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[PATCH v28 03/11] Allow to prolong life span of transition tables until transaction end
324+ messages / 2 participants
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* [PATCH v28 03/11] Allow to prolong life span of transition tables until transaction end
@ 2019-12-20 01:09 Yugo Nagata <nagata@sraoss.co.jp>
  0 siblings, 0 replies; 324+ messages in thread

From: Yugo Nagata @ 2019-12-20 01:09 UTC (permalink / raw)

Originally, tuplestores of AFTER trigger's transition tables were
freed for each query depth. For our IVM implementation, we would like
to prolong life of the tuplestores because we have to preserve them
for a whole query assuming that some base tables might be changed
in some trigger functions.
---
 src/backend/commands/trigger.c | 83 ++++++++++++++++++++++++++++++++--
 src/include/commands/trigger.h |  2 +
 2 files changed, 81 insertions(+), 4 deletions(-)

diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index 4b295f8da5..354ea94777 100644
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -3742,6 +3742,10 @@ typedef struct AfterTriggerEventList
  * end of the list, so it is relatively easy to discard them.  The event
  * list chunks themselves are stored in event_cxt.
  *
+ * prolonged_tuplestored is a list of transition table tuplestores whose
+ * life are prolonged to the end of the outmost query instead of each nested
+ * query.
+ *
  * query_depth is the current depth of nested AfterTriggerBeginQuery calls
  * (-1 when the stack is empty).
  *
@@ -3807,6 +3811,7 @@ typedef struct AfterTriggersData
 	SetConstraintState state;	/* the active S C state */
 	AfterTriggerEventList events;	/* deferred-event list */
 	MemoryContext event_cxt;	/* memory context for events, if any */
+	List   *prolonged_tuplestores;	/* list of prolonged tuplestores */
 
 	/* per-query-level data: */
 	AfterTriggersQueryData *query_stack;	/* array of structs shown below */
@@ -3842,6 +3847,7 @@ struct AfterTriggersTableData
 	bool		closed;			/* true when no longer OK to add tuples */
 	bool		before_trig_done;	/* did we already queue BS triggers? */
 	bool		after_trig_done;	/* did we already queue AS triggers? */
+	bool		prolonged;			/* are transition tables prolonged? */
 	AfterTriggerEventList after_trig_events;	/* if so, saved list pointer */
 
 	/*
@@ -3891,6 +3897,7 @@ static void TransitionTableAddTuple(EState *estate,
 									TupleTableSlot *original_insert_tuple,
 									Tuplestorestate *tuplestore);
 static void AfterTriggerFreeQuery(AfterTriggersQueryData *qs);
+static void release_or_prolong_tuplestore(Tuplestorestate *ts, bool prolonged);
 static SetConstraintState SetConstraintStateCreate(int numalloc);
 static SetConstraintState SetConstraintStateCopy(SetConstraintState origstate);
 static SetConstraintState SetConstraintStateAddItem(SetConstraintState state,
@@ -4737,6 +4744,45 @@ afterTriggerInvokeEvents(AfterTriggerEventList *events,
 }
 
 
+/*
+ * SetTransitionTablePreserved
+ *
+ * Prolong lifespan of transition tables corresponding specified relid and
+ * command type to the end of the outmost query instead of each nested query.
+ * This enables to use nested AFTER trigger's transition tables from outer
+ * query's triggers.  Currently, only immediate incremental view maintenance
+ * uses this.
+ */
+void
+SetTransitionTablePreserved(Oid relid, CmdType cmdType)
+{
+	AfterTriggersTableData *table;
+	AfterTriggersQueryData *qs;
+	bool		found = false;
+	ListCell   *lc;
+
+	/* Check state, like AfterTriggerSaveEvent. */
+	if (afterTriggers.query_depth < 0)
+		elog(ERROR, "SetTransitionTablePreserved() called outside of query");
+
+	qs = &afterTriggers.query_stack[afterTriggers.query_depth];
+
+	foreach(lc, qs->tables)
+	{
+		table = (AfterTriggersTableData *) lfirst(lc);
+		if (table->relid == relid && table->cmdType == cmdType &&
+			table->closed)
+		{
+			table->prolonged = true;
+			found = true;
+		}
+	}
+
+	if (!found)
+		elog(ERROR,"could not find table with OID %d and command type %d", relid, cmdType);
+}
+
+
 /*
  * GetAfterTriggersTableData
  *
@@ -4947,6 +4993,7 @@ AfterTriggerBeginXact(void)
 	 */
 	afterTriggers.firing_counter = (CommandId) 1;	/* mustn't be 0 */
 	afterTriggers.query_depth = -1;
+	afterTriggers.prolonged_tuplestores = NIL;
 
 	/*
 	 * Verify that there is no leftover state remaining.  If these assertions
@@ -5107,19 +5154,19 @@ AfterTriggerFreeQuery(AfterTriggersQueryData *qs)
 		ts = table->old_upd_tuplestore;
 		table->old_upd_tuplestore = NULL;
 		if (ts)
-			tuplestore_end(ts);
+			release_or_prolong_tuplestore(ts, table->prolonged);
 		ts = table->new_upd_tuplestore;
 		table->new_upd_tuplestore = NULL;
 		if (ts)
-			tuplestore_end(ts);
+			release_or_prolong_tuplestore(ts, table->prolonged);
 		ts = table->old_del_tuplestore;
 		table->old_del_tuplestore = NULL;
 		if (ts)
-			tuplestore_end(ts);
+			release_or_prolong_tuplestore(ts, table->prolonged);
 		ts = table->new_ins_tuplestore;
 		table->new_ins_tuplestore = NULL;
 		if (ts)
-			tuplestore_end(ts);
+			release_or_prolong_tuplestore(ts, table->prolonged);
 		if (table->storeslot)
 		{
 			TupleTableSlot *slot = table->storeslot;
@@ -5136,6 +5183,34 @@ AfterTriggerFreeQuery(AfterTriggersQueryData *qs)
 	 */
 	qs->tables = NIL;
 	list_free_deep(tables);
+
+	/* Release prolonged tuplestores at the end of the outmost query */
+	if (afterTriggers.query_depth == 0)
+	{
+		foreach(lc, afterTriggers.prolonged_tuplestores)
+		{
+			ts = (Tuplestorestate *) lfirst(lc);
+			if (ts)
+				tuplestore_end(ts);
+		}
+		afterTriggers.prolonged_tuplestores = NIL;
+	}
+}
+
+/*
+ * Release the tuplestore, or append it to the prolonged tuplestores list.
+ */
+static void
+release_or_prolong_tuplestore(Tuplestorestate *ts, bool prolonged)
+{
+	if (prolonged && afterTriggers.query_depth > 0)
+	{
+		MemoryContext oldcxt = MemoryContextSwitchTo(CurTransactionContext);
+		afterTriggers.prolonged_tuplestores = lappend(afterTriggers.prolonged_tuplestores, ts);
+		MemoryContextSwitchTo(oldcxt);
+	}
+	else
+		tuplestore_end(ts);
 }
 
 
diff --git a/src/include/commands/trigger.h b/src/include/commands/trigger.h
index 430e3ca7dd..48a21c4c51 100644
--- a/src/include/commands/trigger.h
+++ b/src/include/commands/trigger.h
@@ -265,6 +265,8 @@ extern void AfterTriggerEndSubXact(bool isCommit);
 extern void AfterTriggerSetState(ConstraintsSetStmt *stmt);
 extern bool AfterTriggerPendingOnRel(Oid relid);
 
+extern void SetTransitionTablePreserved(Oid relid, CmdType cmdType);
+
 
 /*
  * in utils/adt/ri_triggers.c
-- 
2.25.1


--Multipart=_Thu__1_Jun_2023_23_59_09_+0900_/G5+8nG46.f1T42K
Content-Type: text/x-diff;
 name="v28-0004-Add-Incremental-View-Maintenance-support-to-pg_d.patch"
Content-Disposition: attachment;
 filename="v28-0004-Add-Incremental-View-Maintenance-support-to-pg_d.patch"
Content-Transfer-Encoding: 7bit



^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread

* [PATCH v1] Minimal fix for WAIT FOR ... MODE 'standby_flush'
@ 2026-04-07 13:11 Andres Freund <andres@anarazel.de>
  0 siblings, 0 replies; 324+ messages in thread

From: Andres Freund @ 2026-04-07 13:11 UTC (permalink / raw)

The investigation into the negative test performance impact of 7e8aeb9e483
lead to discovering that there are a few issues with WAIT FOR.

This commit is just a minimal fix to prevent hangs in standby_flush mode, due
to WAIT FOR ... 'standby_flush' seeing a 0 LSN if a newly started walreceiver
does not receive any writes, because the stanby is already caught up.

There are several other issues and this is isn't necessarily the best fix. But
this way we get the hangs out of the way.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/zqbppucpmkeqecfy4s5kscnru4tbk6khp3ozqz6ad2zijz354k@w4bdf4z3wqoz
---
 src/backend/replication/walreceiver.c      | 2 --
 src/backend/replication/walreceiverfuncs.c | 1 +
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a437273cf9a..09fde92bfd7 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -242,8 +242,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 
 	SpinLockRelease(&walrcv->mutex);
 
-	pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
-
 	/* Arrange to clean up at walreceiver exit */
 	on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
 
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 4e03e721872..bd5d47be964 100644
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -321,6 +321,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
 		walrcv->flushedUpto = recptr;
 		walrcv->receivedTLI = tli;
 		walrcv->latestChunkStart = recptr;
+		pg_atomic_write_u64(&walrcv->writtenUpto, recptr);
 	}
 	walrcv->receiveStart = recptr;
 	walrcv->receiveStartTLI = tli;
-- 
2.53.0.1.gb2826b52eb


--ags3ltqh73mz7p2n--





^ permalink  raw  reply  [nested|flat] 324+ messages in thread