Is it worth adding ReplicationSlot active_pid to ReplicationSlotPersistentData?

From ec1a6b0bc6e9616c02acbf9e63a00746019bc83e Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Tue, 14 Dec 2021 13:31:26 +0000
Subject: [PATCH v1] Add LOG messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 src/backend/replication/slot.c | 39 ++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 90ba9b417d..63bf1140ec 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -318,6 +318,11 @@ ReplicationSlotCreate(const char *name, bool db_specific,
 	SpinLockRelease(&slot->mutex);
 	MyReplicationSlot = slot;
 
+	ereport(LOG,
+			(errmsg("replication slot \"%s\" becomes active",
+					NameStr(slot->data.name)),
+			 errdetail("The process with PID %d acquired it.", slot->active_pid)));
+
 	LWLockRelease(ReplicationSlotControlLock);
 
 	/*
@@ -457,6 +462,11 @@ retry:
 
 	/* We made this slot active, so it's ours now. */
 	MyReplicationSlot = s;
+
+	ereport(LOG,
+			(errmsg("replication slot \"%s\" becomes active",
+					NameStr(s->data.name)),
+			errdetail("The process with PID %d acquired it.", s->active_pid)));
 }
 
 /*
@@ -499,6 +509,10 @@ ReplicationSlotRelease(void)
 
 	if (slot->data.persistency == RS_PERSISTENT)
 	{
+		int	pid;
+
+		pid = slot->active_pid;
+
 		/*
 		 * Mark persistent slot inactive.  We're not freeing it, just
 		 * disconnecting, but wake up others that may be waiting for it.
@@ -506,6 +520,12 @@ ReplicationSlotRelease(void)
 		SpinLockAcquire(&slot->mutex);
 		slot->active_pid = 0;
 		SpinLockRelease(&slot->mutex);
+
+		ereport(LOG,
+				(errmsg("replication slot \"%s\" becomes inactive",
+						NameStr(slot->data.name)),
+				 errdetail("The process with PID %d released it.", pid)));
+
 		ConditionVariableBroadcast(&slot->active_cv);
 	}
 
@@ -594,6 +614,7 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 {
 	char		path[MAXPGPATH];
 	char		tmppath[MAXPGPATH];
+	int			pid;
 
 	/*
 	 * If some other backend ran this code concurrently with us, we might try
@@ -606,6 +627,8 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 	sprintf(path, "pg_replslot/%s", NameStr(slot->data.name));
 	sprintf(tmppath, "pg_replslot/%s.tmp", NameStr(slot->data.name));
 
+	pid = slot->active_pid;
+
 	/*
 	 * Rename the slot directory on disk, so that we'll no longer recognize
 	 * this as a valid slot.  Note that if this fails, we've got to mark the
@@ -636,6 +659,14 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 		slot->active_pid = 0;
 		SpinLockRelease(&slot->mutex);
 
+		ereport(LOG,
+				(errmsg("replication slot \"%s\" becomes inactive",
+						NameStr(slot->data.name)),
+				 errdetail("The process with PID %d released it.", pid)));
+
+		/* let's not emit the above message twice */
+		pid = -1;
+
 		/* wake up anyone waiting on this slot */
 		ConditionVariableBroadcast(&slot->active_cv);
 
@@ -645,6 +676,7 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 						path, tmppath)));
 	}
 
+
 	/*
 	 * The slot is definitely gone.  Lock out concurrent scans of the array
 	 * long enough to kill it.  It's OK to clear the active PID here without
@@ -658,6 +690,13 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 	slot->active_pid = 0;
 	slot->in_use = false;
 	LWLockRelease(ReplicationSlotControlLock);
+
+	if (pid > 0)
+		ereport(LOG,
+				(errmsg("replication slot \"%s\" becomes inactive",
+						NameStr(slot->data.name)),
+				 errdetail("The process with PID %d released it.", pid)));
+
 	ConditionVariableBroadcast(&slot->active_cv);
 
 	/*
-- 
2.25.1

From ddfe0a371599bc7bf9af6ba2e7dfad04673fb372 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Tue, 28 Dec 2021 06:53:16 +0000
Subject: [PATCH v2] Add LOG messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 src/backend/replication/slot.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 90ba9b417d..2fdb60927f 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -337,6 +337,13 @@ ReplicationSlotCreate(const char *name, bool db_specific,
 
 	/* Let everybody know we've modified this slot */
 	ConditionVariableBroadcast(&slot->active_cv);
+
+	ereport(LOG,
+			(errmsg("created %s %s replication slot \"%s\"",
+					(slot->data.persistency == RS_TEMPORARY ? "temporary" : "persistent"),
+					(SlotIsPhysical(slot) ? "physical" : "logical"),
+					NameStr(slot->data.name)),
+			 errhidestmt(true)));
 }
 
 /*
@@ -457,6 +464,13 @@ retry:
 
 	/* We made this slot active, so it's ours now. */
 	MyReplicationSlot = s;
+
+	ereport(LOG,
+			(errmsg("acquired %s %s replication slot \"%s\"",
+					(s->data.persistency == RS_TEMPORARY ? "temporary" : "persistent"),
+					(SlotIsPhysical(s) ? "physical" : "logical"),
+					NameStr(s->data.name)),
+			 errhidestmt(true)));
 }
 
 /*
@@ -516,6 +530,13 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	ereport(LOG,
+			(errmsg("released %s %s replication slot \"%s\"",
+					(slot->data.persistency == RS_TEMPORARY ? "temporary" : "persistent"),
+					(SlotIsPhysical(slot) ? "physical" : "logical"),
+					NameStr(slot->data.name)),
+			 errhidestmt(true)));
 }
 
 /*
@@ -700,6 +721,13 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 	 * a slot while we're still cleaning up the detritus of the old one.
 	 */
 	LWLockRelease(ReplicationSlotAllocationLock);
+
+	ereport(LOG,
+			(errmsg("dropped %s %s replication slot \"%s\"",
+					(slot->data.persistency == RS_TEMPORARY ? "temporary" : "persistent"),
+					(SlotIsPhysical(slot) ? "physical" : "logical"),
+					NameStr(slot->data.name)),
+			 errhidestmt(true)));
 }
 
 /*
-- 
2.25.1

From 46792e7b33c15afeda83769655e2512674c33269 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Sun, 9 Jan 2022 09:38:36 +0000
Subject: [PATCH v3] Add LOG messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 doc/src/sgml/config.sgml                      |  6 ++--
 .../replication/logical/logicalfuncs.c        |  4 +--
 src/backend/replication/slot.c                | 30 ++++++++++++++++---
 src/backend/replication/slotfuncs.c           | 10 +++----
 src/backend/replication/walsender.c           | 12 ++++----
 src/backend/storage/lmgr/proc.c               |  2 +-
 src/backend/tcop/postgres.c                   |  2 +-
 src/backend/utils/misc/guc.c                  |  2 +-
 src/include/replication/slot.h                |  4 +--
 9 files changed, 47 insertions(+), 25 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index afbb6c35e3..5f95fdffc8 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7284,9 +7284,9 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
+        Causes each replication command and related activity to be logged in
+        the server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is <literal>off</literal>.
         Only superusers can change this setting.
        </para>
       </listitem>
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 4f633888b4..ef19e48719 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -215,7 +215,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
 	else
 		end_of_wal = GetXLogReplayRecPtr(NULL);
 
-	ReplicationSlotAcquire(NameStr(*name), true);
+	ReplicationSlotAcquire(NameStr(*name), true, true);
 
 	PG_TRY();
 	{
@@ -331,7 +331,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
 		/* free context, call shutdown callback */
 		FreeDecodingContext(ctx);
 
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 		InvalidateSystemCaches();
 	}
 	PG_CATCH();
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index e5e0cf8768..fbb02bb036 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -337,6 +337,11 @@ ReplicationSlotCreate(const char *name, bool db_specific,
 
 	/* Let everybody know we've modified this slot */
 	ConditionVariableBroadcast(&slot->active_cv);
+
+	ereport(log_replication_commands ? LOG : DEBUG1,
+			(errmsg("created replication slot \"%s\"",
+					NameStr(slot->data.name)),
+			 errhidestmt(true)));
 }
 
 /*
@@ -377,7 +382,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
  * nowait is false, we sleep until the slot is released by the owning process.
  */
 void
-ReplicationSlotAcquire(const char *name, bool nowait)
+ReplicationSlotAcquire(const char *name, bool nowait, bool msg_ok)
 {
 	ReplicationSlot *s;
 	int			active_pid;
@@ -457,6 +462,12 @@ retry:
 
 	/* We made this slot active, so it's ours now. */
 	MyReplicationSlot = s;
+
+	if (msg_ok)
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				(errmsg("acquired replication slot \"%s\"",
+						NameStr(s->data.name)),
+				 errhidestmt(true)));
 }
 
 /*
@@ -466,7 +477,7 @@ retry:
  * Resources this slot requires will be preserved.
  */
 void
-ReplicationSlotRelease(void)
+ReplicationSlotRelease(bool msg_ok)
 {
 	ReplicationSlot *slot = MyReplicationSlot;
 
@@ -516,6 +527,12 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	if (msg_ok)
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				(errmsg("released replication slot \"%s\"",
+						NameStr(slot->data.name)),
+				 errhidestmt(true)));
 }
 
 /*
@@ -564,7 +581,7 @@ ReplicationSlotDrop(const char *name, bool nowait)
 {
 	Assert(MyReplicationSlot == NULL);
 
-	ReplicationSlotAcquire(name, nowait);
+	ReplicationSlotAcquire(name, nowait, false);
 
 	ReplicationSlotDropAcquired();
 }
@@ -700,6 +717,11 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 	 * a slot while we're still cleaning up the detritus of the old one.
 	 */
 	LWLockRelease(ReplicationSlotAllocationLock);
+
+	ereport(log_replication_commands ? LOG : DEBUG1,
+			(errmsg("dropped replication slot \"%s\"",
+					NameStr(slot->data.name)),
+			 errhidestmt(true)));
 }
 
 /*
@@ -1288,7 +1310,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlot *s, XLogRecPtr oldestLSN,
 			/* Make sure the invalidated state persists across server restart */
 			ReplicationSlotMarkDirty();
 			ReplicationSlotSave();
-			ReplicationSlotRelease();
+			ReplicationSlotRelease(true);
 
 			ereport(LOG,
 					(errmsg("invalidating slot \"%s\" because its restart_lsn %X/%X exceeds max_slot_wal_keep_size",
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index ae6316d908..6737c1bb78 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -99,7 +99,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
 	tuple = heap_form_tuple(tupdesc, values, nulls);
 	result = HeapTupleGetDatum(tuple);
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 
 	PG_RETURN_DATUM(result);
 }
@@ -201,7 +201,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
 	/* ok, slot is now fully created, mark it as persistent if needed */
 	if (!temporary)
 		ReplicationSlotPersist();
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 
 	PG_RETURN_DATUM(result);
 }
@@ -631,7 +631,7 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS)
 		moveto = Min(moveto, GetXLogReplayRecPtr(NULL));
 
 	/* Acquire the slot so we "own" it */
-	ReplicationSlotAcquire(NameStr(*slotname), true);
+	ReplicationSlotAcquire(NameStr(*slotname), true, true);
 
 	/* A slot whose restart_lsn has never been reserved cannot be advanced */
 	if (XLogRecPtrIsInvalid(MyReplicationSlot->data.restart_lsn))
@@ -674,7 +674,7 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS)
 	ReplicationSlotsComputeRequiredXmin(false);
 	ReplicationSlotsComputeRequiredLSN();
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(true);
 
 	/* Return the reached position. */
 	values[1] = LSNGetDatum(endlsn);
@@ -905,7 +905,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
 	tuple = heap_form_tuple(tupdesc, values, nulls);
 	result = HeapTupleGetDatum(tuple);
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 
 	PG_RETURN_DATUM(result);
 }
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 4cf95ce439..52ec13088e 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -304,7 +304,7 @@ WalSndErrorCleanup(void)
 		wal_segment_close(xlogreader);
 
 	if (MyReplicationSlot != NULL)
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 
 	ReplicationSlotCleanup();
 
@@ -695,7 +695,7 @@ StartReplication(StartReplicationCmd *cmd)
 
 	if (cmd->slotname)
 	{
-		ReplicationSlotAcquire(cmd->slotname, true);
+		ReplicationSlotAcquire(cmd->slotname, true, true);
 		if (SlotIsLogical(MyReplicationSlot))
 			ereport(ERROR,
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
@@ -841,7 +841,7 @@ StartReplication(StartReplicationCmd *cmd)
 	}
 
 	if (cmd->slotname)
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 
 	/*
 	 * Copy is finished now. Send a single-row result set indicating the next
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
 	do_tup_output(tstate, values, nulls);
 	end_tup_output(tstate);
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 }
 
 /*
@@ -1247,7 +1247,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 
 	Assert(!MyReplicationSlot);
 
-	ReplicationSlotAcquire(cmd->slotname, true);
+	ReplicationSlotAcquire(cmd->slotname, true, true);
 
 	if (XLogRecPtrIsInvalid(MyReplicationSlot->data.restart_lsn))
 		ereport(ERROR,
@@ -1316,7 +1316,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 	WalSndLoop(XLogSendLogical);
 
 	FreeDecodingContext(logical_decoding_ctx);
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(true);
 
 	replication_active = false;
 	if (got_STOPPING)
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index e306b04738..cb9fe4dc6f 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -832,7 +832,7 @@ ProcKill(int code, Datum arg)
 
 	/* Make sure active replication slots are released */
 	if (MyReplicationSlot != NULL)
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 
 	/* Also cleanup all the temporary slots. */
 	ReplicationSlotCleanup();
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index fda2e9360e..1bd192c03f 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -4265,7 +4265,7 @@ PostgresMain(const char *dbname, const char *username)
 		 * ensuring we'll correctly cleanup on FATAL errors as well.
 		 */
 		if (MyReplicationSlot != NULL)
-			ReplicationSlotRelease();
+			ReplicationSlotRelease(true);
 
 		/* We also want to cleanup temporary slots on error. */
 		ReplicationSlotCleanup();
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 6fc5cbc09a..90da7fa20e 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -1373,7 +1373,7 @@ static struct config_bool ConfigureNamesBool[] =
 	},
 	{
 		{"log_replication_commands", PGC_SUSET, LOGGING_WHAT,
-			gettext_noop("Logs each replication command."),
+			gettext_noop("Logs each replication command and related activity."),
 			NULL
 		},
 		&log_replication_commands,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index f833b1d6dc..af8c7b5baa 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -199,8 +199,8 @@ extern void ReplicationSlotCreate(const char *name, bool db_specific,
 extern void ReplicationSlotPersist(void);
 extern void ReplicationSlotDrop(const char *name, bool nowait);
 
-extern void ReplicationSlotAcquire(const char *name, bool nowait);
-extern void ReplicationSlotRelease(void);
+extern void ReplicationSlotAcquire(const char *name, bool nowait, bool msg_ok);
+extern void ReplicationSlotRelease(bool msg_ok);
 extern void ReplicationSlotCleanup(void);
 extern void ReplicationSlotSave(void);
 extern void ReplicationSlotMarkDirty(void);
-- 
2.25.1

From d6ee893d72931392d7fe01f2f2ce4b1340451f5d Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Sun, 27 Feb 2022 09:44:03 +0000
Subject: [PATCH v4] Add LOG messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 doc/src/sgml/config.sgml                      |  6 +--
 .../replication/logical/logicalfuncs.c        |  4 +-
 src/backend/replication/slot.c                | 38 ++++++++++++++-----
 src/backend/replication/slotfuncs.c           | 10 ++---
 src/backend/replication/walsender.c           | 12 +++---
 src/backend/tcop/postgres.c                   |  2 +-
 src/backend/utils/misc/guc.c                  |  2 +-
 src/include/replication/slot.h                |  4 +-
 8 files changed, 48 insertions(+), 30 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 7ed8c82a9d..b4e616bf52 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7322,9 +7322,9 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
+        Causes each replication command and related activity to be logged in
+        the server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is <literal>off</literal>.
         Only superusers can change this setting.
        </para>
       </listitem>
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 3bd770a3ba..87e73b37cc 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -216,7 +216,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
 	else
 		end_of_wal = GetXLogReplayRecPtr(NULL);
 
-	ReplicationSlotAcquire(NameStr(*name), true);
+	ReplicationSlotAcquire(NameStr(*name), true, true);
 
 	PG_TRY();
 	{
@@ -330,7 +330,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
 		/* free context, call shutdown callback */
 		FreeDecodingContext(ctx);
 
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 		InvalidateSystemCaches();
 	}
 	PG_CATCH();
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index caa6b29756..838e4019c1 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -183,7 +183,7 @@ ReplicationSlotShmemExit(int code, Datum arg)
 
 	/* Make sure active replication slots are released */
 	if (MyReplicationSlot != NULL)
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 
 	/* Also cleanup all the temporary slots. */
 	ReplicationSlotCleanup();
@@ -366,6 +366,10 @@ ReplicationSlotCreate(const char *name, bool db_specific,
 
 	/* Let everybody know we've modified this slot */
 	ConditionVariableBroadcast(&slot->active_cv);
+
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("created replication slot \"%s\"",
+					NameStr(slot->data.name))));
 }
 
 /*
@@ -406,7 +410,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
  * nowait is false, we sleep until the slot is released by the owning process.
  */
 void
-ReplicationSlotAcquire(const char *name, bool nowait)
+ReplicationSlotAcquire(const char *name, bool nowait, bool msg_ok)
 {
 	ReplicationSlot *s;
 	int			active_pid;
@@ -486,6 +490,11 @@ retry:
 
 	/* We made this slot active, so it's ours now. */
 	MyReplicationSlot = s;
+
+	if (msg_ok)
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("acquired replication slot \"%s\"",
+						NameStr(s->data.name))));
 }
 
 /*
@@ -495,7 +504,7 @@ retry:
  * Resources this slot requires will be preserved.
  */
 void
-ReplicationSlotRelease(void)
+ReplicationSlotRelease(bool msg_ok)
 {
 	ReplicationSlot *slot = MyReplicationSlot;
 
@@ -545,6 +554,11 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	if (msg_ok)
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("released replication slot \"%s\"",
+						NameStr(slot->data.name))));
 }
 
 /*
@@ -602,7 +616,7 @@ ReplicationSlotDrop(const char *name, bool nowait)
 {
 	Assert(MyReplicationSlot == NULL);
 
-	ReplicationSlotAcquire(name, nowait);
+	ReplicationSlotAcquire(name, nowait, false);
 
 	ReplicationSlotDropAcquired();
 }
@@ -634,7 +648,9 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 	char		tmppath[MAXPGPATH];
 
 	/* temp debugging aid to analyze 019_replslot_limit failures */
-	elog(DEBUG3, "replication slot drop: %s: begin", NameStr(slot->data.name));
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("replication slot drop: %s: begin",
+					NameStr(slot->data.name))));
 
 	/*
 	 * If some other backend ran this code concurrently with us, we might try
@@ -686,8 +702,9 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 						path, tmppath)));
 	}
 
-	elog(DEBUG3, "replication slot drop: %s: removed on-disk",
-		 NameStr(slot->data.name));
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("replication slot drop: %s: removed on-disk",
+					NameStr(slot->data.name))));
 
 	/*
 	 * The slot is definitely gone.  Lock out concurrent scans of the array
@@ -745,8 +762,9 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 	 */
 	LWLockRelease(ReplicationSlotAllocationLock);
 
-	elog(DEBUG3, "replication slot drop: %s: done",
-		 NameStr(slot->data.name));
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("replication slot drop: %s: done",
+					NameStr(slot->data.name))));
 }
 
 /*
@@ -1341,7 +1359,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlot *s, XLogRecPtr oldestLSN,
 			/* Make sure the invalidated state persists across server restart */
 			ReplicationSlotMarkDirty();
 			ReplicationSlotSave();
-			ReplicationSlotRelease();
+			ReplicationSlotRelease(true);
 
 			ereport(LOG,
 					(errmsg("invalidating slot \"%s\" because its restart_lsn %X/%X exceeds max_slot_wal_keep_size",
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 886899afd2..86572f9be9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -100,7 +100,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
 	tuple = heap_form_tuple(tupdesc, values, nulls);
 	result = HeapTupleGetDatum(tuple);
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 
 	PG_RETURN_DATUM(result);
 }
@@ -202,7 +202,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
 	/* ok, slot is now fully created, mark it as persistent if needed */
 	if (!temporary)
 		ReplicationSlotPersist();
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 
 	PG_RETURN_DATUM(result);
 }
@@ -630,7 +630,7 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS)
 		moveto = Min(moveto, GetXLogReplayRecPtr(NULL));
 
 	/* Acquire the slot so we "own" it */
-	ReplicationSlotAcquire(NameStr(*slotname), true);
+	ReplicationSlotAcquire(NameStr(*slotname), true, true);
 
 	/* A slot whose restart_lsn has never been reserved cannot be advanced */
 	if (XLogRecPtrIsInvalid(MyReplicationSlot->data.restart_lsn))
@@ -673,7 +673,7 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS)
 	ReplicationSlotsComputeRequiredXmin(false);
 	ReplicationSlotsComputeRequiredLSN();
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(true);
 
 	/* Return the reached position. */
 	values[1] = LSNGetDatum(endlsn);
@@ -904,7 +904,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
 	tuple = heap_form_tuple(tupdesc, values, nulls);
 	result = HeapTupleGetDatum(tuple);
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 
 	PG_RETURN_DATUM(result);
 }
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 5a718b1fe9..ebd036a8ab 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -305,7 +305,7 @@ WalSndErrorCleanup(void)
 		wal_segment_close(xlogreader);
 
 	if (MyReplicationSlot != NULL)
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 
 	ReplicationSlotCleanup();
 
@@ -696,7 +696,7 @@ StartReplication(StartReplicationCmd *cmd)
 
 	if (cmd->slotname)
 	{
-		ReplicationSlotAcquire(cmd->slotname, true);
+		ReplicationSlotAcquire(cmd->slotname, true, true);
 		if (SlotIsLogical(MyReplicationSlot))
 			ereport(ERROR,
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
@@ -842,7 +842,7 @@ StartReplication(StartReplicationCmd *cmd)
 	}
 
 	if (cmd->slotname)
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 
 	/*
 	 * Copy is finished now. Send a single-row result set indicating the next
@@ -1221,7 +1221,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
 	do_tup_output(tstate, values, nulls);
 	end_tup_output(tstate);
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 }
 
 /*
@@ -1248,7 +1248,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 
 	Assert(!MyReplicationSlot);
 
-	ReplicationSlotAcquire(cmd->slotname, true);
+	ReplicationSlotAcquire(cmd->slotname, true, true);
 
 	if (XLogRecPtrIsInvalid(MyReplicationSlot->data.restart_lsn))
 		ereport(ERROR,
@@ -1317,7 +1317,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 	WalSndLoop(XLogSendLogical);
 
 	FreeDecodingContext(logical_decoding_ctx);
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(true);
 
 	replication_active = false;
 	if (got_STOPPING)
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 3c7d08209f..d159982df7 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -4273,7 +4273,7 @@ PostgresMain(const char *dbname, const char *username)
 		 * callback ensuring correct cleanup on FATAL errors.
 		 */
 		if (MyReplicationSlot != NULL)
-			ReplicationSlotRelease();
+			ReplicationSlotRelease(true);
 
 		/* We also want to cleanup temporary slots on error. */
 		ReplicationSlotCleanup();
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 1e3650184b..3480890f0e 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -1378,7 +1378,7 @@ static struct config_bool ConfigureNamesBool[] =
 	},
 	{
 		{"log_replication_commands", PGC_SUSET, LOGGING_WHAT,
-			gettext_noop("Logs each replication command."),
+			gettext_noop("Logs each replication command and related activity."),
 			NULL
 		},
 		&log_replication_commands,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 24b30210c3..2ec6032cbf 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -199,8 +199,8 @@ extern void ReplicationSlotCreate(const char *name, bool db_specific,
 extern void ReplicationSlotPersist(void);
 extern void ReplicationSlotDrop(const char *name, bool nowait);
 
-extern void ReplicationSlotAcquire(const char *name, bool nowait);
-extern void ReplicationSlotRelease(void);
+extern void ReplicationSlotAcquire(const char *name, bool nowait, bool msg_ok);
+extern void ReplicationSlotRelease(bool msg_ok);
 extern void ReplicationSlotCleanup(void);
 extern void ReplicationSlotSave(void);
 extern void ReplicationSlotMarkDirty(void);
-- 
2.25.1

From 635bdfb7ac1d0fe57a8a0949290d34e5d2a35427 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Fri, 29 Apr 2022 09:58:33 +0000
Subject: [PATCH v5] Add LOG messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 doc/src/sgml/config.sgml                      |  7 ++--
 .../replication/logical/logicalfuncs.c        |  4 +-
 src/backend/replication/slot.c                | 38 ++++++++++++++-----
 src/backend/replication/slotfuncs.c           | 10 ++---
 src/backend/replication/walsender.c           | 12 +++---
 src/backend/tcop/postgres.c                   |  2 +-
 src/backend/utils/misc/guc.c                  |  2 +-
 src/include/replication/slot.h                |  4 +-
 8 files changed, 49 insertions(+), 30 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 03986946a8..b6b7b4d838 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7461,9 +7461,10 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
+        Causes each replication command and related activity to be logged in
+        the server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>.
         Only superusers and users with the appropriate <literal>SET</literal>
         privilege can change this setting.
        </para>
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 6058d36e0d..11e66a5821 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -201,7 +201,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
 	else
 		end_of_wal = GetXLogReplayRecPtr(NULL);
 
-	ReplicationSlotAcquire(NameStr(*name), true);
+	ReplicationSlotAcquire(NameStr(*name), true, true);
 
 	PG_TRY();
 	{
@@ -315,7 +315,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
 		/* free context, call shutdown callback */
 		FreeDecodingContext(ctx);
 
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 		InvalidateSystemCaches();
 	}
 	PG_CATCH();
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 5c778f5333..d9246e2ebc 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -183,7 +183,7 @@ ReplicationSlotShmemExit(int code, Datum arg)
 
 	/* Make sure active replication slots are released */
 	if (MyReplicationSlot != NULL)
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 
 	/* Also cleanup all the temporary slots. */
 	ReplicationSlotCleanup();
@@ -366,6 +366,10 @@ ReplicationSlotCreate(const char *name, bool db_specific,
 
 	/* Let everybody know we've modified this slot */
 	ConditionVariableBroadcast(&slot->active_cv);
+
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("created replication slot \"%s\"",
+					NameStr(slot->data.name))));
 }
 
 /*
@@ -422,7 +426,7 @@ ReplicationSlotIndex(ReplicationSlot *slot)
  * nowait is false, we sleep until the slot is released by the owning process.
  */
 void
-ReplicationSlotAcquire(const char *name, bool nowait)
+ReplicationSlotAcquire(const char *name, bool nowait, bool msg_ok)
 {
 	ReplicationSlot *s;
 	int			active_pid;
@@ -503,6 +507,11 @@ retry:
 	/* We made this slot active, so it's ours now. */
 	MyReplicationSlot = s;
 
+	if (msg_ok)
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("acquired replication slot \"%s\"",
+						NameStr(s->data.name))));
+
 	/*
 	 * The call to pgstat_acquire_replslot() protects against stats for
 	 * a different slot, from before a restart or such, being present during
@@ -519,7 +528,7 @@ retry:
  * Resources this slot requires will be preserved.
  */
 void
-ReplicationSlotRelease(void)
+ReplicationSlotRelease(bool msg_ok)
 {
 	ReplicationSlot *slot = MyReplicationSlot;
 
@@ -569,6 +578,11 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	if (msg_ok)
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("released replication slot \"%s\"",
+						NameStr(slot->data.name))));
 }
 
 /*
@@ -626,7 +640,7 @@ ReplicationSlotDrop(const char *name, bool nowait)
 {
 	Assert(MyReplicationSlot == NULL);
 
-	ReplicationSlotAcquire(name, nowait);
+	ReplicationSlotAcquire(name, nowait, false);
 
 	ReplicationSlotDropAcquired();
 }
@@ -658,7 +672,9 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 	char		tmppath[MAXPGPATH];
 
 	/* temp debugging aid to analyze 019_replslot_limit failures */
-	elog(DEBUG3, "replication slot drop: %s: begin", NameStr(slot->data.name));
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("replication slot drop: %s: begin",
+					NameStr(slot->data.name))));
 
 	/*
 	 * If some other backend ran this code concurrently with us, we might try
@@ -710,8 +726,9 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 						path, tmppath)));
 	}
 
-	elog(DEBUG3, "replication slot drop: %s: removed on-disk",
-		 NameStr(slot->data.name));
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("replication slot drop: %s: removed on-disk",
+					NameStr(slot->data.name))));
 
 	/*
 	 * The slot is definitely gone.  Lock out concurrent scans of the array
@@ -768,8 +785,9 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 	 */
 	LWLockRelease(ReplicationSlotAllocationLock);
 
-	elog(DEBUG3, "replication slot drop: %s: done",
-		 NameStr(slot->data.name));
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("replication slot drop: %s: done",
+					NameStr(slot->data.name))));
 }
 
 /*
@@ -1364,7 +1382,7 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlot *s, XLogRecPtr oldestLSN,
 			/* Make sure the invalidated state persists across server restart */
 			ReplicationSlotMarkDirty();
 			ReplicationSlotSave();
-			ReplicationSlotRelease();
+			ReplicationSlotRelease(true);
 
 			ereport(LOG,
 					(errmsg("invalidating slot \"%s\" because its restart_lsn %X/%X exceeds max_slot_wal_keep_size",
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index ca945994ef..368ab444b4 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -100,7 +100,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
 	tuple = heap_form_tuple(tupdesc, values, nulls);
 	result = HeapTupleGetDatum(tuple);
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 
 	PG_RETURN_DATUM(result);
 }
@@ -202,7 +202,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
 	/* ok, slot is now fully created, mark it as persistent if needed */
 	if (!temporary)
 		ReplicationSlotPersist();
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 
 	PG_RETURN_DATUM(result);
 }
@@ -605,7 +605,7 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS)
 		moveto = Min(moveto, GetXLogReplayRecPtr(NULL));
 
 	/* Acquire the slot so we "own" it */
-	ReplicationSlotAcquire(NameStr(*slotname), true);
+	ReplicationSlotAcquire(NameStr(*slotname), true, true);
 
 	/* A slot whose restart_lsn has never been reserved cannot be advanced */
 	if (XLogRecPtrIsInvalid(MyReplicationSlot->data.restart_lsn))
@@ -648,7 +648,7 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS)
 	ReplicationSlotsComputeRequiredXmin(false);
 	ReplicationSlotsComputeRequiredLSN();
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(true);
 
 	/* Return the reached position. */
 	values[1] = LSNGetDatum(endlsn);
@@ -879,7 +879,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
 	tuple = heap_form_tuple(tupdesc, values, nulls);
 	result = HeapTupleGetDatum(tuple);
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 
 	PG_RETURN_DATUM(result);
 }
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 63a818140b..e4879a43f5 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -322,7 +322,7 @@ WalSndErrorCleanup(void)
 		wal_segment_close(xlogreader);
 
 	if (MyReplicationSlot != NULL)
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 
 	ReplicationSlotCleanup();
 
@@ -713,7 +713,7 @@ StartReplication(StartReplicationCmd *cmd)
 
 	if (cmd->slotname)
 	{
-		ReplicationSlotAcquire(cmd->slotname, true);
+		ReplicationSlotAcquire(cmd->slotname, true, true);
 		if (SlotIsLogical(MyReplicationSlot))
 			ereport(ERROR,
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
@@ -859,7 +859,7 @@ StartReplication(StartReplicationCmd *cmd)
 	}
 
 	if (cmd->slotname)
-		ReplicationSlotRelease();
+		ReplicationSlotRelease(true);
 
 	/*
 	 * Copy is finished now. Send a single-row result set indicating the next
@@ -1237,7 +1237,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
 	do_tup_output(tstate, values, nulls);
 	end_tup_output(tstate);
 
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(false);
 }
 
 /*
@@ -1264,7 +1264,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 
 	Assert(!MyReplicationSlot);
 
-	ReplicationSlotAcquire(cmd->slotname, true);
+	ReplicationSlotAcquire(cmd->slotname, true, true);
 
 	if (XLogRecPtrIsInvalid(MyReplicationSlot->data.restart_lsn))
 		ereport(ERROR,
@@ -1333,7 +1333,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 	WalSndLoop(XLogSendLogical);
 
 	FreeDecodingContext(logical_decoding_ctx);
-	ReplicationSlotRelease();
+	ReplicationSlotRelease(true);
 
 	replication_active = false;
 	if (got_STOPPING)
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 304cce135a..144d081715 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -4295,7 +4295,7 @@ PostgresMain(const char *dbname, const char *username)
 		 * callback ensuring correct cleanup on FATAL errors.
 		 */
 		if (MyReplicationSlot != NULL)
-			ReplicationSlotRelease();
+			ReplicationSlotRelease(true);
 
 		/* We also want to cleanup temporary slots on error. */
 		ReplicationSlotCleanup();
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 8e9b71375c..50dfd5cd3c 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -1424,7 +1424,7 @@ static struct config_bool ConfigureNamesBool[] =
 	},
 	{
 		{"log_replication_commands", PGC_SUSET, LOGGING_WHAT,
-			gettext_noop("Logs each replication command."),
+			gettext_noop("Logs each replication command and related activity."),
 			NULL
 		},
 		&log_replication_commands,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1ee63c4cf4..70871c6785 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -199,8 +199,8 @@ extern void ReplicationSlotCreate(const char *name, bool db_specific,
 extern void ReplicationSlotPersist(void);
 extern void ReplicationSlotDrop(const char *name, bool nowait);
 
-extern void ReplicationSlotAcquire(const char *name, bool nowait);
-extern void ReplicationSlotRelease(void);
+extern void ReplicationSlotAcquire(const char *name, bool nowait, bool msg_ok);
+extern void ReplicationSlotRelease(bool msg_ok);
 extern void ReplicationSlotCleanup(void);
 extern void ReplicationSlotSave(void);
 extern void ReplicationSlotMarkDirty(void);
-- 
2.25.1

From c57cfd8dd27eaf9e0c17c47769cb24b8ab961116 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Mon, 25 Jul 2022 12:51:26 +0000
Subject: [PATCH v6] Add LOG messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 doc/src/sgml/config.sgml            |  7 +++---
 src/backend/replication/slot.c      | 21 ++++++++++++++++
 src/backend/replication/walsender.c | 39 +++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index e2d728e0c4..8bf3c2ab53 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7461,9 +7461,10 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
+        Causes each replication command and related activity to be logged in
+        the server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>.
         Only superusers and users with the appropriate <literal>SET</literal>
         privilege can change this setting.
        </para>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 850b74936f..43563bec7e 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -179,8 +179,29 @@ ReplicationSlotShmemExit(int code, Datum arg)
 {
 	/* Make sure active replication slots are released */
 	if (MyReplicationSlot != NULL)
+	{
+		bool is_physical;
+		char slotname[NAMEDATALEN] = {0};
+
+		is_physical = SlotIsPhysical(MyReplicationSlot);
+		strcpy(slotname, NameStr(MyReplicationSlot->data.name));
+
 		ReplicationSlotRelease();
 
+		if (is_physical)
+		{
+			ereport(log_replication_commands ? LOG : DEBUG3,
+					(errmsg("released physical replication slot \"%s\"",
+							slotname)));
+		}
+		else
+		{
+			ereport(log_replication_commands ? LOG : DEBUG3,
+					(errmsg("released logical replication slot \"%s\"",
+							slotname)));
+		}
+	}
+
 	/* Also cleanup all the temporary slots. */
 	ReplicationSlotCleanup();
 }
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 3a86786cc3..ebd34316e2 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -322,8 +322,29 @@ WalSndErrorCleanup(void)
 		wal_segment_close(xlogreader);
 
 	if (MyReplicationSlot != NULL)
+	{
+		bool is_physical;
+		char slotname[NAMEDATALEN] = {0};
+
+		is_physical = SlotIsPhysical(MyReplicationSlot);
+		strcpy(slotname, NameStr(MyReplicationSlot->data.name));
+
 		ReplicationSlotRelease();
 
+		if (is_physical)
+		{
+			ereport(log_replication_commands ? LOG : DEBUG3,
+					(errmsg("released physical replication slot \"%s\"",
+							slotname)));
+		}
+		else
+		{
+			ereport(log_replication_commands ? LOG : DEBUG3,
+					(errmsg("released logical replication slot \"%s\"",
+							slotname)));
+		}
+	}
+
 	ReplicationSlotCleanup();
 
 	replication_active = false;
@@ -704,6 +725,10 @@ StartReplication(StartReplicationCmd *cmd)
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 					 errmsg("cannot use a logical replication slot for physical replication")));
 
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("acquired physical replication slot \"%s\"",
+						cmd->slotname)));
+
 		/*
 		 * We don't need to verify the slot's restart_lsn here; instead we
 		 * rely on the caller requesting the starting point to use.  If the
@@ -844,8 +869,14 @@ StartReplication(StartReplicationCmd *cmd)
 	}
 
 	if (cmd->slotname)
+	{
 		ReplicationSlotRelease();
 
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("released physical replication slot \"%s\"",
+						cmd->slotname)));
+	}
+
 	/*
 	 * Copy is finished now. Send a single-row result set indicating the next
 	 * timeline.
@@ -1256,6 +1287,10 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 						cmd->slotname),
 				 errdetail("This slot has been invalidated because it exceeded the maximum reserved size.")));
 
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("acquired logical replication slot \"%s\"",
+					cmd->slotname)));
+
 	/*
 	 * Force a disconnect, so that the decoding code doesn't need to care
 	 * about an eventual switch from running in recovery, to running in a
@@ -1318,6 +1353,10 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 	FreeDecodingContext(logical_decoding_ctx);
 	ReplicationSlotRelease();
 
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("released logical replication slot \"%s\"",
+					cmd->slotname)));
+
 	replication_active = false;
 	if (got_STOPPING)
 		proc_exit(0);
-- 
2.34.1

From fc53b36e62c76bb29ad201842a7a6c1bdb94b6da Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Thu, 15 Sep 2022 05:05:22 +0000
Subject: [PATCH v7] Add LOG messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 doc/src/sgml/config.sgml            |  7 +++---
 src/backend/replication/slot.c      | 17 ++++++++++++++
 src/backend/replication/walsender.c | 35 +++++++++++++++++++++++++++++
 src/backend/utils/misc/guc_tables.c |  2 +-
 4 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 700914684d..55976b3df8 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7482,9 +7482,10 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
+        Causes each replication command and related activity to be logged in
+        the server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>.
         Only superusers and users with the appropriate <literal>SET</literal>
         privilege can change this setting.
        </para>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 8fec1cb4a5..9814fc87de 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -180,8 +180,25 @@ ReplicationSlotShmemExit(int code, Datum arg)
 {
 	/* Make sure active replication slots are released */
 	if (MyReplicationSlot != NULL)
+	{
+		bool is_physical;
+		char slotname[NAMEDATALEN] = {0};
+
+		is_physical = SlotIsPhysical(MyReplicationSlot);
+		strcpy(slotname, NameStr(MyReplicationSlot->data.name));
+
 		ReplicationSlotRelease();
 
+		if (is_physical)
+			ereport(log_replication_commands ? LOG : DEBUG3,
+					(errmsg("released physical replication slot \"%s\"",
+							slotname)));
+		else
+			ereport(log_replication_commands ? LOG : DEBUG3,
+					(errmsg("released logical replication slot \"%s\"",
+							slotname)));
+	}
+
 	/* Also cleanup all the temporary slots. */
 	ReplicationSlotCleanup();
 }
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 724010dbd9..3daaea362a 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -322,8 +322,25 @@ WalSndErrorCleanup(void)
 		wal_segment_close(xlogreader);
 
 	if (MyReplicationSlot != NULL)
+	{
+		bool is_physical;
+		char slotname[NAMEDATALEN] = {0};
+
+		is_physical = SlotIsPhysical(MyReplicationSlot);
+		strcpy(slotname, NameStr(MyReplicationSlot->data.name));
+
 		ReplicationSlotRelease();
 
+		if (is_physical)
+			ereport(log_replication_commands ? LOG : DEBUG3,
+					(errmsg("released physical replication slot \"%s\"",
+							slotname)));
+		else
+			ereport(log_replication_commands ? LOG : DEBUG3,
+					(errmsg("released logical replication slot \"%s\"",
+							slotname)));
+	}
+
 	ReplicationSlotCleanup();
 
 	replication_active = false;
@@ -704,6 +721,10 @@ StartReplication(StartReplicationCmd *cmd)
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 					 errmsg("cannot use a logical replication slot for physical replication")));
 
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("acquired physical replication slot \"%s\"",
+						cmd->slotname)));
+
 		/*
 		 * We don't need to verify the slot's restart_lsn here; instead we
 		 * rely on the caller requesting the starting point to use.  If the
@@ -844,8 +865,14 @@ StartReplication(StartReplicationCmd *cmd)
 	}
 
 	if (cmd->slotname)
+	{
 		ReplicationSlotRelease();
 
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("released physical replication slot \"%s\"",
+						cmd->slotname)));
+	}
+
 	/*
 	 * Copy is finished now. Send a single-row result set indicating the next
 	 * timeline.
@@ -1256,6 +1283,10 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 						cmd->slotname),
 				 errdetail("This slot has been invalidated because it exceeded the maximum reserved size.")));
 
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("acquired logical replication slot \"%s\"",
+					cmd->slotname)));
+
 	/*
 	 * Force a disconnect, so that the decoding code doesn't need to care
 	 * about an eventual switch from running in recovery, to running in a
@@ -1318,6 +1349,10 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 	FreeDecodingContext(logical_decoding_ctx);
 	ReplicationSlotRelease();
 
+	ereport(log_replication_commands ? LOG : DEBUG3,
+			(errmsg("released logical replication slot \"%s\"",
+					cmd->slotname)));
+
 	replication_active = false;
 	if (got_STOPPING)
 		proc_exit(0);
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 550e95056c..da1f90b4fa 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -1177,7 +1177,7 @@ struct config_bool ConfigureNamesBool[] =
 	},
 	{
 		{"log_replication_commands", PGC_SUSET, LOGGING_WHAT,
-			gettext_noop("Logs each replication command."),
+			gettext_noop("Logs each replication command and related activity."),
 			NULL
 		},
 		&log_replication_commands,
-- 
2.34.1

From b0824cbe21d02d6826aead6cc7cf50c955160626 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Thu, 23 Mar 2023 17:21:12 +0000
Subject: [PATCH v8] Add LOG messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 doc/src/sgml/config.sgml            |  7 +++--
 src/backend/replication/slot.c      | 45 +++++++++++++++++++++++++++++
 src/backend/replication/walsender.c | 17 +++++++++++
 src/backend/utils/misc/guc_tables.c |  2 +-
 src/include/replication/slot.h      |  2 ++
 5 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 481f93cea1..f9b0d3c9a9 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7593,9 +7593,10 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
+        Causes each replication command and related activity to be logged in
+        the server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>.
         Only superusers and users with the appropriate <literal>SET</literal>
         privilege can change this setting.
        </para>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 2293c0c6fc..4dba028ab9 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -180,7 +180,16 @@ ReplicationSlotShmemExit(int code, Datum arg)
 {
 	/* Make sure active replication slots are released */
 	if (MyReplicationSlot != NULL)
+	{
+		bool is_physical;
+		char *slotname;
+
+		is_physical = SlotIsPhysical(MyReplicationSlot);
+		slotname = pstrdup(NameStr(MyReplicationSlot->data.name));
 		ReplicationSlotRelease();
+		LogReplicationSlotReleased(is_physical, slotname);
+		pfree(slotname);
+	}
 
 	/* Also cleanup all the temporary slots. */
 	ReplicationSlotCleanup();
@@ -596,6 +605,42 @@ ReplicationSlotRelease(void)
 	LWLockRelease(ProcArrayLock);
 }
 
+/*
+ * Helper function to log a message after replication slot acquisition.
+ */
+void
+LogReplicationSlotAquired(bool is_physical, char *slotname)
+{
+	Assert(MyReplicationSlot != NULL);
+
+	if (is_physical)
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("acquired physical replication slot \"%s\"",
+						slotname)));
+	else
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("acquired logical replication slot \"%s\"",
+						slotname)));
+}
+
+/*
+ * Helper function to log a message after replication slot release.
+ */
+void
+LogReplicationSlotReleased(bool is_physical, char *slotname)
+{
+	Assert(MyReplicationSlot == NULL);
+
+	if (is_physical)
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("released physical replication slot \"%s\"",
+						slotname)));
+	else
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				(errmsg("released logical replication slot \"%s\"",
+						slotname)));
+}
+
 /*
  * Cleanup all temporary slots created in current session.
  */
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 75e8363e24..38d25ed3c8 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -322,7 +322,16 @@ WalSndErrorCleanup(void)
 		wal_segment_close(xlogreader);
 
 	if (MyReplicationSlot != NULL)
+	{
+		bool is_physical;
+		char *slotname;
+
+		is_physical = SlotIsPhysical(MyReplicationSlot);
+		slotname = pstrdup(NameStr(MyReplicationSlot->data.name));
 		ReplicationSlotRelease();
+		LogReplicationSlotReleased(is_physical, slotname);
+		pfree(slotname);
+	}
 
 	ReplicationSlotCleanup();
 
@@ -703,6 +712,8 @@ StartReplication(StartReplicationCmd *cmd)
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 					 errmsg("cannot use a logical replication slot for physical replication")));
 
+		LogReplicationSlotAquired(true, cmd->slotname);
+
 		/*
 		 * We don't need to verify the slot's restart_lsn here; instead we
 		 * rely on the caller requesting the starting point to use.  If the
@@ -843,7 +854,10 @@ StartReplication(StartReplicationCmd *cmd)
 	}
 
 	if (cmd->slotname)
+	{
 		ReplicationSlotRelease();
+		LogReplicationSlotReleased(true, cmd->slotname);
+	}
 
 	/*
 	 * Copy is finished now. Send a single-row result set indicating the next
@@ -1260,6 +1274,8 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 						cmd->slotname),
 				 errdetail("This slot has been invalidated because it exceeded the maximum reserved size.")));
 
+	LogReplicationSlotAquired(false, cmd->slotname);
+
 	/*
 	 * Force a disconnect, so that the decoding code doesn't need to care
 	 * about an eventual switch from running in recovery, to running in a
@@ -1321,6 +1337,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 
 	FreeDecodingContext(logical_decoding_ctx);
 	ReplicationSlotRelease();
+	LogReplicationSlotReleased(false, cmd->slotname);
 
 	replication_active = false;
 	if (got_STOPPING)
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 1c0583fe26..ea41ccc7e2 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -1203,7 +1203,7 @@ struct config_bool ConfigureNamesBool[] =
 	},
 	{
 		{"log_replication_commands", PGC_SUSET, LOGGING_WHAT,
-			gettext_noop("Logs each replication command."),
+			gettext_noop("Logs each replication command and related activity."),
 			NULL
 		},
 		&log_replication_commands,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 8872c80cdf..147e4d4371 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -202,6 +202,8 @@ extern void ReplicationSlotDrop(const char *name, bool nowait);
 
 extern void ReplicationSlotAcquire(const char *name, bool nowait);
 extern void ReplicationSlotRelease(void);
+extern void LogReplicationSlotAquired(bool is_physical, char *slotname);
+extern void LogReplicationSlotReleased(bool is_physical, char *slotname);
 extern void ReplicationSlotCleanup(void);
 extern void ReplicationSlotSave(void);
 extern void ReplicationSlotMarkDirty(void);
-- 
2.34.1

From 44d6a8528e22e5882319d1308c74946b95922bfd Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Fri, 24 Mar 2023 03:23:15 +0000
Subject: [PATCH v9] Add LOG messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 doc/src/sgml/config.sgml            |  7 +++--
 src/backend/replication/slot.c      | 49 +++++++++++++++++++++++++++++
 src/backend/replication/walsender.c | 15 +++++++++
 src/backend/utils/misc/guc_tables.c |  2 +-
 src/include/replication/slot.h      |  2 ++
 5 files changed, 71 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 481f93cea1..f9b0d3c9a9 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7593,9 +7593,10 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
+        Causes each replication command and related activity to be logged in
+        the server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>.
         Only superusers and users with the appropriate <literal>SET</literal>
         privilege can change this setting.
        </para>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 2293c0c6fc..3e363eaad8 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -180,7 +180,14 @@ ReplicationSlotShmemExit(int code, Datum arg)
 {
 	/* Make sure active replication slots are released */
 	if (MyReplicationSlot != NULL)
+	{
+		char *slotname;
+
+		slotname = pstrdup(NameStr(MyReplicationSlot->data.name));
 		ReplicationSlotRelease();
+		LogReplicationSlotRelease(SlotIsPhysical(MyReplicationSlot), slotname);
+		pfree(slotname);
+	}
 
 	/* Also cleanup all the temporary slots. */
 	ReplicationSlotCleanup();
@@ -445,6 +452,9 @@ ReplicationSlotName(int index, Name name)
  *
  * An error is raised if nowait is true and the slot is currently in use. If
  * nowait is false, we sleep until the slot is released by the owning process.
+ *
+ * Note: use LogReplicationSlotAcquire() if needed, to log a message after
+ * acquiring the replication slot.
  */
 void
 ReplicationSlotAcquire(const char *name, bool nowait)
@@ -542,6 +552,9 @@ retry:
  *
  * This or another backend can re-acquire the slot later.
  * Resources this slot requires will be preserved.
+ *
+ * Note: use LogReplicationSlotRelease() if needed, to log a message after
+ * releasing the replication slot.
  */
 void
 ReplicationSlotRelease(void)
@@ -596,6 +609,42 @@ ReplicationSlotRelease(void)
 	LWLockRelease(ProcArrayLock);
 }
 
+/*
+ * Helper function to log a message after replication slot acquisition.
+ */
+void
+LogReplicationSlotAcquire(bool is_physical, const char *slotname)
+{
+	Assert(MyReplicationSlot != NULL);
+
+	if (is_physical)
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				errmsg("physical replication slot \"%s\" is acquired",
+					   slotname));
+	else
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				errmsg("logical replication slot \"%s\" is acquired",
+						slotname));
+}
+
+/*
+ * Helper function to log a message after replication slot release.
+ */
+void
+LogReplicationSlotRelease(bool is_physical, const char *slotname)
+{
+	Assert(MyReplicationSlot == NULL);
+
+	if (is_physical)
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				errmsg("physical replication slot \"%s\" is released",
+						slotname));
+	else
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				errmsg("logical replication slot \"%s\" is released",
+						slotname));
+}
+
 /*
  * Cleanup all temporary slots created in current session.
  */
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 75e8363e24..97ecb0b7d5 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -322,7 +322,14 @@ WalSndErrorCleanup(void)
 		wal_segment_close(xlogreader);
 
 	if (MyReplicationSlot != NULL)
+	{
+		char *slotname;
+
+		slotname = pstrdup(NameStr(MyReplicationSlot->data.name));
 		ReplicationSlotRelease();
+		LogReplicationSlotRelease(SlotIsPhysical(MyReplicationSlot), slotname);
+		pfree(slotname);
+	}
 
 	ReplicationSlotCleanup();
 
@@ -703,6 +710,8 @@ StartReplication(StartReplicationCmd *cmd)
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 					 errmsg("cannot use a logical replication slot for physical replication")));
 
+		LogReplicationSlotAcquire(true, cmd->slotname);
+
 		/*
 		 * We don't need to verify the slot's restart_lsn here; instead we
 		 * rely on the caller requesting the starting point to use.  If the
@@ -843,7 +852,10 @@ StartReplication(StartReplicationCmd *cmd)
 	}
 
 	if (cmd->slotname)
+	{
 		ReplicationSlotRelease();
+		LogReplicationSlotRelease(true, cmd->slotname);
+	}
 
 	/*
 	 * Copy is finished now. Send a single-row result set indicating the next
@@ -1260,6 +1272,8 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 						cmd->slotname),
 				 errdetail("This slot has been invalidated because it exceeded the maximum reserved size.")));
 
+	LogReplicationSlotAcquire(false, cmd->slotname);
+
 	/*
 	 * Force a disconnect, so that the decoding code doesn't need to care
 	 * about an eventual switch from running in recovery, to running in a
@@ -1321,6 +1335,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 
 	FreeDecodingContext(logical_decoding_ctx);
 	ReplicationSlotRelease();
+	LogReplicationSlotRelease(false, cmd->slotname);
 
 	replication_active = false;
 	if (got_STOPPING)
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 1c0583fe26..ea41ccc7e2 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -1203,7 +1203,7 @@ struct config_bool ConfigureNamesBool[] =
 	},
 	{
 		{"log_replication_commands", PGC_SUSET, LOGGING_WHAT,
-			gettext_noop("Logs each replication command."),
+			gettext_noop("Logs each replication command and related activity."),
 			NULL
 		},
 		&log_replication_commands,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 8872c80cdf..d5faf89368 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -202,6 +202,8 @@ extern void ReplicationSlotDrop(const char *name, bool nowait);
 
 extern void ReplicationSlotAcquire(const char *name, bool nowait);
 extern void ReplicationSlotRelease(void);
+extern void LogReplicationSlotAcquire(bool is_physical, const char *slotname);
+extern void LogReplicationSlotRelease(bool is_physical, const char *slotname);
 extern void ReplicationSlotCleanup(void);
 extern void ReplicationSlotSave(void);
 extern void ReplicationSlotMarkDirty(void);
-- 
2.34.1

From 626dc27e81142cddee656c0140f4570e952e728a Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Fri, 24 Mar 2023 06:11:52 +0000
Subject: [PATCH v10] Add LOG messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 doc/src/sgml/config.sgml            |  7 ++--
 src/backend/replication/slot.c      | 51 +++++++++++++++++++++++++++++
 src/backend/replication/walsender.c | 17 ++++++++++
 src/backend/utils/misc/guc_tables.c |  2 +-
 src/include/replication/slot.h      |  2 ++
 5 files changed, 75 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 481f93cea1..f9b0d3c9a9 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7593,9 +7593,10 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
+        Causes each replication command and related activity to be logged in
+        the server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>.
         Only superusers and users with the appropriate <literal>SET</literal>
         privilege can change this setting.
        </para>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 2293c0c6fc..2caa8a3532 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -180,7 +180,16 @@ ReplicationSlotShmemExit(int code, Datum arg)
 {
 	/* Make sure active replication slots are released */
 	if (MyReplicationSlot != NULL)
+	{
+		bool	is_physical;
+		char	*slotname;
+
+		is_physical = SlotIsPhysical(MyReplicationSlot);
+		slotname = pstrdup(NameStr(MyReplicationSlot->data.name));
 		ReplicationSlotRelease();
+		LogReplicationSlotRelease(is_physical, slotname);
+		pfree(slotname);
+	}
 
 	/* Also cleanup all the temporary slots. */
 	ReplicationSlotCleanup();
@@ -445,6 +454,9 @@ ReplicationSlotName(int index, Name name)
  *
  * An error is raised if nowait is true and the slot is currently in use. If
  * nowait is false, we sleep until the slot is released by the owning process.
+ *
+ * Note: use LogReplicationSlotAcquire() if needed, to log a message after
+ * acquiring the replication slot.
  */
 void
 ReplicationSlotAcquire(const char *name, bool nowait)
@@ -542,6 +554,9 @@ retry:
  *
  * This or another backend can re-acquire the slot later.
  * Resources this slot requires will be preserved.
+ *
+ * Note: use LogReplicationSlotRelease() if needed, to log a message after
+ * releasing the replication slot.
  */
 void
 ReplicationSlotRelease(void)
@@ -596,6 +611,42 @@ ReplicationSlotRelease(void)
 	LWLockRelease(ProcArrayLock);
 }
 
+/*
+ * Helper function to log a message after replication slot acquisition.
+ */
+void
+LogReplicationSlotAcquire(bool is_physical, const char *slotname)
+{
+	Assert(MyReplicationSlot != NULL);
+
+	if (is_physical)
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				errmsg("physical replication slot \"%s\" is acquired",
+					   slotname));
+	else
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				errmsg("logical replication slot \"%s\" is acquired",
+						slotname));
+}
+
+/*
+ * Helper function to log a message after replication slot release.
+ */
+void
+LogReplicationSlotRelease(bool is_physical, const char *slotname)
+{
+	Assert(MyReplicationSlot == NULL);
+
+	if (is_physical)
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				errmsg("physical replication slot \"%s\" is released",
+						slotname));
+	else
+		ereport(log_replication_commands ? LOG : DEBUG3,
+				errmsg("logical replication slot \"%s\" is released",
+						slotname));
+}
+
 /*
  * Cleanup all temporary slots created in current session.
  */
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 75e8363e24..749581b7f1 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -322,7 +322,16 @@ WalSndErrorCleanup(void)
 		wal_segment_close(xlogreader);
 
 	if (MyReplicationSlot != NULL)
+	{
+		bool	is_physical;
+		char	*slotname;
+
+		is_physical = SlotIsPhysical(MyReplicationSlot);
+		slotname = pstrdup(NameStr(MyReplicationSlot->data.name));
 		ReplicationSlotRelease();
+		LogReplicationSlotRelease(is_physical, slotname);
+		pfree(slotname);
+	}
 
 	ReplicationSlotCleanup();
 
@@ -703,6 +712,8 @@ StartReplication(StartReplicationCmd *cmd)
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 					 errmsg("cannot use a logical replication slot for physical replication")));
 
+		LogReplicationSlotAcquire(true, cmd->slotname);
+
 		/*
 		 * We don't need to verify the slot's restart_lsn here; instead we
 		 * rely on the caller requesting the starting point to use.  If the
@@ -843,7 +854,10 @@ StartReplication(StartReplicationCmd *cmd)
 	}
 
 	if (cmd->slotname)
+	{
 		ReplicationSlotRelease();
+		LogReplicationSlotRelease(true, cmd->slotname);
+	}
 
 	/*
 	 * Copy is finished now. Send a single-row result set indicating the next
@@ -1260,6 +1274,8 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 						cmd->slotname),
 				 errdetail("This slot has been invalidated because it exceeded the maximum reserved size.")));
 
+	LogReplicationSlotAcquire(false, cmd->slotname);
+
 	/*
 	 * Force a disconnect, so that the decoding code doesn't need to care
 	 * about an eventual switch from running in recovery, to running in a
@@ -1321,6 +1337,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 
 	FreeDecodingContext(logical_decoding_ctx);
 	ReplicationSlotRelease();
+	LogReplicationSlotRelease(false, cmd->slotname);
 
 	replication_active = false;
 	if (got_STOPPING)
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 1c0583fe26..ea41ccc7e2 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -1203,7 +1203,7 @@ struct config_bool ConfigureNamesBool[] =
 	},
 	{
 		{"log_replication_commands", PGC_SUSET, LOGGING_WHAT,
-			gettext_noop("Logs each replication command."),
+			gettext_noop("Logs each replication command and related activity."),
 			NULL
 		},
 		&log_replication_commands,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 8872c80cdf..d5faf89368 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -202,6 +202,8 @@ extern void ReplicationSlotDrop(const char *name, bool nowait);
 
 extern void ReplicationSlotAcquire(const char *name, bool nowait);
 extern void ReplicationSlotRelease(void);
+extern void LogReplicationSlotAcquire(bool is_physical, const char *slotname);
+extern void LogReplicationSlotRelease(bool is_physical, const char *slotname);
 extern void ReplicationSlotCleanup(void);
 extern void ReplicationSlotSave(void);
 extern void ReplicationSlotMarkDirty(void);
-- 
2.34.1

From eed7c96d9cab98a576728792c2cb111ae61f930f Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Sat, 4 Nov 2023 21:59:27 +0000
Subject: [PATCH v11] Emit messages when replication slots become active and
 inactive

These logs will be extremely useful on production servers to debug
and analyze inactive replication slot issues.
---
 doc/src/sgml/config.sgml            | 10 +++---
 src/backend/replication/slot.c      | 54 ++++++++++++++++++++++++++++-
 src/backend/replication/walsender.c | 10 +++---
 src/include/replication/slot.h      |  2 ++
 4 files changed, 65 insertions(+), 11 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index bd70ff2e4b..6d14a94cf4 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7510,11 +7510,11 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
-        Only superusers and users with the appropriate <literal>SET</literal>
-        privilege can change this setting.
+        Causes each replication command and related activity to be logged in
+        the server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>. Only superusers and users with the appropriate
+        <literal>SET</literal> privilege can change this setting.
        </para>
       </listitem>
      </varlistentry>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 99823df3c7..dfb564b04f 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -181,7 +181,12 @@ ReplicationSlotShmemExit(int code, Datum arg)
 {
 	/* Make sure active replication slots are released */
 	if (MyReplicationSlot != NULL)
-		ReplicationSlotRelease();
+	{
+		if (am_walsender)
+			ReplicationSlotReleaseAndLog();
+		else
+			ReplicationSlotRelease();
+	}
 
 	/* Also cleanup all the temporary slots. */
 	ReplicationSlotCleanup();
@@ -539,6 +544,26 @@ retry:
 		pgstat_acquire_replslot(s);
 }
 
+/*
+ * A wrapper around ReplicationSlotAcquire() but logs a message when
+ * appropriate.
+ *
+ * This function is currently used only in walsender.
+ */
+void
+ReplicationSlotAcquireAndLog(const char *name, bool nowait)
+{
+	Assert(am_walsender);
+
+	ReplicationSlotAcquire(name, nowait);
+
+	ereport(log_replication_commands ? LOG : DEBUG1,
+			(errmsg("walsender process with PID %d acquired %s replication slot \"%s\"",
+					MyProcPid,
+					SlotIsPhysical(MyReplicationSlot) ? "physical" : "logical",
+					NameStr(MyReplicationSlot->data.name))));
+}
+
 /*
  * Release the replication slot that this backend considers to own.
  *
@@ -598,6 +623,33 @@ ReplicationSlotRelease(void)
 	LWLockRelease(ProcArrayLock);
 }
 
+/*
+ * A wrapper around ReplicationSlotAcquire() but logs a message when
+ * appropriate.
+ *
+ * This function is currently used only in walsender.
+ */
+void
+ReplicationSlotReleaseAndLog(void)
+{
+	char	   *slotname;
+	bool		is_physical;
+
+	Assert(am_walsender);
+
+	slotname = pstrdup(NameStr(MyReplicationSlot->data.name));
+	is_physical = SlotIsPhysical(MyReplicationSlot);
+
+	ReplicationSlotRelease();
+
+	ereport(log_replication_commands ? LOG : DEBUG1,
+			(errmsg("walsender process with PID %d released %s replication slot \"%s\"",
+					MyProcPid,
+					is_physical ? "physical" : "logical", slotname)));
+
+	pfree(slotname);
+}
+
 /*
  * Cleanup all temporary slots created in current session.
  */
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index e250b0567e..2a1c5056c0 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -322,7 +322,7 @@ WalSndErrorCleanup(void)
 		wal_segment_close(xlogreader);
 
 	if (MyReplicationSlot != NULL)
-		ReplicationSlotRelease();
+		ReplicationSlotReleaseAndLog();
 
 	ReplicationSlotCleanup();
 
@@ -697,7 +697,7 @@ StartReplication(StartReplicationCmd *cmd)
 
 	if (cmd->slotname)
 	{
-		ReplicationSlotAcquire(cmd->slotname, true);
+		ReplicationSlotAcquireAndLog(cmd->slotname, true);
 		if (SlotIsLogical(MyReplicationSlot))
 			ereport(ERROR,
 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
@@ -843,7 +843,7 @@ StartReplication(StartReplicationCmd *cmd)
 	}
 
 	if (cmd->slotname)
-		ReplicationSlotRelease();
+		ReplicationSlotReleaseAndLog();
 
 	/*
 	 * Copy is finished now. Send a single-row result set indicating the next
@@ -1261,7 +1261,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 
 	Assert(!MyReplicationSlot);
 
-	ReplicationSlotAcquire(cmd->slotname, true);
+	ReplicationSlotAcquireAndLog(cmd->slotname, true);
 
 	/*
 	 * Force a disconnect, so that the decoding code doesn't need to care
@@ -1323,7 +1323,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
 	WalSndLoop(XLogSendLogical);
 
 	FreeDecodingContext(logical_decoding_ctx);
-	ReplicationSlotRelease();
+	ReplicationSlotReleaseAndLog();
 
 	replication_active = false;
 	if (got_STOPPING)
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index d3535eed58..3dc8699106 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -223,7 +223,9 @@ extern void ReplicationSlotPersist(void);
 extern void ReplicationSlotDrop(const char *name, bool nowait);
 
 extern void ReplicationSlotAcquire(const char *name, bool nowait);
+extern void ReplicationSlotAcquireAndLog(const char *name, bool nowait);
 extern void ReplicationSlotRelease(void);
+extern void ReplicationSlotReleaseAndLog(void);
 extern void ReplicationSlotCleanup(void);
 extern void ReplicationSlotSave(void);
 extern void ReplicationSlotMarkDirty(void);
-- 
2.34.1

From cd784c50ed0fc928241f109e19f0f5c9afaa01ef Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Mon, 13 Nov 2023 12:04:11 +0000
Subject: [PATCH v12] Emit messages when replication slots become active and
 inactive

This commit adds log messages (at LOG level when
log_replication_commands is set, otherwise at DEBUG1 level) when
walsenders acquire and release replication slots. These messages
help to know the lifetime of a replication slot - one can know how
long a streaming standby or logical subscriber or replication slot
consumer is down. In other words, one can know how long a
replication slot is inactive - the time between released and
acquired slot messages is the inactive replication slot duration.
These messages will be extremely useful on production servers to
debug and analyze inactive replication slot issues.

Note that these messages are emitted only for walsenders when
replication slot is acquired and released, but not for backends.
This is because walsenders are the ones that typically hold
replication slots for longer durations unlike backends which hold
replication slots for executing some replication related
functions.
---
 doc/src/sgml/config.sgml       | 10 +++++-----
 src/backend/replication/slot.c | 23 +++++++++++++++++++++++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fc35a46e5e..1dc014ce84 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7510,11 +7510,11 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
-        Only superusers and users with the appropriate <literal>SET</literal>
-        privilege can change this setting.
+        Causes each replication command and slot acquisition/release to be
+        logged in the server log. See <xref linkend="protocol-replication"/>
+        for more information about replication command. The default value is
+        <literal>off</literal>. Only superusers and users with the appropriate
+        <literal>SET</literal> privilege can change this setting.
        </para>
       </listitem>
      </varlistentry>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 781aa43cc4..fd8b8151b6 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -537,6 +537,12 @@ retry:
 	 */
 	if (SlotIsLogical(s))
 		pgstat_acquire_replslot(s);
+
+	if (am_walsender)
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				errmsg_internal("acquired %s replication slot \"%s\"",
+								SlotIsPhysical(MyReplicationSlot) ? "physical" : "logical",
+								NameStr(MyReplicationSlot->data.name)));
 }
 
 /*
@@ -549,9 +555,17 @@ void
 ReplicationSlotRelease(void)
 {
 	ReplicationSlot *slot = MyReplicationSlot;
+	char	   *slotname;
+	bool		is_physical;
 
 	Assert(slot != NULL && slot->active_pid != 0);
 
+	if (am_walsender)
+	{
+		slotname = pstrdup(NameStr(MyReplicationSlot->data.name));
+		is_physical = SlotIsPhysical(MyReplicationSlot);
+	}
+
 	if (slot->data.persistency == RS_EPHEMERAL)
 	{
 		/*
@@ -596,6 +610,15 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				errmsg_internal("released %s replication slot \"%s\"",
+								is_physical ? "physical" : "logical", slotname));
+
+		pfree(slotname);
+	}
 }
 
 /*
-- 
2.34.1

From 390cd5c81518f209e30e7dde3220185ae006b04d Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Mon, 13 Nov 2023 14:08:23 +0000
Subject: [PATCH v13] Log messages for replication slot acquisition and release

This commit adds log messages (at LOG level when
log_replication_commands is set, otherwise at DEBUG1 level) when
walsenders acquire and release replication slots. These messages
help to know the lifetime of a replication slot - one can know how
long a streaming standby or logical subscriber or replication slot
consumer is down. In other words, one can know how long a
replication slot is inactive - the time between released and
acquired slot messages is the inactive replication slot duration.
These messages will be extremely useful on production servers to
debug and analyze inactive replication slot issues.

Note that these messages are emitted only for walsenders when
replication slot is acquired and released, but not for backends.
This is because walsenders are the ones that typically hold
replication slots for longer durations unlike backends which hold
replication slots for executing some replication related
functions.
---
 doc/src/sgml/config.sgml       | 10 +++++-----
 src/backend/replication/slot.c | 24 ++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fc35a46e5e..1dc014ce84 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7510,11 +7510,11 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
-        Only superusers and users with the appropriate <literal>SET</literal>
-        privilege can change this setting.
+        Causes each replication command and slot acquisition/release to be
+        logged in the server log. See <xref linkend="protocol-replication"/>
+        for more information about replication command. The default value is
+        <literal>off</literal>. Only superusers and users with the appropriate
+        <literal>SET</literal> privilege can change this setting.
        </para>
       </listitem>
      </varlistentry>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 781aa43cc4..379aece031 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -537,6 +537,12 @@ retry:
 	 */
 	if (SlotIsLogical(s))
 		pgstat_acquire_replslot(s);
+
+	if (am_walsender)
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				errmsg_internal("acquired %s replication slot \"%s\"",
+								SlotIsPhysical(MyReplicationSlot) ? "physical" : "logical",
+								NameStr(MyReplicationSlot->data.name)));
 }
 
 /*
@@ -549,9 +555,17 @@ void
 ReplicationSlotRelease(void)
 {
 	ReplicationSlot *slot = MyReplicationSlot;
+	char	   *slotname = NULL;	/* keep compiler quiet */
+	bool		is_physical = false;	/* keep compiler quiet */
 
 	Assert(slot != NULL && slot->active_pid != 0);
 
+	if (am_walsender)
+	{
+		slotname = pstrdup(NameStr(MyReplicationSlot->data.name));
+		is_physical = SlotIsPhysical(MyReplicationSlot);
+	}
+
 	if (slot->data.persistency == RS_EPHEMERAL)
 	{
 		/*
@@ -596,6 +610,16 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				errmsg_internal("released %s replication slot \"%s\"",
+								is_physical ? "physical" : "logical",
+								slotname));
+
+		pfree(slotname);
+	}
 }
 
 /*
-- 
2.34.1

From 87d04d040fc048af2065f34c6c5887c84d4e15da Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Tue, 14 Nov 2023 06:53:02 +0000
Subject: [PATCH v14] Log messages for replication slot acquisition and release

This commit adds log messages (at LOG level when
log_replication_commands is set, otherwise at DEBUG1 level) when
walsenders acquire and release replication slots. These messages
help to know the lifetime of a replication slot - one can know how
long a streaming standby or logical subscriber or replication slot
consumer is down. In other words, one can know how long a
replication slot is inactive - the time between released and
acquired slot messages is the inactive replication slot duration.
These messages will be extremely useful on production servers to
debug and analyze inactive replication slot issues.

Note that these messages are emitted only for walsenders when
replication slot is acquired and released, but not for backends.
This is because walsenders are the ones that typically hold
replication slots for longer durations unlike backends which hold
replication slots for executing some replication related
functions.
---
 doc/src/sgml/config.sgml       |  7 ++++---
 src/backend/replication/slot.c | 24 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fc35a46e5e..d87320141a 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7510,9 +7510,10 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
+        Causes each replication command and <literal>walsender</literal>
+        process replication slot acquisition/release to be logged in the server
+        log. See <xref linkend="protocol-replication"/> for more information
+        about replication command. The default value is <literal>off</literal>.
         Only superusers and users with the appropriate <literal>SET</literal>
         privilege can change this setting.
        </para>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 781aa43cc4..5d6ba0aef1 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -537,6 +537,12 @@ retry:
 	 */
 	if (SlotIsLogical(s))
 		pgstat_acquire_replslot(s);
+
+	if (am_walsender)
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				errmsg_internal("acquired %s replication slot \"%s\"",
+								SlotIsLogical(s) ? "logical" : "physical",
+								NameStr(s->data.name)));
 }
 
 /*
@@ -549,9 +555,17 @@ void
 ReplicationSlotRelease(void)
 {
 	ReplicationSlot *slot = MyReplicationSlot;
+	char	   *slotname = NULL;	/* keep compiler quiet */
+	bool		is_logical = false; /* keep compiler quiet */
 
 	Assert(slot != NULL && slot->active_pid != 0);
 
+	if (am_walsender)
+	{
+		slotname = pstrdup(NameStr(slot->data.name));
+		is_logical = SlotIsLogical(slot);
+	}
+
 	if (slot->data.persistency == RS_EPHEMERAL)
 	{
 		/*
@@ -596,6 +610,16 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				errmsg_internal("released %s replication slot \"%s\"",
+								is_logical ? "logical" : "physical",
+								slotname));
+
+		pfree(slotname);
+	}
 }
 
 /*
-- 
2.34.1

From 3cf4416fc01cd27bf90059e136dc008b8b5b726f Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Wed, 15 Nov 2023 05:21:45 +0000
Subject: [PATCH v15] Log messages for replication slot acquisition and release

This commit adds log messages (at LOG level when
log_replication_commands is set, otherwise at DEBUG1 level) when
walsenders acquire and release replication slots. These messages
help to know the lifetime of a replication slot - one can know how
long a streaming standby or logical subscriber or replication slot
consumer is down. In other words, one can know how long a
replication slot is inactive - the time between released and
acquired slot messages is the inactive replication slot duration.
These messages will be extremely useful on production servers to
debug and analyze inactive replication slot issues.

Note that these messages are emitted only for walsenders when
replication slot is acquired and released, but not for backends.
This is because walsenders are the ones that typically hold
replication slots for longer durations unlike backends which hold
replication slots for executing some replication related
functions.
---
 doc/src/sgml/config.sgml       | 11 ++++++-----
 src/backend/replication/slot.c | 36 ++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fc35a46e5e..9398afbcbd 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7510,11 +7510,12 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
-        Only superusers and users with the appropriate <literal>SET</literal>
-        privilege can change this setting.
+        Causes each replication command and <literal>walsender</literal>
+        process's replication slot acquisition/release to be logged in the
+        server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>. Only superusers and users with the appropriate
+        <literal>SET</literal> privilege can change this setting.
        </para>
       </listitem>
      </varlistentry>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 781aa43cc4..bac21244bd 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -537,6 +537,19 @@ retry:
 	 */
 	if (SlotIsLogical(s))
 		pgstat_acquire_replslot(s);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+
+		/*
+		 * translator: first %s is replication slot type, eg logical or
+		 * physical
+		 */
+				errmsg("acquired %s replication slot \"%s\"",
+					   SlotIsLogical(s) ? "logical" : "physical",
+					   NameStr(s->data.name)));
+	}
 }
 
 /*
@@ -549,9 +562,17 @@ void
 ReplicationSlotRelease(void)
 {
 	ReplicationSlot *slot = MyReplicationSlot;
+	char	   *slotname = NULL;	/* keep compiler quiet */
+	bool		is_logical = false; /* keep compiler quiet */
 
 	Assert(slot != NULL && slot->active_pid != 0);
 
+	if (am_walsender)
+	{
+		slotname = pstrdup(NameStr(slot->data.name));
+		is_logical = SlotIsLogical(slot);
+	}
+
 	if (slot->data.persistency == RS_EPHEMERAL)
 	{
 		/*
@@ -596,6 +617,21 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+
+		/*
+		 * translator: first %s is replication slot type, eg logical or
+		 * physical
+		 */
+				errmsg("released %s replication slot \"%s\"",
+					   is_logical ? "logical" : "physical",
+					   slotname));
+
+		pfree(slotname);
+	}
 }
 
 /*
-- 
2.34.1

From 9e76c6bef0350718d36a6db5993baa4cdeacc5e3 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Wed, 15 Nov 2023 05:21:45 +0000
Subject: [PATCH v16] Log messages for replication slot acquisition and
 release.

This commit log messages (at LOG level when log_replication_commands is
set, otherwise at DEBUG1 level) when walsenders acquire and release
replication slots. These messages help to know the lifetime of a
replication slot - one can know how long a streaming standby, logical
subscriber, or replication slot consumer is down. These messages will be
useful on production servers to debug and analyze inactive replication
slots.

Note that these messages are emitted only for walsenders but not for
backends. This is because walsenders are the ones that typically hold
replication slots for longer durations, unlike backends which hold them
for executing replication related functions.

Author: Bharath Rupireddy
Reviewed-by: Peter Smith, Amit Kapila
Discussion: http://postgr.es/m/CALj2ACX17G7F-jeLt+7KhJ6YxVeRwR8Zk0rDh4VnT546o0UpTQ@mail.gmail.com
---
 doc/src/sgml/config.sgml       | 11 ++++++-----
 src/backend/replication/slot.c | 28 ++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fc35a46e5e..9398afbcbd 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7510,11 +7510,12 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
-        Only superusers and users with the appropriate <literal>SET</literal>
-        privilege can change this setting.
+        Causes each replication command and <literal>walsender</literal>
+        process's replication slot acquisition/release to be logged in the
+        server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>. Only superusers and users with the appropriate
+        <literal>SET</literal> privilege can change this setting.
        </para>
       </listitem>
      </varlistentry>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 781aa43cc4..6f014d0df5 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -537,6 +537,15 @@ retry:
 	 */
 	if (SlotIsLogical(s))
 		pgstat_acquire_replslot(s);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+		/* translator: first %s is logical or physical slot */
+				errmsg("acquired %s replication slot \"%s\"",
+					   SlotIsLogical(s) ? "logical" : "physical",
+					   NameStr(s->data.name)));
+	}
 }
 
 /*
@@ -549,9 +558,17 @@ void
 ReplicationSlotRelease(void)
 {
 	ReplicationSlot *slot = MyReplicationSlot;
+	char	   *slotname = NULL;	/* keep compiler quiet */
+	bool		is_logical = false; /* keep compiler quiet */
 
 	Assert(slot != NULL && slot->active_pid != 0);
 
+	if (am_walsender)
+	{
+		slotname = pstrdup(NameStr(slot->data.name));
+		is_logical = SlotIsLogical(slot);
+	}
+
 	if (slot->data.persistency == RS_EPHEMERAL)
 	{
 		/*
@@ -596,6 +613,17 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+		/* translator: first %s is logical or physical slot */
+				errmsg("released %s replication slot \"%s\"",
+					   is_logical ? "logical" : "physical",
+					   slotname));
+
+		pfree(slotname);
+	}
 }
 
 /*
-- 
2.28.0.windows.1

From eb5b165fb09652baf226292362a0df4fcff5714c Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Wed, 15 Nov 2023 18:27:30 +0000
Subject: [PATCH v17] Log messages for replication slot acquisition and
 release.

This commit log messages (at LOG level when log_replication_commands is
set, otherwise at DEBUG1 level) when walsenders acquire and release
replication slots. These messages help to know the lifetime of a
replication slot - one can know how long a streaming standby, logical
subscriber, or replication slot consumer is down. These messages will be
useful on production servers to debug and analyze inactive replication
slots.

Note that these messages are emitted only for walsenders but not for
backends. This is because walsenders are the ones that typically hold
replication slots for longer durations, unlike backends which hold them
for executing replication related functions.

Author: Bharath Rupireddy
Reviewed-by: Peter Smith, Amit Kapila
Discussion: http://postgr.es/m/CALj2ACX17G7F-jeLt+7KhJ6YxVeRwR8Zk0rDh4VnT546o0UpTQ@mail.gmail.com
---
 doc/src/sgml/config.sgml       | 11 ++++++-----
 src/backend/replication/slot.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fc35a46e5e..9398afbcbd 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7510,11 +7510,12 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
-        Only superusers and users with the appropriate <literal>SET</literal>
-        privilege can change this setting.
+        Causes each replication command and <literal>walsender</literal>
+        process's replication slot acquisition/release to be logged in the
+        server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>. Only superusers and users with the appropriate
+        <literal>SET</literal> privilege can change this setting.
        </para>
       </listitem>
      </varlistentry>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 781aa43cc4..2bfdbd5e80 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -537,6 +537,17 @@ retry:
 	 */
 	if (SlotIsLogical(s))
 		pgstat_acquire_replslot(s);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				SlotIsLogical(s)
+		/* translator: %s is name of the replication slot */
+				? errmsg("acquired logical replication slot \"%s\"",
+						 NameStr(s->data.name))
+				: errmsg("acquired physical replication slot \"%s\"",
+						 NameStr(s->data.name)));
+	}
 }
 
 /*
@@ -549,9 +560,17 @@ void
 ReplicationSlotRelease(void)
 {
 	ReplicationSlot *slot = MyReplicationSlot;
+	char	   *slotname = NULL;	/* keep compiler quiet */
+	bool		is_logical = false; /* keep compiler quiet */
 
 	Assert(slot != NULL && slot->active_pid != 0);
 
+	if (am_walsender)
+	{
+		slotname = pstrdup(NameStr(slot->data.name));
+		is_logical = SlotIsLogical(slot);
+	}
+
 	if (slot->data.persistency == RS_EPHEMERAL)
 	{
 		/*
@@ -596,6 +615,19 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				is_logical
+		/* translator: %s is name of the replication slot */
+				? errmsg("released logical replication slot \"%s\"",
+						 slotname)
+				: errmsg("released physical replication slot \"%s\"",
+						 slotname));
+
+		pfree(slotname);
+	}
 }
 
 /*
-- 
2.34.1

From 8e0fe98061ad5c49f42f8595f157d312daad7c04 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Thu, 16 Nov 2023 12:26:10 +0000
Subject: [PATCH v18] Log messages for replication slot acquisition and
 release.

This commit log messages (at LOG level when log_replication_commands is
set, otherwise at DEBUG1 level) when walsenders acquire and release
replication slots. These messages help to know the lifetime of a
replication slot - one can know how long a streaming standby, logical
subscriber, or replication slot consumer is down. These messages will be
useful on production servers to debug and analyze inactive replication
slots.

Note that these messages are emitted only for walsenders but not for
backends. This is because walsenders are the ones that typically hold
replication slots for longer durations, unlike backends which hold them
for executing replication related functions.

Author: Bharath Rupireddy
Reviewed-by: Peter Smith, Amit Kapila, Alvaro Herrera
Discussion: http://postgr.es/m/CALj2ACX17G7F-jeLt+7KhJ6YxVeRwR8Zk0rDh4VnT546o0UpTQ@mail.gmail.com
---
 doc/src/sgml/config.sgml       | 11 ++++++-----
 src/backend/replication/slot.c | 30 ++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fc35a46e5e..9398afbcbd 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7510,11 +7510,12 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
       </term>
       <listitem>
        <para>
-        Causes each replication command to be logged in the server log.
-        See <xref linkend="protocol-replication"/> for more information about
-        replication command. The default value is <literal>off</literal>.
-        Only superusers and users with the appropriate <literal>SET</literal>
-        privilege can change this setting.
+        Causes each replication command and <literal>walsender</literal>
+        process's replication slot acquisition/release to be logged in the
+        server log. See <xref linkend="protocol-replication"/> for more
+        information about replication command. The default value is
+        <literal>off</literal>. Only superusers and users with the appropriate
+        <literal>SET</literal> privilege can change this setting.
        </para>
       </listitem>
      </varlistentry>
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 781aa43cc4..18bc28195b 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -537,6 +537,16 @@ retry:
 	 */
 	if (SlotIsLogical(s))
 		pgstat_acquire_replslot(s);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				SlotIsLogical(s)
+				? errmsg("acquired logical replication slot \"%s\"",
+						 NameStr(s->data.name))
+				: errmsg("acquired physical replication slot \"%s\"",
+						 NameStr(s->data.name)));
+	}
 }
 
 /*
@@ -549,9 +559,17 @@ void
 ReplicationSlotRelease(void)
 {
 	ReplicationSlot *slot = MyReplicationSlot;
+	char	   *slotname = NULL;	/* keep compiler quiet */
+	bool		is_logical = false; /* keep compiler quiet */
 
 	Assert(slot != NULL && slot->active_pid != 0);
 
+	if (am_walsender)
+	{
+		slotname = pstrdup(NameStr(slot->data.name));
+		is_logical = SlotIsLogical(slot);
+	}
+
 	if (slot->data.persistency == RS_EPHEMERAL)
 	{
 		/*
@@ -596,6 +614,18 @@ ReplicationSlotRelease(void)
 	MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
 	ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
 	LWLockRelease(ProcArrayLock);
+
+	if (am_walsender)
+	{
+		ereport(log_replication_commands ? LOG : DEBUG1,
+				is_logical
+				? errmsg("released logical replication slot \"%s\"",
+						 slotname)
+				: errmsg("released physical replication slot \"%s\"",
+						 slotname));
+
+		pfree(slotname);
+	}
 }
 
 /*
-- 
2.34.1