v2-0001-Add-wal_fpi_bytes-to-pg_stat_wal.patch
application/octet-stream
Filename: v2-0001-Add-wal_fpi_bytes-to-pg_stat_wal.patch
Type: application/octet-stream
Part: 0
From ff10d7684ead9efd0b7f6ff03b68d598917c7c5c Mon Sep 17 00:00:00 2001
From: Shinya Kato <shinya11.kato@gmail.com>
Date: Sat, 18 Oct 2025 16:27:32 +0900
Subject: [PATCH v2 1/2] Add wal_fpi_bytes to pg_stat_wal
Track the total size of full-page images in WAL statistics so that the
effect of wal_compression can be monitored. XLogRecordAssemble now
increments a new wal_fpi_bytes counter in WalUsage, and the backend and
shared WAL stats paths flush that value alongside the existing counters.
Expose the counter through pg_stat_get_wal(), pg_stat_get_backend_wal(),
pg_stat_wal.
Author: Shinya Kato <shinya11.kato@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discusssion: https://postgr.es/m/CAOzEurQtZEAfg6P0kU3Wa-f9BWQOi0RzJEMPN56wNTOmJLmfaQ@mail.gmail.com
---
doc/src/sgml/monitoring.sgml | 11 +++++++++++
src/backend/access/transam/xloginsert.c | 6 ++++++
src/backend/catalog/system_views.sql | 3 ++-
src/backend/utils/activity/pgstat_backend.c | 1 +
src/backend/utils/activity/pgstat_wal.c | 1 +
src/backend/utils/adt/pgstatfuncs.c | 10 +++++++++-
src/include/catalog/pg_proc.dat | 12 ++++++------
src/include/executor/instrument.h | 1 +
src/include/pgstat.h | 1 +
src/test/regress/expected/rules.out | 5 +++--
10 files changed, 41 insertions(+), 10 deletions(-)
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index d5f0fb7ba7c..0db378ee99e 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -3340,6 +3340,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
Time at which these statistics were last reset
</para></entry>
</row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>wal_fpi_bytes</structfield> <type>numeric</type>
+ </para>
+ <para>
+ Total amount of WAL full page images in bytes; if
+ <varname>wal_compression</varname> is enabled, this reflects the
+ compressed size
+ </para></entry>
+ </row>
</tbody>
</tgroup>
</table>
diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c
index 496e0fa4ac6..b3abf386f80 100644
--- a/src/backend/access/transam/xloginsert.c
+++ b/src/backend/access/transam/xloginsert.c
@@ -33,12 +33,14 @@
#include "access/xloginsert.h"
#include "catalog/pg_control.h"
#include "common/pg_lzcompress.h"
+#include "executor/instrument.h"
#include "miscadmin.h"
#include "pg_trace.h"
#include "replication/origin.h"
#include "storage/bufmgr.h"
#include "storage/proc.h"
#include "utils/memutils.h"
+#include "utils/pgstat_internal.h"
/*
* Guess the maximum buffer size required to store a compressed version of
@@ -796,6 +798,10 @@ XLogRecordAssemble(RmgrId rmid, uint8 info,
}
total_len += bimg.length;
+
+ /* Track the WAL full page images in bytes */
+ pgWalUsage.wal_fpi_bytes += bimg.length;
+ pgstat_report_fixed = true;
}
if (needs_data)
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 823776c1498..d7f149f9328 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1222,7 +1222,8 @@ CREATE VIEW pg_stat_wal AS
w.wal_fpi,
w.wal_bytes,
w.wal_buffers_full,
- w.stats_reset
+ w.stats_reset,
+ w.wal_fpi_bytes
FROM pg_stat_get_wal() w;
CREATE VIEW pg_stat_progress_analyze AS
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index a864ae8e6a6..199ba2cc17a 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -252,6 +252,7 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
WALSTAT_ACC(wal_records, wal_usage_diff);
WALSTAT_ACC(wal_fpi, wal_usage_diff);
WALSTAT_ACC(wal_bytes, wal_usage_diff);
+ WALSTAT_ACC(wal_fpi_bytes, wal_usage_diff);
#undef WALSTAT_ACC
/*
diff --git a/src/backend/utils/activity/pgstat_wal.c b/src/backend/utils/activity/pgstat_wal.c
index 0d04480d2f6..4d796c5e790 100644
--- a/src/backend/utils/activity/pgstat_wal.c
+++ b/src/backend/utils/activity/pgstat_wal.c
@@ -122,6 +122,7 @@ pgstat_wal_flush_cb(bool nowait)
WALSTAT_ACC(wal_fpi, wal_usage_diff);
WALSTAT_ACC(wal_bytes, wal_usage_diff);
WALSTAT_ACC(wal_buffers_full, wal_usage_diff);
+ WALSTAT_ACC(wal_fpi_bytes, wal_usage_diff);
#undef WALSTAT_ACC
LWLockRelease(&stats_shmem->lock);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 1fe33df2756..21efc010334 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1637,7 +1637,7 @@ static Datum
pg_stat_wal_build_tuple(PgStat_WalCounters wal_counters,
TimestampTz stat_reset_timestamp)
{
-#define PG_STAT_WAL_COLS 5
+#define PG_STAT_WAL_COLS 6
TupleDesc tupdesc;
Datum values[PG_STAT_WAL_COLS] = {0};
bool nulls[PG_STAT_WAL_COLS] = {0};
@@ -1655,6 +1655,8 @@ pg_stat_wal_build_tuple(PgStat_WalCounters wal_counters,
INT8OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 5, "stats_reset",
TIMESTAMPTZOID, -1, 0);
+ TupleDescInitEntry(tupdesc, (AttrNumber) 6, "wal_fpi_bytes",
+ NUMERICOID, -1, 0);
BlessTupleDesc(tupdesc);
@@ -1676,6 +1678,12 @@ pg_stat_wal_build_tuple(PgStat_WalCounters wal_counters,
else
nulls[4] = true;
+ snprintf(buf, sizeof buf, UINT64_FORMAT, wal_counters.wal_fpi_bytes);
+ values[5] = DirectFunctionCall3(numeric_in,
+ CStringGetDatum(buf),
+ ObjectIdGetDatum(0),
+ Int32GetDatum(-1));
+
/* Returns the record as Datum */
PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
}
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index eecb43ec6f0..952a51969b3 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6029,16 +6029,16 @@
{ oid => '1136', descr => 'statistics: information about WAL activity',
proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
proparallel => 'r', prorettype => 'record', proargtypes => '',
- proallargtypes => '{int8,int8,numeric,int8,timestamptz}',
- proargmodes => '{o,o,o,o,o}',
- proargnames => '{wal_records,wal_fpi,wal_bytes,wal_buffers_full,stats_reset}',
+ proallargtypes => '{int8,int8,numeric,int8,timestamptz,numeric}',
+ proargmodes => '{o,o,o,o,o,o}',
+ proargnames => '{wal_records,wal_fpi,wal_bytes,wal_buffers_full,stats_reset,wal_fpi_bytes}',
prosrc => 'pg_stat_get_wal' },
{ oid => '6313', descr => 'statistics: backend WAL activity',
proname => 'pg_stat_get_backend_wal', provolatile => 'v', proparallel => 'r',
prorettype => 'record', proargtypes => 'int4',
- proallargtypes => '{int4,int8,int8,numeric,int8,timestamptz}',
- proargmodes => '{i,o,o,o,o,o}',
- proargnames => '{backend_pid,wal_records,wal_fpi,wal_bytes,wal_buffers_full,stats_reset}',
+ proallargtypes => '{int4,int8,int8,numeric,int8,timestamptz,numeric}',
+ proargmodes => '{i,o,o,o,o,o,o}',
+ proargnames => '{backend_pid,wal_records,wal_fpi,wal_bytes,wal_buffers_full,stats_reset,wal_fpi_bytes}',
prosrc => 'pg_stat_get_backend_wal' },
{ oid => '6248', descr => 'statistics: information about WAL prefetching',
proname => 'pg_stat_get_recovery_prefetch', prorows => '1', proretset => 't',
diff --git a/src/include/executor/instrument.h b/src/include/executor/instrument.h
index 03653ab6c6c..7eb02833fad 100644
--- a/src/include/executor/instrument.h
+++ b/src/include/executor/instrument.h
@@ -54,6 +54,7 @@ typedef struct WalUsage
int64 wal_fpi; /* # of WAL full page images produced */
uint64 wal_bytes; /* size of WAL records produced */
int64 wal_buffers_full; /* # of times the WAL buffers became full */
+ uint64 wal_fpi_bytes; /* size of FPIs after compression */
} WalUsage;
/* Flag bits included in InstrAlloc's instrument_options bitmask */
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index bc8077cbae6..9c2d44bab89 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -473,6 +473,7 @@ typedef struct PgStat_WalCounters
PgStat_Counter wal_records;
PgStat_Counter wal_fpi;
uint64 wal_bytes;
+ uint64 wal_fpi_bytes;
PgStat_Counter wal_buffers_full;
} PgStat_WalCounters;
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 16753b2e4c0..6c3d78e96aa 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2307,8 +2307,9 @@ pg_stat_wal| SELECT wal_records,
wal_fpi,
wal_bytes,
wal_buffers_full,
- stats_reset
- FROM pg_stat_get_wal() w(wal_records, wal_fpi, wal_bytes, wal_buffers_full, stats_reset);
+ stats_reset,
+ wal_fpi_bytes
+ FROM pg_stat_get_wal() w(wal_records, wal_fpi, wal_bytes, wal_buffers_full, stats_reset, wal_fpi_bytes);
pg_stat_wal_receiver| SELECT pid,
status,
receive_start_lsn,
--
2.47.3