Remove read/sync fields from pg_stat_wal and GUC track_wal_io_timing

The four following attributes are removed from pg_stat_wal:
* wal_write
* wal_sync
* wal_write_time
* wal_sync_time

a051e71e28a1 has added an equivalent of this information in pg_stat_io
with more granularity as this now spreads across the backend types, IO
context and IO objects.  So, keeping the same information in pg_stat_wal
has little benefits.

Another benefit of this commit is the removal of PendingWalStats,
simplifying an upcoming patch to add per-backend WAL statistics, which
already support IO statistics and which have access to the write/sync
stats data of WAL.

The GUC track_wal_io_timing, that was used to enable or disable the
aggregation of the write and sync timings for WAL, is also removed.
pgstat_prepare_io_time() is simplified.

Bump catalog version.
Bump PGSTAT_FILE_FORMAT_ID, due to the update of PgStat_WalStats.

Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/Z7RkQ0EfYaqqjgz/@ip-10-97-1-34.eu-west-3.compute.internal

1 files changed, 2 insertions, 30 deletions

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 53f2a8458e6..fc651d03cf9 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -212,7 +212,7 @@ typedef struct PgStat_TableXactStatus
  * ------------------------------------------------------------
  */
 
-#define PGSTAT_FILE_FORMAT_ID	0x01A5BCB3
+#define PGSTAT_FILE_FORMAT_ID	0x01A5BCB4
 
 typedef struct PgStat_ArchiverStats
 {
@@ -480,29 +480,10 @@ typedef struct PgStat_WalStats
 	PgStat_Counter wal_fpi;
 	uint64		wal_bytes;
 	PgStat_Counter wal_buffers_full;
-	PgStat_Counter wal_write;
-	PgStat_Counter wal_sync;
-	PgStat_Counter wal_write_time;
-	PgStat_Counter wal_sync_time;
 	TimestampTz stat_reset_timestamp;
 } PgStat_WalStats;
 
 /*
- * This struct stores wal-related durations as instr_time, which makes it
- * cheaper and easier to accumulate them, by not requiring type
- * conversions. During stats flush instr_time will be converted into
- * microseconds.
- */
-typedef struct PgStat_PendingWalStats
-{
-	PgStat_Counter wal_write;
-	PgStat_Counter wal_sync;
-	instr_time	wal_write_time;
-	instr_time	wal_sync_time;
-} PgStat_PendingWalStats;
-
-
-/*
  * Functions in pgstat.c
  */
 
@@ -583,7 +564,7 @@ extern bool pgstat_bktype_io_stats_valid(PgStat_BktypeIO *backend_io,
 										 BackendType bktype);
 extern void pgstat_count_io_op(IOObject io_object, IOContext io_context,
 							   IOOp io_op, uint32 cnt, uint64 bytes);
-extern instr_time pgstat_prepare_io_time(bool track_io_guc);
+extern instr_time pgstat_prepare_io_time(void);
 extern void pgstat_count_io_op_time(IOObject io_object, IOContext io_context,
 									IOOp io_op, instr_time start_time,
 									uint32 cnt, uint64 bytes);
@@ -834,13 +815,4 @@ extern PGDLLIMPORT PgStat_Counter pgStatTransactionIdleTime;
 /* updated by the traffic cop and in errfinish() */
 extern PGDLLIMPORT SessionEndType pgStatSessionEndCause;
 
-
-/*
- * Variables in pgstat_wal.c
- */
-
-/* updated directly by backends and background processes */
-extern PGDLLIMPORT PgStat_PendingWalStats PendingWalStats;
-
-
 #endif							/* PGSTAT_H */