomp(PQerrorMessage(conn->streamConn)));
+				goto bad_connection;
+			}
+			PQclear(res);
+		}
+	}
+
 	conn->logical = logical;
 
 	return conn;
-- 
2.51.2

From 1a1c412e2d320d82d7a6927e5e6550c554a77b23 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 26 Nov 2025 23:35:44 +0900
Subject: [PATCH v4] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 42 ++++++++++++++-----
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 02f12f29219..02f3ee15c87 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -178,17 +178,6 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 			/* Tell the publisher to translate to our encoding */
 			keys[++i] = "client_encoding";
 			vals[i] = GetDatabaseEncodingName();
-
-			/*
-			 * Force assorted GUC parameters to settings that ensure that the
-			 * publisher will output data values in a form that is unambiguous
-			 * to the subscriber.  (We don't want to modify the subscriber's
-			 * GUC settings, since that might surprise user-defined code
-			 * running in the subscriber, such as triggers.)  This should
-			 * match what pg_dump does.
-			 */
-			keys[++i] = "options";
-			vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
 		}
 		else
 		{
@@ -289,6 +278,37 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 		PQclear(res);
 	}
 
+	/*
+	 * Force assorted GUC parameters to settings that ensure that the
+	 * publisher will output data values in a form that is unambiguous to the
+	 * subscriber.  (We don't want to modify the subscriber's GUC settings,
+	 * since that might surprise user-defined code running in the subscriber,
+	 * such as triggers.)  This should match what pg_dump does.
+	 */
+	if (replication && logical)
+	{
+		const char *params[] =
+		{"datestyle", "intervalstyle", "extra_float_digits"};
+		const char *values[] = {"ISO", "postgres", "3"};
+
+		for (int j = 0; j < lengthof(params); j++)
+		{
+			char		sql[100];
+			PGresult   *res;
+
+			sprintf(sql, "SET %s = %s", params[j], values[j]);
+			res = libpqrcv_PQexec(conn->streamConn, sql);
+			if (PQresultStatus(res) != PGRES_COMMAND_OK)
+			{
+				PQclear(res);
+				*err = psprintf(_("could not set %s: %s"),
+								params[j], pchomp(PQerrorMessage(conn->streamConn)));
+				goto bad_connection;
+			}
+			PQclear(res);
+		}
+	}
+
 	conn->logical = logical;
 
 	return conn;
-- 
2.51.2

From 159e0c886546f3b12ebd48b57d12c68493d5309e Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 26 Nov 2025 23:35:44 +0900
Subject: [PATCH v4] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 43 ++++++++++++++-----
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 568024ec974..1270d162c88 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -170,17 +170,6 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 		/* Tell the publisher to translate to our encoding */
 		keys[++i] = "client_encoding";
 		vals[i] = GetDatabaseEncodingName();
-
-		/*
-		 * Force assorted GUC parameters to settings that ensure that the
-		 * publisher will output data values in a form that is unambiguous to
-		 * the subscriber.  (We don't want to modify the subscriber's GUC
-		 * settings, since that might surprise user-defined code running in
-		 * the subscriber, such as triggers.)  This should match what pg_dump
-		 * does.
-		 */
-		keys[++i] = "options";
-		vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
 	}
 	keys[++i] = NULL;
 	vals[i] = NULL;
@@ -263,6 +252,37 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 		PQclear(res);
 	}
 
+	/*
+	 * Force assorted GUC parameters to settings that ensure that the
+	 * publisher will output data values in a form that is unambiguous to the
+	 * subscriber.  (We don't want to modify the subscriber's GUC settings,
+	 * since that might surprise user-defined code running in the subscriber,
+	 * such as triggers.)  This should match what pg_dump does.
+	 */
+	if (logical)
+	{
+		const char *params[] =
+		{"datestyle", "intervalstyle", "extra_float_digits"};
+		const char *values[] = {"ISO", "postgres", "3"};
+
+		for (int j = 0; j < lengthof(params); j++)
+		{
+			char		sql[100];
+			PGresult   *res;
+
+			sprintf(sql, "SET %s = %s", params[j], values[j]);
+			res = libpqrcv_PQexec(conn->streamConn, sql);
+			if (PQresultStatus(res) != PGRES_COMMAND_OK)
+			{
+				PQclear(res);
+				*err = psprintf(_("could not set %s: %s"),
+								params[j], pchomp(PQerrorMessage(conn->streamConn)));
+				goto bad_connection;
+			}
+			PQclear(res);
+		}
+	}
+
 	conn->logical = logical;
 
 	return conn;
@@ -434,6 +454,7 @@ libpqrcv_identify_system(WalReceiverConn *conn, TimeLineID *primary_tli)
 						"the primary server: %s",
 						pchomp(PQerrorMessage(conn->streamConn)))));
 	}
+
 	/*
 	 * IDENTIFY_SYSTEM returns 3 columns in 9.3 and earlier, and 4 columns in
 	 * 9.4 and onwards.
-- 
2.51.2

From 947cf9d587333219791a257389b95eae01d76237 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 26 Nov 2025 23:35:44 +0900
Subject: [PATCH v4] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 43 ++++++++++++++-----
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 239641bfbb6..500632b462f 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -180,17 +180,6 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 			/* Tell the publisher to translate to our encoding */
 			keys[++i] = "client_encoding";
 			vals[i] = GetDatabaseEncodingName();
-
-			/*
-			 * Force assorted GUC parameters to settings that ensure that the
-			 * publisher will output data values in a form that is unambiguous
-			 * to the subscriber.  (We don't want to modify the subscriber's
-			 * GUC settings, since that might surprise user-defined code
-			 * running in the subscriber, such as triggers.)  This should
-			 * match what pg_dump does.
-			 */
-			keys[++i] = "options";
-			vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
 		}
 		else
 		{
@@ -256,6 +245,38 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 		PQclear(res);
 	}
 
+	/*
+	 * Force assorted GUC parameters to settings that ensure that the
+	 * publisher will output data values in a form that is unambiguous to the
+	 * subscriber.  (We don't want to modify the subscriber's GUC settings,
+	 * since that might surprise user-defined code running in the subscriber,
+	 * such as triggers.)  This should match what pg_dump does.
+	 */
+	if (replication && logical)
+	{
+		const char *params[] =
+		{"datestyle", "intervalstyle", "extra_float_digits"};
+		const char *values[] = {"ISO", "postgres", "3"};
+
+		for (int j = 0; j < lengthof(params); j++)
+		{
+			char		sql[100];
+			PGresult   *res;
+
+			sprintf(sql, "SET %s = %s", params[j], values[j]);
+			res = libpqsrv_exec(conn->streamConn, sql,
+								WAIT_EVENT_LIBPQWALRECEIVER_RECEIVE);
+			if (PQresultStatus(res) != PGRES_COMMAND_OK)
+			{
+				PQclear(res);
+				*err = psprintf(_("could not set %s: %s"),
+								params[j], pchomp(PQerrorMessage(conn->streamConn)));
+				goto bad_connection;
+			}
+			PQclear(res);
+		}
+	}
+
 	conn->logical = logical;
 
 	return conn;
-- 
2.51.2

From b8ca4b8637140da82b13f40ae509787bb643fea7 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Thu, 27 Nov 2025 12:36:59 +0900
Subject: [PATCH v4 2/2] Add TAP test for GUC settings passed via CONNECTION in
 logical replication.

This commit adds a TAP test to verify that GUC settings provided in
the CONNECTION string of CREATE/ALTER SUBSCRIPTION are correctly
passed through to and applied by the publisher's walsender.
---
 src/test/subscription/t/001_rep_changes.pl | 28 +++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index 430c1246d14..9d08ae8b641 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -438,17 +438,34 @@ is( $result, qq(11.11|baz|1
 22.22|bar|2),
 	'update works with dropped subscriber column');
 
+# Verify that GUC settings supplied in the CONNECTION string take effect on
+# the publisher's walsender.  We do this by enabling log_disconnections in
+# the CONNECTION string later and checking that the publisher's log contains a
+# disconnection message.
+#
+# First, confirm that no such disconnection message appears before enabling
+# log_disconnections.
+$logfile = slurp_file($node_publisher->logfile, $log_location);
+unlike(
+	$logfile,
+	qr/disconnection: session time:/,
+	'log_disconnections has not been enabled yet');
+
 # check that change of connection string and/or publication list causes
 # restart of subscription workers. We check the state along with
 # application_name to ensure that the walsender is (re)started.
 #
 # Not all of these are registered as tests as we need to poll for a change
 # but the test suite will fail nonetheless when something goes wrong.
+#
+# Enable log_disconnections as the change of connection string,
+# which is also for the above mentioned test of GUC settings passed through
+# CONNECTION.
 my $oldpid = $node_publisher->safe_psql('postgres',
 	"SELECT pid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
 );
 $node_subscriber->safe_psql('postgres',
-	"ALTER SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr sslmode=disable'"
+	"ALTER SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr options=''-c log_disconnections=on'''"
 );
 $node_publisher->poll_query_until('postgres',
 	"SELECT pid != $oldpid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
@@ -552,6 +569,15 @@ $node_publisher->poll_query_until('postgres',
   or die
   "Timed out while waiting for apply to restart after renaming SUBSCRIPTION";
 
+# Check that the expected disconnection message appears,
+# which shows that log_disconnections=on from the CONNECTION string
+# was correctly passed through to and honored by the walsender.
+$logfile = slurp_file($node_publisher->logfile, $log_location);
+like(
+	$logfile,
+	qr/disconnection: session time:/,
+	'log_disconnections in CONNECTION string had effect on publisher\'s walsender');
+
 # check all the cleanup
 $node_subscriber->safe_psql('postgres', "DROP SUBSCRIPTION tap_sub_renamed");
 
-- 
2.51.2

From 1a1c412e2d320d82d7a6927e5e6550c554a77b23 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 26 Nov 2025 23:35:44 +0900
Subject: [PATCH v4] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 42 ++++++++++++++-----
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 02f12f29219..02f3ee15c87 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -178,17 +178,6 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 			/* Tell the publisher to translate to our encoding */
 			keys[++i] = "client_encoding";
 			vals[i] = GetDatabaseEncodingName();
-
-			/*
-			 * Force assorted GUC parameters to settings that ensure that the
-			 * publisher will output data values in a form that is unambiguous
-			 * to the subscriber.  (We don't want to modify the subscriber's
-			 * GUC settings, since that might surprise user-defined code
-			 * running in the subscriber, such as triggers.)  This should
-			 * match what pg_dump does.
-			 */
-			keys[++i] = "options";
-			vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
 		}
 		else
 		{
@@ -289,6 +278,37 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 		PQclear(res);
 	}
 
+	/*
+	 * Force assorted GUC parameters to settings that ensure that the
+	 * publisher will output data values in a form that is unambiguous to the
+	 * subscriber.  (We don't want to modify the subscriber's GUC settings,
+	 * since that might surprise user-defined code running in the subscriber,
+	 * such as triggers.)  This should match what pg_dump does.
+	 */
+	if (replication && logical)
+	{
+		const char *params[] =
+		{"datestyle", "intervalstyle", "extra_float_digits"};
+		const char *values[] = {"ISO", "postgres", "3"};
+
+		for (int j = 0; j < lengthof(params); j++)
+		{
+			char		sql[100];
+			PGresult   *res;
+
+			sprintf(sql, "SET %s = %s", params[j], values[j]);
+			res = libpqrcv_PQexec(conn->streamConn, sql);
+			if (PQresultStatus(res) != PGRES_COMMAND_OK)
+			{
+				PQclear(res);
+				*err = psprintf(_("could not set %s: %s"),
+								params[j], pchomp(PQerrorMessage(conn->streamConn)));
+				goto bad_connection;
+			}
+			PQclear(res);
+		}
+	}
+
 	conn->logical = logical;
 
 	return conn;
-- 
2.51.2

From f8e0dcdea82d08d65e30224da2339f58de8c5fc3 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 3 Dec 2025 00:59:09 +0900
Subject: [PATCH v5] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 61 ++++++++++++++++++-
 1 file changed, 60 insertions(+), 1 deletion(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 568024ec974..743f951f330 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -57,6 +57,8 @@ static void libpqrcv_get_senderinfo(WalReceiverConn *conn,
 									char **sender_host, int *sender_port);
 static char *libpqrcv_identify_system(WalReceiverConn *conn,
 									  TimeLineID *primary_tli);
+static char *libpqrcv_get_option_from_conninfo(const char *connInfo,
+											   const char *keyword);
 static int	libpqrcv_server_version(WalReceiverConn *conn);
 static void libpqrcv_readtimelinehistoryfile(WalReceiverConn *conn,
 											 TimeLineID tli, char **filename,
@@ -136,6 +138,7 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 	const char *keys[6];
 	const char *vals[6];
 	int			i = 0;
+	char	   *options_val = NULL;
 
 	/*
 	 * Re-validate connection string. The validation already happened at DDL
@@ -167,6 +170,8 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 	vals[i] = appname;
 	if (logical)
 	{
+		char	   *opt = NULL;
+
 		/* Tell the publisher to translate to our encoding */
 		keys[++i] = "client_encoding";
 		vals[i] = GetDatabaseEncodingName();
@@ -179,8 +184,13 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 		 * the subscriber, such as triggers.)  This should match what pg_dump
 		 * does.
 		 */
+		opt = libpqrcv_get_option_from_conninfo(conninfo, "options");
+		options_val = psprintf("%s -c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3",
+							   (opt == NULL) ? "" : opt);
 		keys[++i] = "options";
-		vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
+		vals[i] = options_val;
+		if (opt != NULL)
+			pfree(opt);
 	}
 	keys[++i] = NULL;
 	vals[i] = NULL;
@@ -232,6 +242,9 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 			status = PQconnectPoll(conn->streamConn);
 	} while (status != PGRES_POLLING_OK && status != PGRES_POLLING_FAILED);
 
+	if (options_val != NULL)
+		pfree(options_val);
+
 	if (PQstatus(conn->streamConn) != CONNECTION_OK)
 		goto bad_connection_errmsg;
 
@@ -434,6 +447,7 @@ libpqrcv_identify_system(WalReceiverConn *conn, TimeLineID *primary_tli)
 						"the primary server: %s",
 						pchomp(PQerrorMessage(conn->streamConn)))));
 	}
+
 	/*
 	 * IDENTIFY_SYSTEM returns 3 columns in 9.3 and earlier, and 4 columns in
 	 * 9.4 and onwards.
@@ -466,6 +480,51 @@ libpqrcv_server_version(WalReceiverConn *conn)
 	return PQserverVersion(conn->streamConn);
 }
 
+/*
+ * Get the value of the option with the given keyword from the primary
+ * server's conninfo.
+ *
+ * If the option is not found in connInfo, return NULL value.
+ */
+static char *
+libpqrcv_get_option_from_conninfo(const char *connInfo, const char *keyword)
+{
+	PQconninfoOption *opts;
+	char	   *option = NULL;
+	char	   *err = NULL;
+
+	opts = PQconninfoParse(connInfo, &err);
+	if (opts == NULL)
+	{
+		/* The error string is malloc'd, so we must free it explicitly */
+		char	   *errcopy = err ? pstrdup(err) : "out of memory";
+
+		PQfreemem(err);
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("invalid connection string syntax: %s", errcopy)));
+	}
+
+	for (PQconninfoOption *opt = opts; opt->keyword != NULL; ++opt)
+	{
+		/*
+		 * If the same option appears multiple times, then the last one will
+		 * be returned
+		 */
+		if (strcmp(opt->keyword, keyword) == 0 && opt->val &&
+			*opt->val)
+		{
+			if (option)
+				pfree(option);
+
+			option = pstrdup(opt->val);
+		}
+	}
+
+	PQconninfoFree(opts);
+	return option;
+}
+
 /*
  * Start streaming WAL data from given streaming options.
  *
-- 
2.51.2

From ad7ac7f3d88b6178cb50e2b64982bf89589c3655 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Thu, 27 Nov 2025 12:36:59 +0900
Subject: [PATCH v5 2/2] Add TAP test for GUC settings passed via CONNECTION in
 logical replication.

This commit adds a TAP test to verify that GUC settings provided in
the CONNECTION string of CREATE/ALTER SUBSCRIPTION are correctly
passed through to and applied by the publisher's walsender.
---
 src/test/subscription/t/001_rep_changes.pl | 29 +++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index 430c1246d14..c044a1e63e1 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -438,17 +438,34 @@ is( $result, qq(11.11|baz|1
 22.22|bar|2),
 	'update works with dropped subscriber column');
 
+# Verify that GUC settings supplied in the CONNECTION string take effect on
+# the publisher's walsender.  We do this by enabling log_disconnections in
+# the CONNECTION string later and checking that the publisher's log contains a
+# disconnection message.
+#
+# First, confirm that no such disconnection message appears before enabling
+# log_disconnections.
+$logfile = slurp_file($node_publisher->logfile, $log_location);
+unlike(
+	$logfile,
+	qr/disconnection: session time:/,
+	'log_disconnections has not been enabled yet');
+
 # check that change of connection string and/or publication list causes
 # restart of subscription workers. We check the state along with
 # application_name to ensure that the walsender is (re)started.
 #
 # Not all of these are registered as tests as we need to poll for a change
 # but the test suite will fail nonetheless when something goes wrong.
+#
+# Enable log_disconnections as the change of connection string,
+# which is also for the above mentioned test of GUC settings passed through
+# CONNECTION.
 my $oldpid = $node_publisher->safe_psql('postgres',
 	"SELECT pid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
 );
 $node_subscriber->safe_psql('postgres',
-	"ALTER SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr sslmode=disable'"
+	"ALTER SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr options=''-c log_disconnections=on'''"
 );
 $node_publisher->poll_query_until('postgres',
 	"SELECT pid != $oldpid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
@@ -552,6 +569,16 @@ $node_publisher->poll_query_until('postgres',
   or die
   "Timed out while waiting for apply to restart after renaming SUBSCRIPTION";
 
+# Check that the expected disconnection message appears,
+# which shows that log_disconnections=on from the CONNECTION string
+# was correctly passed through to and honored by the walsender.
+$logfile = slurp_file($node_publisher->logfile, $log_location);
+like(
+	$logfile,
+	qr/disconnection: session time:/,
+	'log_disconnections in CONNECTION string had effect on publisher\'s walsender'
+);
+
 # check all the cleanup
 $node_subscriber->safe_psql('postgres', "DROP SUBSCRIPTION tap_sub_renamed");
 
-- 
2.51.2

From c3e510636e8b7a1cce0657d86d6a29097544ee99 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 3 Dec 2025 00:59:09 +0900
Subject: [PATCH v5 1/2] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 43 +++++++++++++++----
 1 file changed, 34 insertions(+), 9 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 5ddc9e812e7..c067908da35 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -65,6 +65,8 @@ static void libpqrcv_get_senderinfo(WalReceiverConn *conn,
 static char *libpqrcv_identify_system(WalReceiverConn *conn,
 									  TimeLineID *primary_tli);
 static char *libpqrcv_get_dbname_from_conninfo(const char *connInfo);
+static char *libpqrcv_get_option_from_conninfo(const char *connInfo,
+											   const char *keyword);
 static int	libpqrcv_server_version(WalReceiverConn *conn);
 static void libpqrcv_readtimelinehistoryfile(WalReceiverConn *conn,
 											 TimeLineID tli, char **filename,
@@ -150,6 +152,7 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 	const char *keys[6];
 	const char *vals[6];
 	int			i = 0;
+	char	   *options_val = NULL;
 
 	/*
 	 * Re-validate connection string. The validation already happened at DDL
@@ -177,6 +180,8 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 
 		if (logical)
 		{
+			char	   *opt = NULL;
+
 			/* Tell the publisher to translate to our encoding */
 			keys[++i] = "client_encoding";
 			vals[i] = GetDatabaseEncodingName();
@@ -189,8 +194,13 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 			 * running in the subscriber, such as triggers.)  This should
 			 * match what pg_dump does.
 			 */
+			opt = libpqrcv_get_option_from_conninfo(conninfo, "options");
+			options_val = psprintf("%s -c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3",
+								   (opt == NULL) ? "" : opt);
 			keys[++i] = "options";
-			vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
+			vals[i] = options_val;
+			if (opt != NULL)
+				pfree(opt);
 		}
 		else
 		{
@@ -217,6 +227,9 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 								 /* expand_dbname = */ true,
 								WAIT_EVENT_LIBPQWALRECEIVER_CONNECT);
 
+	if (options_val != NULL)
+		pfree(options_val);
+
 	if (PQstatus(conn->streamConn) != CONNECTION_OK)
 		goto bad_connection_errmsg;
 
@@ -460,9 +473,21 @@ libpqrcv_server_version(WalReceiverConn *conn)
  */
 static char *
 libpqrcv_get_dbname_from_conninfo(const char *connInfo)
+{
+	return libpqrcv_get_option_from_conninfo(connInfo, "dbname");
+}
+
+/*
+ * Get the value of the option with the given keyword from the primary
+ * server's conninfo.
+ *
+ * If the option is not found in connInfo, return NULL value.
+ */
+static char *
+libpqrcv_get_option_from_conninfo(const char *connInfo, const char *keyword)
 {
 	PQconninfoOption *opts;
-	char	   *dbname = NULL;
+	char	   *option = NULL;
 	char	   *err = NULL;
 
 	opts = PQconninfoParse(connInfo, &err);
@@ -480,21 +505,21 @@ libpqrcv_get_dbname_from_conninfo(const char *connInfo)
 	for (PQconninfoOption *opt = opts; opt->keyword != NULL; ++opt)
 	{
 		/*
-		 * If multiple dbnames are specified, then the last one will be
-		 * returned
+		 * If the same option appears multiple times, then the last one will
+		 * be returned
 		 */
-		if (strcmp(opt->keyword, "dbname") == 0 && opt->val &&
+		if (strcmp(opt->keyword, keyword) == 0 && opt->val &&
 			*opt->val)
 		{
-			if (dbname)
-				pfree(dbname);
+			if (option)
+				pfree(option);
 
-			dbname = pstrdup(opt->val);
+			option = pstrdup(opt->val);
 		}
 	}
 
 	PQconninfoFree(opts);
-	return dbname;
+	return option;
 }
 
 /*
-- 
2.51.2

From a29e80e158b043a76f00383705ee9c27f3f864a5 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 3 Dec 2025 00:59:09 +0900
Subject: [PATCH v6 1/2] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 61 ++++++++++++++++++-
 1 file changed, 60 insertions(+), 1 deletion(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 568024ec974..743f951f330 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -57,6 +57,8 @@ static void libpqrcv_get_senderinfo(WalReceiverConn *conn,
 									char **sender_host, int *sender_port);
 static char *libpqrcv_identify_system(WalReceiverConn *conn,
 									  TimeLineID *primary_tli);
+static char *libpqrcv_get_option_from_conninfo(const char *connInfo,
+											   const char *keyword);
 static int	libpqrcv_server_version(WalReceiverConn *conn);
 static void libpqrcv_readtimelinehistoryfile(WalReceiverConn *conn,
 											 TimeLineID tli, char **filename,
@@ -136,6 +138,7 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 	const char *keys[6];
 	const char *vals[6];
 	int			i = 0;
+	char	   *options_val = NULL;
 
 	/*
 	 * Re-validate connection string. The validation already happened at DDL
@@ -167,6 +170,8 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 	vals[i] = appname;
 	if (logical)
 	{
+		char	   *opt = NULL;
+
 		/* Tell the publisher to translate to our encoding */
 		keys[++i] = "client_encoding";
 		vals[i] = GetDatabaseEncodingName();
@@ -179,8 +184,13 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 		 * the subscriber, such as triggers.)  This should match what pg_dump
 		 * does.
 		 */
+		opt = libpqrcv_get_option_from_conninfo(conninfo, "options");
+		options_val = psprintf("%s -c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3",
+							   (opt == NULL) ? "" : opt);
 		keys[++i] = "options";
-		vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
+		vals[i] = options_val;
+		if (opt != NULL)
+			pfree(opt);
 	}
 	keys[++i] = NULL;
 	vals[i] = NULL;
@@ -232,6 +242,9 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 			status = PQconnectPoll(conn->streamConn);
 	} while (status != PGRES_POLLING_OK && status != PGRES_POLLING_FAILED);
 
+	if (options_val != NULL)
+		pfree(options_val);
+
 	if (PQstatus(conn->streamConn) != CONNECTION_OK)
 		goto bad_connection_errmsg;
 
@@ -434,6 +447,7 @@ libpqrcv_identify_system(WalReceiverConn *conn, TimeLineID *primary_tli)
 						"the primary server: %s",
 						pchomp(PQerrorMessage(conn->streamConn)))));
 	}
+
 	/*
 	 * IDENTIFY_SYSTEM returns 3 columns in 9.3 and earlier, and 4 columns in
 	 * 9.4 and onwards.
@@ -466,6 +480,51 @@ libpqrcv_server_version(WalReceiverConn *conn)
 	return PQserverVersion(conn->streamConn);
 }
 
+/*
+ * Get the value of the option with the given keyword from the primary
+ * server's conninfo.
+ *
+ * If the option is not found in connInfo, return NULL value.
+ */
+static char *
+libpqrcv_get_option_from_conninfo(const char *connInfo, const char *keyword)
+{
+	PQconninfoOption *opts;
+	char	   *option = NULL;
+	char	   *err = NULL;
+
+	opts = PQconninfoParse(connInfo, &err);
+	if (opts == NULL)
+	{
+		/* The error string is malloc'd, so we must free it explicitly */
+		char	   *errcopy = err ? pstrdup(err) : "out of memory";
+
+		PQfreemem(err);
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("invalid connection string syntax: %s", errcopy)));
+	}
+
+	for (PQconninfoOption *opt = opts; opt->keyword != NULL; ++opt)
+	{
+		/*
+		 * If the same option appears multiple times, then the last one will
+		 * be returned
+		 */
+		if (strcmp(opt->keyword, keyword) == 0 && opt->val &&
+			*opt->val)
+		{
+			if (option)
+				pfree(option);
+
+			option = pstrdup(opt->val);
+		}
+	}
+
+	PQconninfoFree(opts);
+	return option;
+}
+
 /*
  * Start streaming WAL data from given streaming options.
  *
-- 
2.51.2

From 0e49936016a81eccf095cf710aa6c5ea1ca761cf Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Thu, 27 Nov 2025 12:36:59 +0900
Subject: [PATCH v6 2/2] Add TAP test for GUC settings passed via CONNECTION in
 logical replication.

This commit adds a TAP test to verify that GUC settings provided in
the CONNECTION string of CREATE/ALTER SUBSCRIPTION are correctly
passed through to and applied by the publisher's walsender.
---
 src/test/subscription/t/001_rep_changes.pl | 29 +++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index 430c1246d14..9db7e8219de 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -438,17 +438,34 @@ is( $result, qq(11.11|baz|1
 22.22|bar|2),
 	'update works with dropped subscriber column');
 
+# Verify that GUC settings supplied in the CONNECTION string take effect on
+# the publisher's walsender.  We do this by enabling log_statement_stats in
+# the CONNECTION string later and checking that the publisher's log contains a
+# QUERY STATISTICS message.
+#
+# First, confirm that no such QUERY STATISTICS message appears before enabling
+# log_statement_stats.
+$logfile = slurp_file($node_publisher->logfile, $log_location);
+unlike(
+	$logfile,
+	qr/QUERY STATISTICS/,
+	'log_statement_stats has not been enabled yet');
+
 # check that change of connection string and/or publication list causes
 # restart of subscription workers. We check the state along with
 # application_name to ensure that the walsender is (re)started.
 #
 # Not all of these are registered as tests as we need to poll for a change
 # but the test suite will fail nonetheless when something goes wrong.
+#
+# Enable log_statement_stats as the change of connection string,
+# which is also for the above mentioned test of GUC settings passed through
+# CONNECTION.
 my $oldpid = $node_publisher->safe_psql('postgres',
 	"SELECT pid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
 );
 $node_subscriber->safe_psql('postgres',
-	"ALTER SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr sslmode=disable'"
+	"ALTER SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr options=''-c log_statement_stats=on'''"
 );
 $node_publisher->poll_query_until('postgres',
 	"SELECT pid != $oldpid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
@@ -552,6 +569,16 @@ $node_publisher->poll_query_until('postgres',
   or die
   "Timed out while waiting for apply to restart after renaming SUBSCRIPTION";
 
+# Check that the expected QUERY STATISTICS message appears,
+# which shows that log_statement_stats=on from the CONNECTION string
+# was correctly passed through to and honored by the walsender.
+$logfile = slurp_file($node_publisher->logfile, $log_location);
+like(
+	$logfile,
+	qr/QUERY STATISTICS/,
+	'log_statement_stats in CONNECTION string had effect on publisher\'s walsender'
+);
+
 # check all the cleanup
 $node_subscriber->safe_psql('postgres', "DROP SUBSCRIPTION tap_sub_renamed");
 
-- 
2.51.2

From ca378d99f617b4418261fce74e4f5ff84570a7e7 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 3 Dec 2025 00:59:09 +0900
Subject: [PATCH v6 1/2] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 43 +++++++++++++++----
 1 file changed, 34 insertions(+), 9 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 5ddc9e812e7..c067908da35 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -65,6 +65,8 @@ static void libpqrcv_get_senderinfo(WalReceiverConn *conn,
 static char *libpqrcv_identify_system(WalReceiverConn *conn,
 									  TimeLineID *primary_tli);
 static char *libpqrcv_get_dbname_from_conninfo(const char *connInfo);
+static char *libpqrcv_get_option_from_conninfo(const char *connInfo,
+											   const char *keyword);
 static int	libpqrcv_server_version(WalReceiverConn *conn);
 static void libpqrcv_readtimelinehistoryfile(WalReceiverConn *conn,
 											 TimeLineID tli, char **filename,
@@ -150,6 +152,7 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 	const char *keys[6];
 	const char *vals[6];
 	int			i = 0;
+	char	   *options_val = NULL;
 
 	/*
 	 * Re-validate connection string. The validation already happened at DDL
@@ -177,6 +180,8 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 
 		if (logical)
 		{
+			char	   *opt = NULL;
+
 			/* Tell the publisher to translate to our encoding */
 			keys[++i] = "client_encoding";
 			vals[i] = GetDatabaseEncodingName();
@@ -189,8 +194,13 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 			 * running in the subscriber, such as triggers.)  This should
 			 * match what pg_dump does.
 			 */
+			opt = libpqrcv_get_option_from_conninfo(conninfo, "options");
+			options_val = psprintf("%s -c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3",
+								   (opt == NULL) ? "" : opt);
 			keys[++i] = "options";
-			vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
+			vals[i] = options_val;
+			if (opt != NULL)
+				pfree(opt);
 		}
 		else
 		{
@@ -217,6 +227,9 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 								 /* expand_dbname = */ true,
 								WAIT_EVENT_LIBPQWALRECEIVER_CONNECT);
 
+	if (options_val != NULL)
+		pfree(options_val);
+
 	if (PQstatus(conn->streamConn) != CONNECTION_OK)
 		goto bad_connection_errmsg;
 
@@ -460,9 +473,21 @@ libpqrcv_server_version(WalReceiverConn *conn)
  */
 static char *
 libpqrcv_get_dbname_from_conninfo(const char *connInfo)
+{
+	return libpqrcv_get_option_from_conninfo(connInfo, "dbname");
+}
+
+/*
+ * Get the value of the option with the given keyword from the primary
+ * server's conninfo.
+ *
+ * If the option is not found in connInfo, return NULL value.
+ */
+static char *
+libpqrcv_get_option_from_conninfo(const char *connInfo, const char *keyword)
 {
 	PQconninfoOption *opts;
-	char	   *dbname = NULL;
+	char	   *option = NULL;
 	char	   *err = NULL;
 
 	opts = PQconninfoParse(connInfo, &err);
@@ -480,21 +505,21 @@ libpqrcv_get_dbname_from_conninfo(const char *connInfo)
 	for (PQconninfoOption *opt = opts; opt->keyword != NULL; ++opt)
 	{
 		/*
-		 * If multiple dbnames are specified, then the last one will be
-		 * returned
+		 * If the same option appears multiple times, then the last one will
+		 * be returned
 		 */
-		if (strcmp(opt->keyword, "dbname") == 0 && opt->val &&
+		if (strcmp(opt->keyword, keyword) == 0 && opt->val &&
 			*opt->val)
 		{
-			if (dbname)
-				pfree(dbname);
+			if (option)
+				pfree(option);
 
-			dbname = pstrdup(opt->val);
+			option = pstrdup(opt->val);
 		}
 	}
 
 	PQconninfoFree(opts);
-	return dbname;
+	return option;
 }
 
 /*
-- 
2.51.2

From 38798c9bc99f0499bea754f3d6a51d5244163360 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 3 Dec 2025 00:59:09 +0900
Subject: [PATCH v7 1/2] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 61 ++++++++++++++++++-
 1 file changed, 60 insertions(+), 1 deletion(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 568024ec974..743f951f330 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -57,6 +57,8 @@ static void libpqrcv_get_senderinfo(WalReceiverConn *conn,
 									char **sender_host, int *sender_port);
 static char *libpqrcv_identify_system(WalReceiverConn *conn,
 									  TimeLineID *primary_tli);
+static char *libpqrcv_get_option_from_conninfo(const char *connInfo,
+											   const char *keyword);
 static int	libpqrcv_server_version(WalReceiverConn *conn);
 static void libpqrcv_readtimelinehistoryfile(WalReceiverConn *conn,
 											 TimeLineID tli, char **filename,
@@ -136,6 +138,7 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 	const char *keys[6];
 	const char *vals[6];
 	int			i = 0;
+	char	   *options_val = NULL;
 
 	/*
 	 * Re-validate connection string. The validation already happened at DDL
@@ -167,6 +170,8 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 	vals[i] = appname;
 	if (logical)
 	{
+		char	   *opt = NULL;
+
 		/* Tell the publisher to translate to our encoding */
 		keys[++i] = "client_encoding";
 		vals[i] = GetDatabaseEncodingName();
@@ -179,8 +184,13 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 		 * the subscriber, such as triggers.)  This should match what pg_dump
 		 * does.
 		 */
+		opt = libpqrcv_get_option_from_conninfo(conninfo, "options");
+		options_val = psprintf("%s -c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3",
+							   (opt == NULL) ? "" : opt);
 		keys[++i] = "options";
-		vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
+		vals[i] = options_val;
+		if (opt != NULL)
+			pfree(opt);
 	}
 	keys[++i] = NULL;
 	vals[i] = NULL;
@@ -232,6 +242,9 @@ libpqrcv_connect(const char *conninfo, bool logical, bool must_use_password,
 			status = PQconnectPoll(conn->streamConn);
 	} while (status != PGRES_POLLING_OK && status != PGRES_POLLING_FAILED);
 
+	if (options_val != NULL)
+		pfree(options_val);
+
 	if (PQstatus(conn->streamConn) != CONNECTION_OK)
 		goto bad_connection_errmsg;
 
@@ -434,6 +447,7 @@ libpqrcv_identify_system(WalReceiverConn *conn, TimeLineID *primary_tli)
 						"the primary server: %s",
 						pchomp(PQerrorMessage(conn->streamConn)))));
 	}
+
 	/*
 	 * IDENTIFY_SYSTEM returns 3 columns in 9.3 and earlier, and 4 columns in
 	 * 9.4 and onwards.
@@ -466,6 +480,51 @@ libpqrcv_server_version(WalReceiverConn *conn)
 	return PQserverVersion(conn->streamConn);
 }
 
+/*
+ * Get the value of the option with the given keyword from the primary
+ * server's conninfo.
+ *
+ * If the option is not found in connInfo, return NULL value.
+ */
+static char *
+libpqrcv_get_option_from_conninfo(const char *connInfo, const char *keyword)
+{
+	PQconninfoOption *opts;
+	char	   *option = NULL;
+	char	   *err = NULL;
+
+	opts = PQconninfoParse(connInfo, &err);
+	if (opts == NULL)
+	{
+		/* The error string is malloc'd, so we must free it explicitly */
+		char	   *errcopy = err ? pstrdup(err) : "out of memory";
+
+		PQfreemem(err);
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("invalid connection string syntax: %s", errcopy)));
+	}
+
+	for (PQconninfoOption *opt = opts; opt->keyword != NULL; ++opt)
+	{
+		/*
+		 * If the same option appears multiple times, then the last one will
+		 * be returned
+		 */
+		if (strcmp(opt->keyword, keyword) == 0 && opt->val &&
+			*opt->val)
+		{
+			if (option)
+				pfree(option);
+
+			option = pstrdup(opt->val);
+		}
+	}
+
+	PQconninfoFree(opts);
+	return option;
+}
+
 /*
  * Start streaming WAL data from given streaming options.
  *
-- 
2.51.2

From 32f36d5bf49c5ec8b60aa05cc0e070b686b459ed Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Thu, 27 Nov 2025 12:36:59 +0900
Subject: [PATCH v7 2/2] Add TAP test for GUC settings passed via CONNECTION in
 logical replication.

This commit adds a TAP test to verify that GUC settings provided in
the CONNECTION string of CREATE/ALTER SUBSCRIPTION are correctly
passed through to and applied by the publisher's walsender.
---
 src/test/subscription/t/001_rep_changes.pl | 29 +++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index ecb79e79474..4eab249d62e 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -438,17 +438,34 @@ is( $result, qq(11.11|baz|1
 22.22|bar|2),
 	'update works with dropped subscriber column');
 
+# Verify that GUC settings supplied in the CONNECTION string take effect on
+# the publisher's walsender.  We do this by enabling log_statement_stats in
+# the CONNECTION string later and checking that the publisher's log contains a
+# QUERY STATISTICS message.
+#
+# First, confirm that no such QUERY STATISTICS message appears before enabling
+# log_statement_stats.
+$logfile = slurp_file($node_publisher->logfile, $log_location);
+unlike(
+	$logfile,
+	qr/QUERY STATISTICS/,
+	'log_statement_stats has not been enabled yet');
+
 # check that change of connection string and/or publication list causes
 # restart of subscription workers. We check the state along with
 # application_name to ensure that the walsender is (re)started.
 #
 # Not all of these are registered as tests as we need to poll for a change
 # but the test suite will fail nonetheless when something goes wrong.
+#
+# Enable log_statement_stats as the change of connection string,
+# which is also for the above mentioned test of GUC settings passed through
+# CONNECTION.
 my $oldpid = $node_publisher->safe_psql('postgres',
 	"SELECT pid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
 );
 $node_subscriber->safe_psql('postgres',
-	"ALTER SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr sslmode=disable'"
+	"ALTER SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr options=''-c log_statement_stats=on'''"
 );
 $node_publisher->poll_query_until('postgres',
 	"SELECT pid != $oldpid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
@@ -456,6 +473,16 @@ $node_publisher->poll_query_until('postgres',
   or die
   "Timed out while waiting for apply to restart after changing CONNECTION";
 
+# Check that the expected QUERY STATISTICS message appears,
+# which shows that log_statement_stats=on from the CONNECTION string
+# was correctly passed through to and honored by the walsender.
+$logfile = slurp_file($node_publisher->logfile, $log_location);
+like(
+	$logfile,
+	qr/QUERY STATISTICS/,
+	'log_statement_stats in CONNECTION string had effect on publisher\'s walsender'
+);
+
 $oldpid = $node_publisher->safe_psql('postgres',
 	"SELECT pid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
 );
-- 
2.51.2

From 84d9dfd3e7d49c318dfad78c31cd5ca620b31877 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Wed, 3 Dec 2025 00:59:09 +0900
Subject: [PATCH v7 1/2] Honor GUC settings specified in CREATE SUBSCRIPTION
 CONNECTION.

Prior to v15, GUC settings supplied in the CONNECTION clause of
CREATE SUBSCRIPTION were correctly passed through to
the publisher's walsender. For example:

        CREATE SUBSCRIPTION mysub
            CONNECTION 'options=''-c wal_sender_timeout=1000'''
            PUBLICATION ...

would cause wal_sender_timeout to take effect on the publisher's walsender.

However, commit f3d4019da5d changed the way logical replication
connections are established, forcing the publisher's relevant
GUC settings (datestyle, intervalstyle, extra_float_digits) to
override those provided in the CONNECTION string. As a result,
from v15 through v18, GUC settings in the CONNECTION string were
always ignored.

This regression prevented per-connection tuning of logical replication.
For example, using a shorter timeout for walsender connecting
to a nearby subscriber and a longer one for walsender connecting
to a remote subscriber.

This commit restores the intended behavior by ensuring that
GUC settings in the CONNECTION string are again passed through
and applied by the walsender, allowing per-connection configuration.

Backpatch to v15, where the regression was introduced.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Discussion: https://postgr.es/m/CAHGQGwGYV+-abbKwdrM2UHUe-JYOFWmsrs6=QicyJO-j+-Widw@mail.gmail.com
Backpatch-through: 15
---
 .../libpqwalreceiver/libpqwalreceiver.c       | 43 +++++++++++++++----
 1 file changed, 34 insertions(+), 9 deletions(-)

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 5ddc9e812e7..c067908da35 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -65,6 +65,8 @@ static void libpqrcv_get_senderinfo(WalReceiverConn *conn,
 static char *libpqrcv_identify_system(WalReceiverConn *conn,
 									  TimeLineID *primary_tli);
 static char *libpqrcv_get_dbname_from_conninfo(const char *connInfo);
+static char *libpqrcv_get_option_from_conninfo(const char *connInfo,
+											   const char *keyword);
 static int	libpqrcv_server_version(WalReceiverConn *conn);
 static void libpqrcv_readtimelinehistoryfile(WalReceiverConn *conn,
 											 TimeLineID tli, char **filename,
@@ -150,6 +152,7 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 	const char *keys[6];
 	const char *vals[6];
 	int			i = 0;
+	char	   *options_val = NULL;
 
 	/*
 	 * Re-validate connection string. The validation already happened at DDL
@@ -177,6 +180,8 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 
 		if (logical)
 		{
+			char	   *opt = NULL;
+
 			/* Tell the publisher to translate to our encoding */
 			keys[++i] = "client_encoding";
 			vals[i] = GetDatabaseEncodingName();
@@ -189,8 +194,13 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 			 * running in the subscriber, such as triggers.)  This should
 			 * match what pg_dump does.
 			 */
+			opt = libpqrcv_get_option_from_conninfo(conninfo, "options");
+			options_val = psprintf("%s -c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3",
+								   (opt == NULL) ? "" : opt);
 			keys[++i] = "options";
-			vals[i] = "-c datestyle=ISO -c intervalstyle=postgres -c extra_float_digits=3";
+			vals[i] = options_val;
+			if (opt != NULL)
+				pfree(opt);
 		}
 		else
 		{
@@ -217,6 +227,9 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 								 /* expand_dbname = */ true,
 								WAIT_EVENT_LIBPQWALRECEIVER_CONNECT);
 
+	if (options_val != NULL)
+		pfree(options_val);
+
 	if (PQstatus(conn->streamConn) != CONNECTION_OK)
 		goto bad_connection_errmsg;
 
@@ -460,9 +473,21 @@ libpqrcv_server_version(WalReceiverConn *conn)
  */
 static char *
 libpqrcv_get_dbname_from_conninfo(const char *connInfo)
+{
+	return libpqrcv_get_option_from_conninfo(connInfo, "dbname");
+}
+
+/*
+ * Get the value of the option with the given keyword from the primary
+ * server's conninfo.
+ *
+ * If the option is not found in connInfo, return NULL value.
+ */
+static char *
+libpqrcv_get_option_from_conninfo(const char *connInfo, const char *keyword)
 {
 	PQconninfoOption *opts;
-	char	   *dbname = NULL;
+	char	   *option = NULL;
 	char	   *err = NULL;
 
 	opts = PQconninfoParse(connInfo, &err);
@@ -480,21 +505,21 @@ libpqrcv_get_dbname_from_conninfo(const char *connInfo)
 	for (PQconninfoOption *opt = opts; opt->keyword != NULL; ++opt)
 	{
 		/*
-		 * If multiple dbnames are specified, then the last one will be
-		 * returned
+		 * If the same option appears multiple times, then the last one will
+		 * be returned
 		 */
-		if (strcmp(opt->keyword, "dbname") == 0 && opt->val &&
+		if (strcmp(opt->keyword, keyword) == 0 && opt->val &&
 			*opt->val)
 		{
-			if (dbname)
-				pfree(dbname);
+			if (option)
+				pfree(option);
 
-			dbname = pstrdup(opt->val);
+			option = pstrdup(opt->val);
 		}
 	}
 
 	PQconninfoFree(opts);
-	return dbname;
+	return option;
 }
 
 /*
-- 
2.51.2