commit 3f4659a8d8a390bb24fbc6f82a6add7949fbebe2
Author: Anton A. Melnikov <a.melnikov@postgrespro.ru>
Date:   Fri Jan 14 10:54:35 2022 +0300

    Fix possible fails in pg_stat_statements test via taking into account non-query wal records.

diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 082bfa8f77..bd437aefc3 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -1370,7 +1370,7 @@ pgss_store(const char *query, uint64 queryId,
 		e->counters.blk_read_time += INSTR_TIME_GET_MILLISEC(bufusage->blk_read_time);
 		e->counters.blk_write_time += INSTR_TIME_GET_MILLISEC(bufusage->blk_write_time);
 		e->counters.usage += USAGE_EXEC(total_time);
-		e->counters.wal_records += walusage->wal_records;
+		e->counters.wal_records += (walusage->wal_records - walusage->non_query_wal_recs);
 		e->counters.wal_fpi += walusage->wal_fpi;
 		e->counters.wal_bytes += walusage->wal_bytes;
 
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index 3201fcc52b..41f17ab97c 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -20,6 +20,7 @@
 #include "access/transam.h"
 #include "access/xlog.h"
 #include "catalog/catalog.h"
+#include "executor/instrument.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "storage/bufmgr.h"
@@ -208,6 +209,11 @@ heap_page_prune_opt(Relation relation, Buffer buffer)
 			ndeleted = heap_page_prune(relation, buffer, vistest, limited_xmin,
 									   limited_ts, &nnewlpdead, NULL);
 
+			/* Take into account that heap_page_prune() just generated a new
+			 * wal record with zero xl_xid that is not related to current query.
+			 */
+			pgWalUsage.non_query_wal_recs++;
+
 			/*
 			 * Report the number of tuples reclaimed to pgstats.  This is
 			 * ndeleted minus the number of newly-LP_DEAD-set items.
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index de787c3d37..e944fc3b1a 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -38,6 +38,7 @@
 #include "access/xlog.h"
 #include "access/xloginsert.h"
 #include "access/xlogutils.h"
+#include "executor/instrument.h"
 #include "miscadmin.h"
 #include "pg_trace.h"
 #include "pgstat.h"
@@ -955,6 +956,12 @@ WriteZeroPageXlogRec(int pageno)
 	XLogBeginInsert();
 	XLogRegisterData((char *) (&pageno), sizeof(int));
 	(void) XLogInsert(RM_CLOG_ID, CLOG_ZEROPAGE);
+
+	/*
+	 * Consider that a new unrelated to current query wal record
+	 * with zero xl_xid has just been created.
+	 */
+	pgWalUsage.non_query_wal_recs++;
 }
 
 /*
diff --git a/src/backend/executor/instrument.c b/src/backend/executor/instrument.c
index c5ff02a842..214fb3cc45 100644
--- a/src/backend/executor/instrument.c
+++ b/src/backend/executor/instrument.c
@@ -268,6 +268,7 @@ WalUsageAdd(WalUsage *dst, WalUsage *add)
 	dst->wal_bytes += add->wal_bytes;
 	dst->wal_records += add->wal_records;
 	dst->wal_fpi += add->wal_fpi;
+	dst->non_query_wal_recs += add->non_query_wal_recs;
 }
 
 void
@@ -276,4 +277,5 @@ WalUsageAccumDiff(WalUsage *dst, const WalUsage *add, const WalUsage *sub)
 	dst->wal_bytes += add->wal_bytes - sub->wal_bytes;
 	dst->wal_records += add->wal_records - sub->wal_records;
 	dst->wal_fpi += add->wal_fpi - sub->wal_fpi;
+	dst->non_query_wal_recs += add->non_query_wal_recs - sub->non_query_wal_recs;
 }
diff --git a/src/include/executor/instrument.h b/src/include/executor/instrument.h
index 1b7157bdd1..0d83f37a3c 100644
--- a/src/include/executor/instrument.h
+++ b/src/include/executor/instrument.h
@@ -49,6 +49,11 @@ typedef struct WalUsage
 	int64		wal_records;	/* # of WAL records produced */
 	int64		wal_fpi;		/* # of WAL full page images produced */
 	uint64		wal_bytes;		/* size of WAL records produced */
+	/*
+	 * Number of WAL records unrelated to current query. In particular due to
+	 * heap_page_prune_opt() or WriteZeroPageXlogRec().
+	 */
+	int64		non_query_wal_recs;
 } WalUsage;
 
 /* Flag bits included in InstrAlloc's instrument_options bitmask */