START_REPLICATION SLOT causing a crash in an assert build

diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index b77c05ab5f..db44d51b4c 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -65,6 +65,7 @@ pgstat_reset_replslot(const char *name)
        /* reset this one entry */
        pgstat_reset(PGSTAT_KIND_REPLSLOT, InvalidOid,
                                 ReplicationSlotIndex(slot));
+       namestrcpy(&slot->data.name, name);
 }
 
 /*

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index 6224c498c2..ab88ebbc64 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -263,6 +263,8 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 		.shared_size = sizeof(PgStatShared_Database),
 		.shared_data_off = offsetof(PgStatShared_Database, stats),
 		.shared_data_len = sizeof(((PgStatShared_Database *) 0)->stats),
+		.reset_off = offsetof(PgStatShared_Database, stats),
+		.reset_len = sizeof(((PgStatShared_Database *) 0)->stats),
 		.pending_size = sizeof(PgStat_StatDBEntry),
 
 		.flush_pending_cb = pgstat_database_flush_cb,
@@ -277,6 +279,8 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 		.shared_size = sizeof(PgStatShared_Relation),
 		.shared_data_off = offsetof(PgStatShared_Relation, stats),
 		.shared_data_len = sizeof(((PgStatShared_Relation *) 0)->stats),
+		.reset_off = offsetof(PgStatShared_Relation, stats),
+		.reset_len = sizeof(((PgStatShared_Relation *) 0)->stats),
 		.pending_size = sizeof(PgStat_TableStatus),
 
 		.flush_pending_cb = pgstat_relation_flush_cb,
@@ -291,6 +295,8 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 		.shared_size = sizeof(PgStatShared_Function),
 		.shared_data_off = offsetof(PgStatShared_Function, stats),
 		.shared_data_len = sizeof(((PgStatShared_Function *) 0)->stats),
+		.reset_off = offsetof(PgStatShared_Function, stats),
+		.reset_len = sizeof(((PgStatShared_Function *) 0)->stats),
 		.pending_size = sizeof(PgStat_BackendFunctionEntry),
 
 		.flush_pending_cb = pgstat_function_flush_cb,
@@ -307,6 +313,9 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 		.shared_size = sizeof(PgStatShared_ReplSlot),
 		.shared_data_off = offsetof(PgStatShared_ReplSlot, stats),
 		.shared_data_len = sizeof(((PgStatShared_ReplSlot *) 0)->stats),
+		.reset_off = offsetof(PgStatShared_ReplSlot, stats.spill_txns),
+		.reset_len = sizeof(PgStatShared_ReplSlot) -
+		offsetof(PgStatShared_ReplSlot, stats.spill_txns),
 
 		.reset_timestamp_cb = pgstat_replslot_reset_timestamp_cb,
 		.to_serialized_name = pgstat_replslot_to_serialized_name_cb,
@@ -323,6 +332,8 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 		.shared_size = sizeof(PgStatShared_Subscription),
 		.shared_data_off = offsetof(PgStatShared_Subscription, stats),
 		.shared_data_len = sizeof(((PgStatShared_Subscription *) 0)->stats),
+		.reset_off = offsetof(PgStatShared_Subscription, stats),
+		.reset_len = sizeof(((PgStatShared_Subscription *) 0)->stats),
 		.pending_size = sizeof(PgStat_BackendSubEntry),
 
 		.flush_pending_cb = pgstat_subscription_flush_cb,
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index ac98918688..09a8c3873c 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -915,8 +915,9 @@ shared_stat_reset_contents(PgStat_Kind kind, PgStatShared_Common *header,
 {
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
-	memset(pgstat_get_entry_data(kind, header), 0,
-		   pgstat_get_entry_len(kind));
+	memset((char *)pgstat_get_entry_data(kind, header) +
+		   kind_info->reset_off, 0,
+		   kind_info->reset_len);
 
 	if (kind_info->reset_timestamp_cb)
 		kind_info->reset_timestamp_cb(header, ts);
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 901d2041d6..3715a48776 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -215,6 +215,12 @@ typedef struct PgStat_KindInfo
 	uint32		shared_data_off;
 	uint32		shared_data_len;
 
+	/*
+	 * The offset/size of the region to wipe out when the entry is reset.
+	 */
+	uint32		reset_off;
+	uint32		reset_len;
+
 	/*
 	 * The size of the pending data for this kind. E.g. how large
 	 * PgStat_EntryRef->pending is. Used for allocations.

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index 6224c498c2..ed3f3af4d9 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -263,6 +263,8 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 		.shared_size = sizeof(PgStatShared_Database),
 		.shared_data_off = offsetof(PgStatShared_Database, stats),
 		.shared_data_len = sizeof(((PgStatShared_Database *) 0)->stats),
+		.reset_off = 0,
+		.reset_len = sizeof(((PgStatShared_Database *) 0)->stats),
 		.pending_size = sizeof(PgStat_StatDBEntry),
 
 		.flush_pending_cb = pgstat_database_flush_cb,
@@ -277,6 +279,8 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 		.shared_size = sizeof(PgStatShared_Relation),
 		.shared_data_off = offsetof(PgStatShared_Relation, stats),
 		.shared_data_len = sizeof(((PgStatShared_Relation *) 0)->stats),
+		.reset_off = 0,
+		.reset_len = sizeof(((PgStatShared_Relation *) 0)->stats),
 		.pending_size = sizeof(PgStat_TableStatus),
 
 		.flush_pending_cb = pgstat_relation_flush_cb,
@@ -291,6 +295,8 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 		.shared_size = sizeof(PgStatShared_Function),
 		.shared_data_off = offsetof(PgStatShared_Function, stats),
 		.shared_data_len = sizeof(((PgStatShared_Function *) 0)->stats),
+		.reset_off = 0,
+		.reset_len = sizeof(((PgStatShared_Function *) 0)->stats),
 		.pending_size = sizeof(PgStat_BackendFunctionEntry),
 
 		.flush_pending_cb = pgstat_function_flush_cb,
@@ -307,6 +313,10 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 		.shared_size = sizeof(PgStatShared_ReplSlot),
 		.shared_data_off = offsetof(PgStatShared_ReplSlot, stats),
 		.shared_data_len = sizeof(((PgStatShared_ReplSlot *) 0)->stats),
+		/* reset doesn't wipe off slot name */
+		.reset_off = offsetof(PgStat_StatReplSlotEntry, spill_txns),
+		.reset_len = sizeof(((PgStatShared_ReplSlot *) 0)->stats),
+		offsetof(PgStat_StatReplSlotEntry, spill_txns),
 
 		.reset_timestamp_cb = pgstat_replslot_reset_timestamp_cb,
 		.to_serialized_name = pgstat_replslot_to_serialized_name_cb,
@@ -323,6 +333,8 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 		.shared_size = sizeof(PgStatShared_Subscription),
 		.shared_data_off = offsetof(PgStatShared_Subscription, stats),
 		.shared_data_len = sizeof(((PgStatShared_Subscription *) 0)->stats),
+		.reset_off = 0,
+		.reset_len = sizeof(((PgStatShared_Subscription *) 0)->stats),
 		.pending_size = sizeof(PgStat_BackendSubEntry),
 
 		.flush_pending_cb = pgstat_subscription_flush_cb,
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index ac98918688..09a8c3873c 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -915,8 +915,9 @@ shared_stat_reset_contents(PgStat_Kind kind, PgStatShared_Common *header,
 {
 	const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
 
-	memset(pgstat_get_entry_data(kind, header), 0,
-		   pgstat_get_entry_len(kind));
+	memset((char *)pgstat_get_entry_data(kind, header) +
+		   kind_info->reset_off, 0,
+		   kind_info->reset_len);
 
 	if (kind_info->reset_timestamp_cb)
 		kind_info->reset_timestamp_cb(header, ts);
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 901d2041d6..144fe5814c 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -215,6 +215,13 @@ typedef struct PgStat_KindInfo
 	uint32		shared_data_off;
 	uint32		shared_data_len;
 
+	/*
+	 * The offset/size of the region to wipe out when the entry is reset.
+	 * reset_off is relative to shared_data_off.
+	 */
+	uint32		reset_off;
+	uint32		reset_len;
+
 	/*
 	 * The size of the pending data for this kind. E.g. how large
 	 * PgStat_EntryRef->pending is. Used for allocations.

From 5789b35c1eca77ad63066e6671921e1e8a656372 Mon Sep 17 00:00:00 2001
From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Date: Tue, 27 Sep 2022 14:28:56 +0900
Subject: [PATCH v1] Do not reset slot name of replication slot stats

pg_stat_reset_replication_slot() clears counters involving slot name,
which is not intended and causes crash.  Move slot name out of
PgStat_StatReplSlotEntry to PgStatShared_Database so that the name
won't be wiped out by a counter reset.
---
 src/backend/utils/activity/pgstat_replslot.c | 12 ++++++------
 src/include/pgstat.h                         |  1 -
 src/include/utils/pgstat_internal.h          |  1 +
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index 2039ac3147..0a383f9f32 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -86,7 +86,7 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	 * Any mismatch should have been fixed in pgstat_create_replslot() or
 	 * pgstat_acquire_replslot().
 	 */
-	Assert(namestrcmp(&statent->slotname, NameStr(slot->data.name)) == 0);
+	Assert(namestrcmp(&shstatent->slotname, NameStr(slot->data.name)) == 0);
 
 	/* Update the replication slot statistics */
 #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
@@ -124,7 +124,7 @@ pgstat_create_replslot(ReplicationSlot *slot)
 	 * if we previously crashed after dropping a slot.
 	 */
 	memset(&shstatent->stats, 0, sizeof(shstatent->stats));
-	namestrcpy(&shstatent->stats.slotname, NameStr(slot->data.name));
+	namestrcpy(&shstatent->slotname, NameStr(slot->data.name));
 
 	pgstat_unlock_entry(entry_ref);
 }
@@ -148,11 +148,11 @@ pgstat_acquire_replslot(ReplicationSlot *slot)
 	 * NB: need to accept that there might be stats from an older slot, e.g.
 	 * if we previously crashed after dropping a slot.
 	 */
-	if (NameStr(statent->slotname)[0] == 0 ||
-		namestrcmp(&statent->slotname, NameStr(slot->data.name)) != 0)
+	if (NameStr(shstatent->slotname)[0] == 0 ||
+		namestrcmp(&shstatent->slotname, NameStr(slot->data.name)) != 0)
 	{
 		memset(statent, 0, sizeof(*statent));
-		namestrcpy(&statent->slotname, NameStr(slot->data.name));
+		namestrcpy(&shstatent->slotname, NameStr(slot->data.name));
 	}
 
 	pgstat_unlock_entry(entry_ref);
@@ -187,7 +187,7 @@ pgstat_fetch_replslot(NameData slotname)
 void
 pgstat_replslot_to_serialized_name_cb(const PgStatShared_Common *header, NameData *name)
 {
-	namestrcpy(name, NameStr(((PgStatShared_ReplSlot *) header)->stats.slotname));
+	namestrcpy(name, NameStr(((PgStatShared_ReplSlot *) header)->slotname));
 }
 
 bool
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index ad7334a0d2..530d49e5c3 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -321,7 +321,6 @@ typedef struct PgStat_StatFuncEntry
 
 typedef struct PgStat_StatReplSlotEntry
 {
-	NameData	slotname;
 	PgStat_Counter spill_txns;
 	PgStat_Counter spill_count;
 	PgStat_Counter spill_bytes;
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 40a3602855..9bdcc08ed3 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -380,6 +380,7 @@ typedef struct PgStatShared_Subscription
 typedef struct PgStatShared_ReplSlot
 {
 	PgStatShared_Common header;
+	NameData	slotname;
 	PgStat_StatReplSlotEntry stats;
 } PgStatShared_ReplSlot;
 
-- 
2.31.1

From 4effe9279d6535191d7f5478bb76490dc8762d33 Mon Sep 17 00:00:00 2001
From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Date: Thu, 6 Oct 2022 14:06:04 +0900
Subject: [PATCH v2] If we avoid file format

---
 src/backend/utils/activity/pgstat.c          |  9 +++++++--
 src/backend/utils/activity/pgstat_replslot.c | 18 ++++++++++++------
 src/include/pgstat.h                         |  1 -
 src/include/utils/pgstat_internal.h          |  3 +++
 4 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index 609f0b1ad8..a03184c9ef 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -310,6 +310,7 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
 
 		.reset_timestamp_cb = pgstat_replslot_reset_timestamp_cb,
 		.to_serialized_name = pgstat_replslot_to_serialized_name_cb,
+		.set_name = pgstat_replslot_set_name_cb,
 		.from_serialized_name = pgstat_replslot_from_serialized_name_cb,
 	},
 
@@ -1523,6 +1524,8 @@ pgstat_read_statsfile(void)
 					PgStat_HashKey key;
 					PgStatShared_HashEntry *p;
 					PgStatShared_Common *header;
+					const PgStat_KindInfo *kind_info = NULL;
+					NameData	name = {0};
 
 					CHECK_FOR_INTERRUPTS();
 
@@ -1538,9 +1541,7 @@ pgstat_read_statsfile(void)
 					else
 					{
 						/* stats entry identified by name on disk (e.g. slots) */
-						const PgStat_KindInfo *kind_info = NULL;
 						PgStat_Kind kind;
-						NameData	name;
 
 						if (!read_chunk_s(fpin, &kind))
 							goto error;
@@ -1590,6 +1591,10 @@ pgstat_read_statsfile(void)
 									pgstat_get_entry_len(key.kind)))
 						goto error;
 
+					/* set name if it requires to do that separately */
+					if (kind_info && kind_info->set_name && NameStr(name)[0])
+						kind_info->set_name(header, &name);
+						
 					break;
 				}
 			case 'E':
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index 2039ac3147..9fa4df610d 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -86,7 +86,7 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	 * Any mismatch should have been fixed in pgstat_create_replslot() or
 	 * pgstat_acquire_replslot().
 	 */
-	Assert(namestrcmp(&statent->slotname, NameStr(slot->data.name)) == 0);
+	Assert(namestrcmp(&shstatent->slotname, NameStr(slot->data.name)) == 0);
 
 	/* Update the replication slot statistics */
 #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
@@ -124,7 +124,7 @@ pgstat_create_replslot(ReplicationSlot *slot)
 	 * if we previously crashed after dropping a slot.
 	 */
 	memset(&shstatent->stats, 0, sizeof(shstatent->stats));
-	namestrcpy(&shstatent->stats.slotname, NameStr(slot->data.name));
+	namestrcpy(&shstatent->slotname, NameStr(slot->data.name));
 
 	pgstat_unlock_entry(entry_ref);
 }
@@ -148,11 +148,11 @@ pgstat_acquire_replslot(ReplicationSlot *slot)
 	 * NB: need to accept that there might be stats from an older slot, e.g.
 	 * if we previously crashed after dropping a slot.
 	 */
-	if (NameStr(statent->slotname)[0] == 0 ||
-		namestrcmp(&statent->slotname, NameStr(slot->data.name)) != 0)
+	if (NameStr(shstatent->slotname)[0] == 0 ||
+		namestrcmp(&shstatent->slotname, NameStr(slot->data.name)) != 0)
 	{
 		memset(statent, 0, sizeof(*statent));
-		namestrcpy(&statent->slotname, NameStr(slot->data.name));
+		namestrcpy(&shstatent->slotname, NameStr(slot->data.name));
 	}
 
 	pgstat_unlock_entry(entry_ref);
@@ -187,7 +187,13 @@ pgstat_fetch_replslot(NameData slotname)
 void
 pgstat_replslot_to_serialized_name_cb(const PgStatShared_Common *header, NameData *name)
 {
-	namestrcpy(name, NameStr(((PgStatShared_ReplSlot *) header)->stats.slotname));
+	namestrcpy(name, NameStr(((PgStatShared_ReplSlot *) header)->slotname));
+}
+
+void
+pgstat_replslot_set_name_cb(const PgStatShared_Common *header, NameData *name)
+{
+	namestrcpy(&((PgStatShared_ReplSlot *) header)->slotname, NameStr(*name));
 }
 
 bool
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index ad7334a0d2..530d49e5c3 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -321,7 +321,6 @@ typedef struct PgStat_StatFuncEntry
 
 typedef struct PgStat_StatReplSlotEntry
 {
-	NameData	slotname;
 	PgStat_Counter spill_txns;
 	PgStat_Counter spill_count;
 	PgStat_Counter spill_bytes;
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 40a3602855..ff07247062 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -244,6 +244,7 @@ typedef struct PgStat_KindInfo
 	 */
 	void		(*to_serialized_name) (const PgStatShared_Common *header, NameData *name);
 	bool		(*from_serialized_name) (const NameData *name, PgStat_HashKey *key);
+	void		(*set_name) (const PgStatShared_Common *header, NameData *name);
 
 	/*
 	 * For fixed-numbered statistics: Reset All.
@@ -380,6 +381,7 @@ typedef struct PgStatShared_Subscription
 typedef struct PgStatShared_ReplSlot
 {
 	PgStatShared_Common header;
+	NameData	slotname;
 	PgStat_StatReplSlotEntry stats;
 } PgStatShared_ReplSlot;
 
@@ -568,6 +570,7 @@ extern void pgstat_relation_delete_pending_cb(PgStat_EntryRef *entry_ref);
 
 extern void pgstat_replslot_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
 extern void pgstat_replslot_to_serialized_name_cb(const PgStatShared_Common *header, NameData *name);
+extern void pgstat_replslot_set_name_cb(const PgStatShared_Common *header, NameData *name);
 extern bool pgstat_replslot_from_serialized_name_cb(const NameData *name, PgStat_HashKey *key);
 
 
-- 
2.31.1

From f34c6ed510fbe4c079a0c80e9040cac77c60fd19 Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Thu, 6 Oct 2022 15:50:36 -0700
Subject: [PATCH v3] pgstat: Remove slotname from PgStat_StatReplSlotEntry

This fixes a bug where the slotname is reset as part of
pgstat_reset_replslot() subsequently causing an allocation failure in
pgstat_report_replslot(). It also is architecturally nicer, because having the
name as part of the stats isn't quite right, on account of not actually being
stats :)

As far as I can tell we actually have worked around all the dangers that lead
us to keeping the stats name part of the stats.

Author:
Reviewed-by:
Discussion: https://postgr.es/m/
Backpatch:
---
 src/include/pgstat.h                         |  2 ++
 src/include/utils/pgstat_internal.h          |  5 +--
 src/backend/utils/activity/pgstat.c          |  2 +-
 src/backend/utils/activity/pgstat_replslot.c | 36 +++++---------------
 4 files changed, 14 insertions(+), 31 deletions(-)

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index ad7334a0d21..2a85fa0369a 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -321,7 +321,9 @@ typedef struct PgStat_StatFuncEntry
 
 typedef struct PgStat_StatReplSlotEntry
 {
+#if IN_PG_15_ONLY_UNUSED
 	NameData	slotname;
+#endif
 	PgStat_Counter spill_txns;
 	PgStat_Counter spill_count;
 	PgStat_Counter spill_bytes;
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 40a36028554..627c1389e4c 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -242,7 +242,8 @@ typedef struct PgStat_KindInfo
 	/*
 	 * For variable-numbered stats with named_on_disk. Optional.
 	 */
-	void		(*to_serialized_name) (const PgStatShared_Common *header, NameData *name);
+	void		(*to_serialized_name) (const PgStat_HashKey *key,
+									   const PgStatShared_Common *header, NameData *name);
 	bool		(*from_serialized_name) (const NameData *name, PgStat_HashKey *key);
 
 	/*
@@ -567,7 +568,7 @@ extern void pgstat_relation_delete_pending_cb(PgStat_EntryRef *entry_ref);
  */
 
 extern void pgstat_replslot_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
-extern void pgstat_replslot_to_serialized_name_cb(const PgStatShared_Common *header, NameData *name);
+extern void pgstat_replslot_to_serialized_name_cb(const PgStat_HashKey *key, const PgStatShared_Common *header, NameData *name);
 extern bool pgstat_replslot_from_serialized_name_cb(const NameData *name, PgStat_HashKey *key);
 
 
diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index 609f0b1ad86..1b97597f17c 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -1367,7 +1367,7 @@ pgstat_write_statsfile(void)
 			/* stats entry identified by name on disk (e.g. slots) */
 			NameData	name;
 
-			kind_info->to_serialized_name(shstats, &name);
+			kind_info->to_serialized_name(&ps->key, shstats, &name);
 
 			fputc('N', fpout);
 			write_chunk_s(fpout, &ps->key.kind);
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index 2039ac3147f..793f26fc950 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -82,12 +82,6 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	shstatent = (PgStatShared_ReplSlot *) entry_ref->shared_stats;
 	statent = &shstatent->stats;
 
-	/*
-	 * Any mismatch should have been fixed in pgstat_create_replslot() or
-	 * pgstat_acquire_replslot().
-	 */
-	Assert(namestrcmp(&statent->slotname, NameStr(slot->data.name)) == 0);
-
 	/* Update the replication slot statistics */
 #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
 	REPLSLOT_ACC(spill_txns);
@@ -124,7 +118,6 @@ pgstat_create_replslot(ReplicationSlot *slot)
 	 * if we previously crashed after dropping a slot.
 	 */
 	memset(&shstatent->stats, 0, sizeof(shstatent->stats));
-	namestrcpy(&shstatent->stats.slotname, NameStr(slot->data.name));
 
 	pgstat_unlock_entry(entry_ref);
 }
@@ -135,27 +128,13 @@ pgstat_create_replslot(ReplicationSlot *slot)
 void
 pgstat_acquire_replslot(ReplicationSlot *slot)
 {
-	PgStat_EntryRef *entry_ref;
-	PgStatShared_ReplSlot *shstatent;
-	PgStat_StatReplSlotEntry *statent;
-
-	entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_REPLSLOT, InvalidOid,
-											ReplicationSlotIndex(slot), false);
-	shstatent = (PgStatShared_ReplSlot *) entry_ref->shared_stats;
-	statent = &shstatent->stats;
-
 	/*
-	 * NB: need to accept that there might be stats from an older slot, e.g.
-	 * if we previously crashed after dropping a slot.
+	 * XXX: I think there cannot actually be data from an older slot
+	 * here. After a crash we throw away the old stats data and if a slot is
+	 * dropped while shut down, we'll not load the slot data at startup.
 	 */
-	if (NameStr(statent->slotname)[0] == 0 ||
-		namestrcmp(&statent->slotname, NameStr(slot->data.name)) != 0)
-	{
-		memset(statent, 0, sizeof(*statent));
-		namestrcpy(&statent->slotname, NameStr(slot->data.name));
-	}
-
-	pgstat_unlock_entry(entry_ref);
+	pgstat_get_entry_ref(PGSTAT_KIND_REPLSLOT, InvalidOid,
+						 ReplicationSlotIndex(slot), false, NULL);
 }
 
 /*
@@ -185,9 +164,10 @@ pgstat_fetch_replslot(NameData slotname)
 }
 
 void
-pgstat_replslot_to_serialized_name_cb(const PgStatShared_Common *header, NameData *name)
+pgstat_replslot_to_serialized_name_cb(const PgStat_HashKey *key, const PgStatShared_Common *header, NameData *name)
 {
-	namestrcpy(name, NameStr(((PgStatShared_ReplSlot *) header)->stats.slotname));
+	/* FIXME: wrap in a slot.c function */
+	namestrcpy(name, NameStr(ReplicationSlotCtl->replication_slots[key->objoid].data.name));
 }
 
 bool
-- 
2.38.0

From 4c13dc7657fb7b9a853055b693564706847b7841 Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Fri, 7 Oct 2022 19:37:48 -0700
Subject: [PATCH v4] pgstat: Prevent stats reset from corrupting slotname by
 removing slotname

Previously PgStat_StatReplSlotEntry contained the slotname, which was mainly
used when writing out the stats during shutdown, to identify the slot in the
serialized data (at runtime the index in ReplicationSlotCtl->replication_slots
is used, but that can change during a restart). Unfortunately the slotname was
overwritten when the slot's stats were reset.

That turned out to only cause "real" problems if the slot was active during
the reset, triggering an assertion failure at the next
pgstat_report_replslot(). In other paths the stats were re-initialized during
pgstat_acquire_replslot().

Fix this by removing slotname. Instead we can get the slot's name from the
slot itself. Besides fixing a bug, this also is architecturally cleaner (a
name is not really statistics). This is safe because stats, for a slot removed
while shut down, will not be restored at startup.

In 15 the slotname is not removed, but renamed, to avoid changing the stats
format. In master, bump PGSTAT_FILE_FORMAT_ID.

This commit does not contain a test for the fix. I think this can only be
tested by a tap test starting pg_recvlogical in the background and checking
pg_recvlogical's output. That type of test is notoriously hard to be reliable,
so committing it shortly before the release is wrapped seems like a bad idea.

Reported-by: Jaime Casanova <jcasanov@systemguards.com.ec>
Author: Andres Freund <andres@anarazel.de>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/YxfagaTXUNa9ggLb@ahch-to
Backpatch: 15-, where the bug was introduced in 5891c7a8ed8f
---
 src/include/pgstat.h                         |  8 ++-
 src/include/replication/slot.h               |  1 +
 src/include/utils/pgstat_internal.h          |  5 +-
 src/backend/replication/slot.c               | 28 ++++++++++
 src/backend/utils/activity/pgstat.c          |  2 +-
 src/backend/utils/activity/pgstat_replslot.c | 56 +++++++++-----------
 6 files changed, 65 insertions(+), 35 deletions(-)

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index ad7334a0d21..b6cc9e47942 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -242,7 +242,8 @@ typedef struct PgStat_TableXactStatus
  * ------------------------------------------------------------
  */
 
-#define PGSTAT_FILE_FORMAT_ID	0x01A5BCA7
+/* FIXME: before push: only in master */
+#define PGSTAT_FILE_FORMAT_ID	0x01A5BCA8
 
 typedef struct PgStat_ArchiverStats
 {
@@ -321,7 +322,10 @@ typedef struct PgStat_StatFuncEntry
 
 typedef struct PgStat_StatReplSlotEntry
 {
-	NameData	slotname;
+	/* FIXME: perform branch specific action before push */
+#if IN_PG_15_ONLY_UNUSED
+	NameData	slotname_unused;
+#endif
 	PgStat_Counter spill_txns;
 	PgStat_Counter spill_count;
 	PgStat_Counter spill_bytes;
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 8d5e764aef5..65f2c74239d 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -218,6 +218,7 @@ extern void ReplicationSlotsDropDBSlots(Oid dboid);
 extern bool InvalidateObsoleteReplicationSlots(XLogSegNo oldestSegno);
 extern ReplicationSlot *SearchNamedReplicationSlot(const char *name, bool need_lock);
 extern int	ReplicationSlotIndex(ReplicationSlot *slot);
+extern bool ReplicationSlotName(int index, Name name);
 extern void ReplicationSlotNameForTablesync(Oid suboid, Oid relid, char *syncslotname, Size szslot);
 extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname, bool missing_ok);
 
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 40a36028554..627c1389e4c 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -242,7 +242,8 @@ typedef struct PgStat_KindInfo
 	/*
 	 * For variable-numbered stats with named_on_disk. Optional.
 	 */
-	void		(*to_serialized_name) (const PgStatShared_Common *header, NameData *name);
+	void		(*to_serialized_name) (const PgStat_HashKey *key,
+									   const PgStatShared_Common *header, NameData *name);
 	bool		(*from_serialized_name) (const NameData *name, PgStat_HashKey *key);
 
 	/*
@@ -567,7 +568,7 @@ extern void pgstat_relation_delete_pending_cb(PgStat_EntryRef *entry_ref);
  */
 
 extern void pgstat_replslot_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
-extern void pgstat_replslot_to_serialized_name_cb(const PgStatShared_Common *header, NameData *name);
+extern void pgstat_replslot_to_serialized_name_cb(const PgStat_HashKey *key, const PgStatShared_Common *header, NameData *name);
 extern bool pgstat_replslot_from_serialized_name_cb(const NameData *name, PgStat_HashKey *key);
 
 
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index e9328961dd3..d58d16e992a 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -412,6 +412,34 @@ ReplicationSlotIndex(ReplicationSlot *slot)
 	return slot - ReplicationSlotCtl->replication_slots;
 }
 
+/*
+ * If the slot at 'index' is unused, return false. Otherwise 'name' is set to
+ * the slot's name and true is returned.
+ *
+ * This likely is only useful for pgstat_replslot.c during shutdown, in other
+ * cases there are obvious TOCTOU issues.
+ */
+bool
+ReplicationSlotName(int index, Name name)
+{
+	ReplicationSlot *slot;
+	bool		found;
+
+	slot = &ReplicationSlotCtl->replication_slots[index];
+
+	/*
+	 * Ensure that the slot cannot be dropped while we copy the name. Don't
+	 * need the spinlock as the name of an existing slot cannot change.
+	 */
+	LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
+	found = slot->in_use;
+	if (slot->in_use)
+		namestrcpy(name, NameStr(slot->data.name));
+	LWLockRelease(ReplicationSlotControlLock);
+
+	return found;
+}
+
 /*
  * Find a previously created slot and mark it as used by this process.
  *
diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index 609f0b1ad86..1b97597f17c 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -1367,7 +1367,7 @@ pgstat_write_statsfile(void)
 			/* stats entry identified by name on disk (e.g. slots) */
 			NameData	name;
 
-			kind_info->to_serialized_name(shstats, &name);
+			kind_info->to_serialized_name(&ps->key, shstats, &name);
 
 			fputc('N', fpout);
 			write_chunk_s(fpout, &ps->key.kind);
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index 2039ac3147f..252d2e4e078 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -69,6 +69,10 @@ pgstat_reset_replslot(const char *name)
 
 /*
  * Report replication slot statistics.
+ *
+ * We can rely on the stats for the slot to exist and to belong to this
+ * slot. We can only get here if pgstat_create_replslot() or
+ * pgstat_acquire_replslot() have already been called.
  */
 void
 pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *repSlotStat)
@@ -82,12 +86,6 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	shstatent = (PgStatShared_ReplSlot *) entry_ref->shared_stats;
 	statent = &shstatent->stats;
 
-	/*
-	 * Any mismatch should have been fixed in pgstat_create_replslot() or
-	 * pgstat_acquire_replslot().
-	 */
-	Assert(namestrcmp(&statent->slotname, NameStr(slot->data.name)) == 0);
-
 	/* Update the replication slot statistics */
 #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
 	REPLSLOT_ACC(spill_txns);
@@ -124,38 +122,29 @@ pgstat_create_replslot(ReplicationSlot *slot)
 	 * if we previously crashed after dropping a slot.
 	 */
 	memset(&shstatent->stats, 0, sizeof(shstatent->stats));
-	namestrcpy(&shstatent->stats.slotname, NameStr(slot->data.name));
 
 	pgstat_unlock_entry(entry_ref);
 }
 
 /*
  * Report replication slot has been acquired.
+ *
+ * This guarantees that a stats entry exists during later
+ * pgstat_report_replslot() calls.
+ *
+ * If we previously crashed, no stats data exists. But if we did not crash,
+ * the stats do belong to this slot:
+ * - the stats cannot belong to a dropped slot, pgstat_drop_replslot() would
+ *   have been called
+ * - if the slot was removed while shut down,
+ *   pgstat_replslot_from_serialized_name_cb() returning false would have
+ *   caused the stats to be dropped
  */
 void
 pgstat_acquire_replslot(ReplicationSlot *slot)
 {
-	PgStat_EntryRef *entry_ref;
-	PgStatShared_ReplSlot *shstatent;
-	PgStat_StatReplSlotEntry *statent;
-
-	entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_REPLSLOT, InvalidOid,
-											ReplicationSlotIndex(slot), false);
-	shstatent = (PgStatShared_ReplSlot *) entry_ref->shared_stats;
-	statent = &shstatent->stats;
-
-	/*
-	 * NB: need to accept that there might be stats from an older slot, e.g.
-	 * if we previously crashed after dropping a slot.
-	 */
-	if (NameStr(statent->slotname)[0] == 0 ||
-		namestrcmp(&statent->slotname, NameStr(slot->data.name)) != 0)
-	{
-		memset(statent, 0, sizeof(*statent));
-		namestrcpy(&statent->slotname, NameStr(slot->data.name));
-	}
-
-	pgstat_unlock_entry(entry_ref);
+	pgstat_get_entry_ref(PGSTAT_KIND_REPLSLOT, InvalidOid,
+						 ReplicationSlotIndex(slot), true, NULL);
 }
 
 /*
@@ -185,9 +174,16 @@ pgstat_fetch_replslot(NameData slotname)
 }
 
 void
-pgstat_replslot_to_serialized_name_cb(const PgStatShared_Common *header, NameData *name)
+pgstat_replslot_to_serialized_name_cb(const PgStat_HashKey *key, const PgStatShared_Common *header, NameData *name)
 {
-	namestrcpy(name, NameStr(((PgStatShared_ReplSlot *) header)->stats.slotname));
+	/*
+	 * This is only called late during shutdown. The set of existing slots
+	 * isn't allowed to change at this point, we can assume that a slot exists
+	 * at the offset.
+	 */
+	if (!ReplicationSlotName(key->objoid, name))
+		elog(ERROR, "could not find name for replication slot index %u",
+			 key->objoid);
 }
 
 bool
-- 
2.38.0

diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index daf03ff147..513cebf2ad 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -1,8 +1,7 @@
 
 # Copyright (c) 2021-2022, PostgreSQL Global Development Group
 
-# Test replication statistics data in pg_stat_replication_slots is sane after
-# drop replication slot and restart.
+# Test replication statistics data in pg_stat_replication_slots
 use strict;
 use warnings;
 use File::Path qw(rmtree);
@@ -10,6 +9,9 @@ use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
+# Test if statistics data in pg_stat_replication_slots is sane after drop replication
+# slot and restart.
+
 # Test set-up
 my $node = PostgreSQL::Test::Cluster->new('test');
 $node->init(allows_streaming => 'logical');
@@ -118,4 +120,78 @@ $node->safe_psql('postgres',
 # shutdown
 $node->stop;
 
+# Test if resetting statistics data in pg_stat_replication_slots while decoding is
+# ongoing works correctly.
+$node = PostgreSQL::Test::Cluster->new('test2');
+$node->init(allows_streaming => 'logical');
+$node->start;
+
+$node->safe_psql('postgres', "CREATE TABLE test(i int)");
+
+# The walsender process creates and acquires the replication slot.
+my $pg_recvlogical = IPC::Run::start(
+	[
+		'pg_recvlogical',           '-S',
+		'regression_slot',          '-d',
+		$node->connstr('postgres'), '--start',
+		'--create-slot',            '--no-loop',
+		'-f',                       '-'
+	]);
+
+# Wait for the replication slot to become active.
+$node->poll_query_until('postgres',
+	"SELECT EXISTS (SELECT 1 FROM pg_replication_slots WHERE slot_name = 'regression_slot' AND active_pid IS NOT NULL)"
+) or die "slot never became active";
+
+# Reset the replication slot statistics.
+$node->safe_psql('postgres',
+	"SELECT pg_stat_reset_replication_slot('regression_slot');");
+my $result = $node->safe_psql('postgres',
+	"SELECT * FROM pg_stat_replication_slots WHERE slot_name = 'regrssion_slot'"
+);
+is($result, "", "replication slot statistics are reset");
+
+# Test if the walsender properly updates the statistics.
+$node->safe_psql('postgres', "INSERT INTO test VALUES (1)");
+$node->poll_query_until('postgres',
+	"SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'regression_slot'"
+);
+
+# Teardown the node so the statistics is removed.
+$pg_recvlogical->kill_kill;
+$node->teardown_node;
+$node->start;
+
+# Start pg_recvlogical again.
+$pg_recvlogical = IPC::Run::start(
+	[
+		'pg_recvlogical',           '-S',
+		'regression_slot',          '-d',
+		$node->connstr('postgres'), '--start',
+		'--no-loop',                '-f',
+		'-'
+	]);
+
+# Wait for the slot to become active.
+$node->poll_query_until('postgres',
+	"SELECT EXISTS (SELECT 1 FROM pg_replication_slots WHERE slot_name = 'regression_slot' AND active_pid IS NOT NULL)"
+) or die "slot never became active";
+
+# Check if the replication slot statistics have been removed.
+$result = $node->safe_psql('postgres',
+	"SELECT * FROM pg_stat_replication_slots WHERE slot_name = 'regrssion_slot'"
+);
+is($result, "", "replication slot statistics are removed");
+
+# Test if the replication slot staistics continue to be accumulated even after
+# statistics have been removed.
+$node->safe_psql('postgres', "INSERT INTO test VALUES (1)");
+$node->poll_query_until('postgres',
+	"SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'regression_slot'"
+);
+
+# shutdown
+$pg_recvlogical->kill_kill;
+$node->stop;
+
 done_testing();

diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index daf03ff147..6be3003fb0 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -1,8 +1,7 @@
 
 # Copyright (c) 2021-2022, PostgreSQL Global Development Group
 
-# Test replication statistics data in pg_stat_replication_slots is sane after
-# drop replication slot and restart.
+# Test replication statistics data in pg_stat_replication_slots
 use strict;
 use warnings;
 use File::Path qw(rmtree);
@@ -10,6 +9,9 @@ use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
+# Test if statistics data in pg_stat_replication_slots is sane after drop replication
+# slot and restart.
+
 # Test set-up
 my $node = PostgreSQL::Test::Cluster->new('test');
 $node->init(allows_streaming => 'logical');
@@ -118,4 +120,84 @@ $node->safe_psql('postgres',
 # shutdown
 $node->stop;
 
+# Test if resetting statistics data in pg_stat_replication_slots while decoding is
+# ongoing works correctly.
+
+# Start pg_recvlogical process and wait for it to become active.
+sub start_pg_recvlogical
+{
+	my ($node, $slot_name, $create_slot) = @_;
+
+	my @cmd = (
+		'pg_recvlogical', '-S', "$slot_name", '-d',
+		$node->connstr('postgres'),
+		'--start', '--no-loop', '-f', '-');
+	push @cmd, '--create-slot' if $create_slot;
+
+	# start pg_recvlogical process.
+	my $pg_recvlogical = IPC::Run::start(@cmd);
+
+	# Wait for the replication slot to become active.
+	$node->poll_query_until('postgres',
+		"SELECT EXISTS (SELECT 1 FROM pg_replication_slots WHERE slot_name = '$slot_name' AND active_pid IS NOT NULL)"
+	) or die "slot never became active";
+
+	return $pg_recvlogical;
+}
+
+$node = PostgreSQL::Test::Cluster->new('test2');
+$node->init(allows_streaming => 'logical');
+$node->start;
+$node->safe_psql('postgres', "CREATE TABLE test(i int)");
+
+# Start pg_recvlogical process. The walsender process creates and acquires
+# the replication slot.
+my $slot_name = "regression_slot";
+my $pg_recvlogical = start_pg_recvlogical($node, $slot_name, 1);
+
+# Reset the replication slot statistics.
+$node->safe_psql('postgres',
+	"SELECT pg_stat_reset_replication_slot('$slot_name');");
+my $result = $node->safe_psql('postgres',
+	"SELECT stats_reset IS NOT NULL FROM pg_stat_replication_slots WHERE slot_name = '$slot_name'"
+);
+is($result, "t", "replication slot statistics are reset");
+
+# Test if the walsender properly updates the statistics.
+$node->safe_psql('postgres', "INSERT INTO test VALUES (1)");
+$node->poll_query_until('postgres',
+	"SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = '$slot_name'"
+);
+
+# Shutdown
+$pg_recvlogical->kill_kill;
+$node->stop;
+
+# Remove the stats file and restart the server.
+$datadir = $node->data_dir;
+my $stats_file = "$datadir/pg_stat/pgstat.stat";
+unlink($stats_file)
+  or die "could not remove $stats_file";
+$node->start;
+
+# Start pg_recvlogical again.
+$pg_recvlogical = start_pg_recvlogical($node, $slot_name, 0);
+
+# Check if the replication slot statistics have been removed.
+$result = $node->safe_psql('postgres',
+	"SELECT stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$slot_name'"
+);
+is($result, "t", "replication slot statistics are removed");
+
+# Test if the replication slot statistics continue to be accumulated even
+# after statistics have been removed.
+$node->safe_psql('postgres', "INSERT INTO test VALUES (1)");
+$node->poll_query_until('postgres',
+	"SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = '$slot_name'"
+);
+
+# Shutdown
+$pg_recvlogical->kill_kill;
+$node->stop;
+
 done_testing();