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[PATCH 2/2] Remove dsm_seg from DecodingWorkerShared.
813+ messages / 2 participants
[nested] [flat]

* [PATCH 2/2] Remove dsm_seg from DecodingWorkerShared.
@ 2026-04-13 09:36  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Antonin Houska @ 2026-04-13 09:36 UTC (permalink / raw)

The value is only needed by te worker, so there is no need to store it in
shared memory.
---
 src/backend/commands/repack_worker.c   | 5 +++--
 src/include/commands/repack_internal.h | 1 -
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 5bd020e0184..a594d6db25f 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -51,6 +51,7 @@ static XLogSegNo repack_current_segment = 0;
 static RelFileLocator repacked_rel_locator = {.relNumber = InvalidOid};
 static RelFileLocator repacked_rel_toast_locator = {.relNumber = InvalidOid};
 
+static dsm_segment	*worker_dsm_segment = NULL;
 
 /* REPACK decoding worker entry point */
 void
@@ -78,9 +79,9 @@ RepackWorkerMain(Datum main_arg)
 		ereport(ERROR,
 				errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 				errmsg("could not map dynamic shared memory segment"));
+	worker_dsm_segment = seg;
 
 	shared = (DecodingWorkerShared *) dsm_segment_address(seg);
-	shared->dsm_seg = seg;
 
 	/* Arrange to signal the leader if we exit. */
 	before_shmem_exit(RepackWorkerShutdown, PointerGetDatum(shared));
@@ -176,7 +177,7 @@ RepackWorkerShutdown(int code, Datum arg)
 				   PROCSIG_REPACK_MESSAGE,
 				   shared->backend_proc_number);
 
-	dsm_detach(shared->dsm_seg);
+	dsm_detach(worker_dsm_segment);
 }
 
 bool
diff --git a/src/include/commands/repack_internal.h b/src/include/commands/repack_internal.h
index 3ff64444351..6a85cee8910 100644
--- a/src/include/commands/repack_internal.h
+++ b/src/include/commands/repack_internal.h
@@ -107,7 +107,6 @@ typedef struct DecodingWorkerShared
 	PGPROC	   *backend_proc;
 	pid_t		backend_pid;
 	ProcNumber	backend_proc_number;
-	dsm_segment *dsm_seg;
 
 	/*
 	 * Memory the queue is located in.
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



^ permalink  raw  reply  [nested|flat] 813+ messages in thread

* [PATCH v3 3/4] Add invalidation-based retry loop for Alter/Drop Subscription
@ 2026-07-03 14:03  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 813+ messages in thread

From: Bertrand Drouvot @ 2026-07-03 14:03 UTC (permalink / raw)

Following the approach of RangeVarGetRelidExtended() for relations, add a
retry loop that includes name resolution, ownership check, and lock
acquisition in AlterSubscription() and DropSubscription().

The loop records SharedInvalidMessageCounter, resolves the subscription name
to an OID, checks ownership, then locks the subscription. If the invalidation
counter changed (indicating concurrent DDL), we save the current OID and
retry. On the next iteration, if the name still resolves to the same OID,
we're done (already holding the correct lock). If it resolves to a different
OID, we release the old lock and acquire the new one.

This mirrors RangeVarGetRelidExtended()'s behavior: the lock is kept across
retries to avoid a window where another session could have committed concurrent
DDL modifying the ownership and/or the name resolution.

Author: Bertrand Drouvot <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/akZUpiDa1UfmzYxL%40bdtpg
---
 src/backend/commands/subscriptioncmds.c | 167 +++++++++++++++++-------
 1 file changed, 118 insertions(+), 49 deletions(-)
 100.0% src/backend/commands/

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index e23b366a87d..866341c2cfb 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -50,6 +50,7 @@
 #include "replication/walsender.h"
 #include "replication/worker_internal.h"
 #include "storage/lmgr.h"
+#include "storage/sinval.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/guc.h"
@@ -1592,23 +1593,67 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 
 	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
-	/* Fetch the existing tuple. */
-	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
-							  CStringGetDatum(stmt->subname));
+	/*
+	 * Lock the subscription so nobody else can do anything with it.
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
+	 */
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-	subid = form->oid;
+			tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME,
+									  ObjectIdGetDatum(MyDatabaseId),
+									  CStringGetDatum(stmt->subname));
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer. So we're done. If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			heap_freetuple(tup);
+		}
+	}
 
 	/* parse and check options */
 	switch (stmt->kind)
@@ -1686,25 +1731,6 @@ AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
 			orig_conninfo_needed = false;
 	}
 
-	heap_freetuple(tup);
-
-	/* Lock the subscription so nobody else can do anything with it. */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
-
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * DROP or ALTER may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
-
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
-
-	form = (Form_pg_subscription) GETSTRUCT(tup);
-
 	/*
 	 * Skip ACL checks on the subscription's foreign server, if any. If
 	 * changing the server (or replacing it with a raw connection), then the
@@ -2570,11 +2596,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subid = form->oid;
 
-	/* must be owner */
-	if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
-		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
-					   stmt->subname);
-
 	/* DROP hook for the subscription being removed */
 	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
@@ -2583,20 +2604,68 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/*
 	 * Lock the subscription so nobody else can do anything with it (including
 	 * the replication workers).
+	 *
+	 * Like RangeVarGetRelidExtended() does for relations, we resolve the
+	 * name, check ownership, and lock inside a loop. If invalidation messages
+	 * arrive (indicating concurrent DDL), we retry. We keep the lock held
+	 * across retries and only release it if the name resolves to a different
+	 * OID on the next iteration.
 	 */
-	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+	{
+		Oid			oldSubId = InvalidOid;
+		bool		retry = false;
 
-	/*
-	 * Re-read the subscription tuple after acquiring the lock. A concurrent
-	 * ALTER or DROP may have committed before we acquired the lock.
-	 */
-	tup = SearchSysCache1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+		for (;;)
+		{
+			uint64		inval_count = SharedInvalidMessageCounter;
 
-	if (!HeapTupleIsValid(tup))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("subscription \"%s\" does not exist",
-						stmt->subname)));
+			tup = SearchSysCache2(SUBSCRIPTIONNAME,
+								  ObjectIdGetDatum(MyDatabaseId),
+								  CStringGetDatum(stmt->subname));
+
+			if (!HeapTupleIsValid(tup))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("subscription \"%s\" does not exist",
+								stmt->subname)));
+
+			form = (Form_pg_subscription) GETSTRUCT(tup);
+			subid = form->oid;
+
+			if (!object_ownercheck(SubscriptionRelationId, subid,
+								   GetUserId()))
+			{
+				ReleaseSysCache(tup);
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+							   stmt->subname);
+			}
+
+			/*
+			 * If upon retry we get the same OID, the invalidation messages
+			 * did not change the final answer.  So we're done.  If we got a
+			 * different OID, unlock the old one and lock the new one below.
+			 */
+			if (retry)
+			{
+				if (subid == oldSubId)
+					break;
+				UnlockSharedObject(SubscriptionRelationId, oldSubId, 0,
+								   AccessExclusiveLock);
+			}
+
+			LockSharedObject(SubscriptionRelationId, subid, 0,
+							 AccessExclusiveLock);
+
+			/* If no invalidation messages, we're done. */
+			if (inval_count == SharedInvalidMessageCounter)
+				break;
+
+			/* Something may have changed, retry. */
+			retry = true;
+			oldSubId = subid;
+			ReleaseSysCache(tup);
+		}
+	}
 
 	form = (Form_pg_subscription) GETSTRUCT(tup);
 	subowner = form->subowner;
-- 
2.34.1


--3eAVwo4vDNlHc8RC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0004-Add-invalidation-based-retry-loop-for-AlterPublic.patch"



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