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[PATCH v51 05/10] invert meaning of index_create flag bit
131+ messages / 2 participants
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* [PATCH v51 05/10] invert meaning of index_create flag bit
@ 2026-04-03 19:08 Álvaro Herrera <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Álvaro Herrera @ 2026-04-03 19:08 UTC (permalink / raw)

---
 src/backend/catalog/index.c      | 20 +++++++++++---------
 src/backend/catalog/toasting.c   |  2 +-
 src/backend/commands/indexcmds.c |  1 -
 src/include/catalog/index.h      |  2 +-
 4 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 4b8ed2c7660..5a7c9d81917 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -715,9 +715,9 @@ UpdateIndexRelation(Oid indexoid,
  *			already exists.
  *		INDEX_CREATE_PARTITIONED:
  *			create a partitioned index (table must be partitioned)
- *		INDEX_CREATE_REPORT_PROGRESS:
- *			update the backend's progress information during index build.
-
+ *		INDEX_CREATE_SUPPRESS_PROGRESS:
+ *			don't report progress during the index build.
+ *
  * constr_flags: flags passed to index_constraint_create
  *		(only if INDEX_CREATE_ADD_CONSTRAINT is set)
  * allow_system_table_mods: allow table to be a system catalog
@@ -763,7 +763,7 @@ index_create(Relation heapRelation,
 	bool		invalid = (flags & INDEX_CREATE_INVALID) != 0;
 	bool		concurrent = (flags & INDEX_CREATE_CONCURRENT) != 0;
 	bool		partitioned = (flags & INDEX_CREATE_PARTITIONED) != 0;
-	bool		progress = (flags & INDEX_CREATE_REPORT_PROGRESS) != 0;
+	bool		progress = (flags & INDEX_CREATE_SUPPRESS_PROGRESS) == 0;
 	char		relkind;
 	TransactionId relfrozenxid;
 	MultiXactId relminmxid;
@@ -1454,13 +1454,15 @@ index_create_copy(Relation heapRelation, bool concurrently,
 	}
 
 	/*
-	 * Note: The current callers do not need INDEX_CREATE_REPORT_PROGRESS. If
-	 * 'concurrently' is true, there is no build at all. Otherwise the index
-	 * build is a sub-command of REPACK. The current infrastructure does not
-	 * allow two commands to report their progress at the same time.
+	 * The current callers do not need to report progress: if 'concurrently' is
+	 * true, there is no build at all to report about; and otherwise the index
+	 * build is a sub-command of REPACK, and the current progress reporting
+	 * infrastructure does not allow two commands to report their progress at
+	 * the same time.
 	 */
 	if (concurrently)
-		flags = INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT;
+		flags = INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT |
+			INDEX_CREATE_SUPPRESS_PROGRESS;
 
 	/*
 	 * Now create the new index.
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index 51b27a8c71c..dcee536fd3f 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -332,7 +332,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 				 BTREE_AM_OID,
 				 rel->rd_rel->reltablespace,
 				 collationIds, opclassIds, NULL, coloptions, NULL, (Datum) 0,
-				 INDEX_CREATE_IS_PRIMARY | INDEX_CREATE_REPORT_PROGRESS, 0,
+				 INDEX_CREATE_IS_PRIMARY, 0,
 				 true, true, NULL);
 
 	table_close(toast_rel, NoLock);
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 932924c13e0..cba379810c7 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1231,7 +1231,6 @@ DefineIndex(ParseState *pstate,
 		flags |= INDEX_CREATE_PARTITIONED;
 	if (stmt->primary)
 		flags |= INDEX_CREATE_IS_PRIMARY;
-	flags |= INDEX_CREATE_REPORT_PROGRESS;
 
 	/*
 	 * If the table is partitioned, and recursion was declined but partitions
diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h
index 7ebe4f0bd87..9f538dac798 100644
--- a/src/include/catalog/index.h
+++ b/src/include/catalog/index.h
@@ -71,7 +71,7 @@ extern void index_check_primary_key(Relation heapRel,
 #define	INDEX_CREATE_IF_NOT_EXISTS			(1 << 4)
 #define	INDEX_CREATE_PARTITIONED			(1 << 5)
 #define INDEX_CREATE_INVALID				(1 << 6)
-#define INDEX_CREATE_REPORT_PROGRESS		(1 << 7)
+#define INDEX_CREATE_SUPPRESS_PROGRESS		(1 << 7)
 
 extern Oid	index_create(Relation heapRelation,
 						 const char *indexRelationName,
-- 
2.47.3


--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
	filename="v51-0006-Error-out-any-process-that-would-block-at-REPACK.patch"



^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--=-=-=--





^ permalink  raw  reply  [nested|flat] 131+ messages in thread

* [PATCH 3/3] Distinguish properly when database-specific transaction list should be used.
@ 2026-05-06 07:38 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 131+ messages in thread

From: Antonin Houska @ 2026-05-06 07:38 UTC (permalink / raw)

Currently, decoding session that relies on database-specific xl_running_xacts
WAL records can also use some information of cluster-wide records and vice
versa. Although this approach might reduce the total number of
xl_running_xacts records, it's simply not correct.

SnapBuildProcessRunningXacts() now decides at the very beginning whether
particular record can be used or not.
---
 src/backend/replication/logical/snapbuild.c | 55 +++++++++++++--------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index c8309b96ed4..b9661b7d70a 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1157,6 +1157,39 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	ReorderBufferTXN *txn;
 	TransactionId xmin;
 
+	/*
+	 * Each decoding session should use either cluster-wide snapshots or
+	 * database-specific ones, but not both. Since the latter can have more
+	 * recent value of oldestRunningXid, builder->xmin could go backwards if
+	 * it was followed by cluster-wide snapshot - see the ->xmin adjustment
+	 * below.
+	 */
+	if (!db_specific && OidIsValid(running->dbid))
+		return;
+
+	if (db_specific)
+	{
+		/*
+		 * Make sure that we have the snapshots needed for startup, as well as
+		 * those for regular cleanup: each time the cluster-wide snapshot is
+		 * created (typically on slot creation or by checkpointer), the
+		 * database-specific snapshot is requested here if the current session
+		 * needs it.
+		 */
+		if (!OidIsValid(running->dbid))
+		{
+			LogStandbySnapshot(MyDatabaseId);
+
+			return;
+		}
+		/*
+		 * Snapshots issued for other databases do not contain the information
+		 * about transactions in our database.
+		 */
+		else if (running->dbid != MyDatabaseId)
+			return;
+	}
+
 	/*
 	 * If we're not consistent yet, inspect the record to see whether it
 	 * allows to get closer to being consistent. If we are consistent, dump
@@ -1171,17 +1204,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		 */
 		if (db_specific)
 		{
-			/*
-			 * If we must only keep track of transactions running in the
-			 * current database, we need transaction info from exactly that
-			 * database.
-			 */
-			if (running->dbid != MyDatabaseId)
-			{
-				LogStandbySnapshot(MyDatabaseId);
-
-				return;
-			}
+			Assert(running->dbid == MyDatabaseId);
 
 			/*
 			 * We'd better be able to check during scan if the plugin does not
@@ -1198,16 +1221,6 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	else
 		SnapBuildSerialize(builder, lsn);
 
-	/*
-	 * Database specific transaction info may exist to reach CONSISTENT state
-	 * faster, however the code below makes no use of it. Moreover, such
-	 * record might cause problems because the following normal (cluster-wide)
-	 * record can have lower value of oldestRunningXid. In that case, let's
-	 * wait with the cleanup for the next regular cluster-wide record.
-	 */
-	if (OidIsValid(running->dbid))
-		return;
-
 	/*
 	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
-- 
2.47.3


--tbdehtstrqwksfdh--





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