On 2020-09-26 19:18, Amit Kapila wrote:
On Fri, Sep 25, 2020 at 11:06 PM Fujii Masao
<masao.fu...@oss.nttdata.com> wrote:
On 2020/09/25 12:06, Masahiro Ikeda wrote:
> On 2020-09-18 11:11, Kyotaro Horiguchi wrote:
>> At Fri, 18 Sep 2020 09:40:11 +0900, Masahiro Ikeda
>> <ikeda...@oss.nttdata.com> wrote in
>>> Thanks. I confirmed that it causes HOT pruning or killing of
>>> dead index tuple if DecodeCommit() is called.
>>>
>>> As you said, DecodeCommit() may access the system table.
>> ...
>>> The wals are generated only when logical replication is performed.
>>> So, I added pgstat_send_wal() in XLogSendLogical().
>>>
>>> But, I concerned that it causes poor performance
>>> since pgstat_send_wal() is called per wal record,
>>
>> I think that's too frequent. If we want to send any stats to the
>> collector, it is usually done at commit time using
>> pgstat_report_stat(), and the function avoids sending stats too
>> frequently. For logrep-worker, apply_handle_commit() is calling it. It
>> seems to be the place if we want to send the wal stats. Or it may be
>> better to call pgstat_send_wal() via pgstat_report_stat(), like
>> pg_stat_slru().
>
> Thanks for your comments.
> Since I changed to use pgstat_report_stat() and DecodeCommit() is calling it,
> the frequency to send statistics is not so high.
On second thought, it's strange to include this change in pg_stat_wal
patch.
Because pgstat_report_stat() sends various stats and that change would
affect not only pg_stat_wal but also other stats views. That is, if we
really
want to make some processes call pgstat_report_stat() newly, which
should be implemented as a separate patch. But I'm not sure how useful
this change is because probably the stats are almost negligibly small
in those processes.
This thought seems valid for pgstat_send_wal(). I changed the thought
and am inclined to be ok not to call pgstat_send_wal() in some
background
processes that are very unlikely to generate WAL.
OK, I removed to pgstat_report_stat() for autovaccum launcher,
logrep-worker and logrep-launcher.
This makes sense to me. I think even if such background processes have
to write WAL due to wal_buffers, it will be accounted next time the
backend sends the stats.
Thanks for your comments.
IIUC, since each process counts WalStats.m_wal_buffers_full,
backend can't send the counter which other background processes have to
write WAL due to wal_buffers.
Although we can't track all WAL activity, the impact on the statistics
is minimal so we can ignore it.
One minor point, don't we need to reset the counter
WalStats.m_wal_buffers_full once we sent the stats, otherwise the same
stats will be accounted multiple times.
Now, the counter is reset in pgstat_send_wal.
Isn't it enough?
The checkpointer doesn't seem to call pgstat_report_stat() currently,
but since there is a possibility to send wal statistics, I added
pgstat_report_stat().
IMO it's better to call pgstat_send_wal() in the checkpointer, instead,
because of the above reason.
Ok, I changed.
Thanks for updating the patch! I'd like to share my review comments.
+ <xref linkend="monitoring-pg-stat-wal-view"/> for details.
Like the description for pg_stat_bgwriter, <link> tag should be used
instead of <xref>.
Thanks, fixed.
+ <para>
+ Number of WAL writes when the <xref linkend="guc-wal-buffers"/>
are full
+ </para></entry>
I prefer the following description. Thought?
"Number of times WAL data was written to the disk because wal_buffers
got full"
Ok, I changed.
+ the <structname>pg_stat_archiver</structname> view ,or
<literal>wal</literal>
A comma should be just after "view" (not just before "or").
Sorry, anyway I think a comma is not necessary.
I removed it.
+/*
+ * WAL global statistics counter.
+ * This counter is incremented by both each backend and background.
+ * And then, sent to the stat collector process.
+ */
+PgStat_MsgWal WalStats;
What about merging the comments for BgWriterStats and WalStats into
one because they are almost the same? For example,
-------------------------------
/*
* BgWriter and WAL global statistics counters.
* Stored directly in a stats message structure so they can be sent
* without needing to copy things around. We assume these init to
zeroes.
*/
PgStat_MsgBgWriter BgWriterStats;
PgStat_MsgWal WalStats;
-------------------------------
BTW, originally there was the comment "(unused in other processes)"
for BgWriterStats. But it seems not true, so I removed it from
the above example.
Thanks, I changed.
+ rc = fwrite(&walStats, sizeof(walStats), 1, fpout);
+ (void) rc; /* we'll check for
error with ferror */
Since the patch changes the pgstat file format,
PGSTAT_FILE_FORMAT_ID should also be changed?
Sorry about that.
I incremented PGSTAT_FILE_FORMAT_ID by +1.
- * Clear out global and archiver statistics so they start from zero
in
+ * Clear out global, archiver and wal statistics so they start from
zero in
This is not the issue of this patch, but isn't it better to mention
also SLRU stats here? That is, what about "Clear out global, archiver,
WAL and SLRU statistics so they start from zero in"?
Thanks, I changed.
I found "wal statistics" and "wal stats" in some comments in the patch,
but isn't it better to use "WAL statistics" and "WAL stats", instead,
if there is no special reason to use lowercase?
OK. I fixed it.
+ /*
+ * Read wal stats struct
+ */
+ if (fread(&walStats, 1, sizeof(walStats), fpin) != sizeof(walStats))
In pgstat_read_db_statsfile_timestamp(), the local variable myWalStats
should be declared and be used to store the WAL stats read via fread(),
instead.
Thanks, I changed it to declare myWalStats.
+{ oid => '1136', descr => 'statistics: number of WAL writes when the
wal buffers are full',
If we change the description of wal_buffers_full column in the document
as I proposed, we should also use the proposed description here.
OK, I fixed it.
+{ oid => '1137', descr => 'statistics: last reset for the walwriter',
"the walwriter" should be "WAL" or "WAL activity", etc?
Thanks, I fixed it.
+ * PgStat_MsgWal Sent by each backend and background
workers to
update WAL statistics.
If your intention here is to mention background processes like
checkpointer,
"each backend and background workers" should be "backends and
background
processes"?
Thanks, I fixed it.
+ PgStat_Counter m_wal_buffers_full; /* number of WAL write caused by
full of WAL buffers */
I don't think this comment is necessary.
OK, I removed.
+ PgStat_Counter wal_buffers_full; /* number of WAL write caused by
full of WAL buffers */
+ TimestampTz stat_reset_timestamp; /* last time when the stats reset
*/
I don't think these comments are necessary.
OK, I removed
+/*
+ * WAL writes statistics counter is updated by backend and background
workers
Same as above.
I fixed it.
Regards,
--
Masahiro Ikeda
NTT DATA CORPORATION
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 4e0193a967..e50710bdbd 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -424,6 +424,14 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry><structname>pg_stat_wal</structname><indexterm><primary>pg_stat_wal</primary></indexterm></entry>
+ <entry>One row only, showing statistics about WAL activity. See
+ <link linkend="monitoring-pg-stat-wal-view">
+ <structname>pg_stat_wal</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_database</structname><indexterm><primary>pg_stat_database</primary></indexterm></entry>
<entry>One row per database, showing database-wide statistics. See
@@ -3280,6 +3288,56 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
</sect2>
+ <sect2 id="monitoring-pg-stat-wal-view">
+ <title><structname>pg_stat_wal</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_wal</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_wal</structname> view will always have a
+ single row, containing data about WAL activity of the cluster.
+ </para>
+
+ <table id="pg-stat-wal-view" xreflabel="pg_stat_wal">
+ <title><structname>pg_stat_wal</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>wal_buffers_full</structfield> <type>bigint</type>
+ </para>
+ <para>
+ Number of times WAL data was written to the disk because wal_buffers got full
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+</sect2>
+
<sect2 id="monitoring-pg-stat-database-view">
<title><structname>pg_stat_database</structname></title>
@@ -4668,8 +4726,9 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
argument. The argument can be <literal>bgwriter</literal> to reset
all the counters shown in
the <structname>pg_stat_bgwriter</structname>
- view, or <literal>archiver</literal> to reset all the counters shown in
- the <structname>pg_stat_archiver</structname> view.
+ view, <literal>archiver</literal> to reset all the counters shown in
+ the <structname>pg_stat_archiver</structname> view or <literal>wal</literal>
+ to reset all the counters shown in the <structname>pg_stat_wal</structname> view.
</para>
<para>
This function is restricted to superusers by default, but other users
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 79a77ebbfe..64403690da 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2195,6 +2195,7 @@ AdvanceXLInsertBuffer(XLogRecPtr upto, bool opportunistic)
WriteRqst.Flush = 0;
XLogWrite(WriteRqst, false);
LWLockRelease(WALWriteLock);
+ WalStats.m_wal_buffers_full++;
TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY_DONE();
}
/* Re-acquire WALBufMappingLock and retry */
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index ed4f3f142d..643445c189 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -979,6 +979,11 @@ CREATE VIEW pg_stat_bgwriter AS
pg_stat_get_buf_alloc() AS buffers_alloc,
pg_stat_get_bgwriter_stat_reset_time() AS stats_reset;
+CREATE VIEW pg_stat_wal AS
+ SELECT
+ pg_stat_get_wal_buffers_full() AS wal_buffers_full,
+ pg_stat_get_wal_stat_reset_time() AS stats_reset;
+
CREATE VIEW pg_stat_progress_analyze AS
SELECT
S.pid AS pid, S.datid AS datid, D.datname AS datname,
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index 3e7dcd4f76..429c8010ef 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -504,6 +504,9 @@ CheckpointerMain(void)
*/
pgstat_send_bgwriter();
+ /* Send WAL statistics to the stats collector. */
+ pgstat_send_wal();
+
/*
* If any checkpoint flags have been set, redo the loop to handle the
* checkpoint without sleeping.
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index e6be2b7836..9d8a435304 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -135,11 +135,12 @@ char *pgstat_stat_filename = NULL;
char *pgstat_stat_tmpname = NULL;
/*
- * BgWriter global statistics counters (unused in other processes).
- * Stored directly in a stats message structure so it can be sent
- * without needing to copy things around. We assume this inits to zeroes.
+ * BgWriter and WAL global statistics counters.
+ * Stored directly in a stats message structure so they can be sent
+ * without needing to copy things around. We assume these init to zeroes.
*/
PgStat_MsgBgWriter BgWriterStats;
+PgStat_MsgWal WalStats;
/*
* List of SLRU names that we keep stats for. There is no central registry of
@@ -281,6 +282,7 @@ static int localNumBackends = 0;
*/
static PgStat_ArchiverStats archiverStats;
static PgStat_GlobalStats globalStats;
+static PgStat_WalStats walStats;
static PgStat_SLRUStats slruStats[SLRU_NUM_ELEMENTS];
/*
@@ -353,6 +355,7 @@ static void pgstat_recv_vacuum(PgStat_MsgVacuum *msg, int len);
static void pgstat_recv_analyze(PgStat_MsgAnalyze *msg, int len);
static void pgstat_recv_archiver(PgStat_MsgArchiver *msg, int len);
static void pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len);
+static void pgstat_recv_wal(PgStat_MsgWal *msg, int len);
static void pgstat_recv_slru(PgStat_MsgSLRU *msg, int len);
static void pgstat_recv_funcstat(PgStat_MsgFuncstat *msg, int len);
static void pgstat_recv_funcpurge(PgStat_MsgFuncpurge *msg, int len);
@@ -938,6 +941,9 @@ pgstat_report_stat(bool force)
/* Now, send function statistics */
pgstat_send_funcstats();
+ /* Send WAL statistics */
+ pgstat_send_wal();
+
/* Finally send SLRU statistics */
pgstat_send_slru();
}
@@ -1370,11 +1376,13 @@ pgstat_reset_shared_counters(const char *target)
msg.m_resettarget = RESET_ARCHIVER;
else if (strcmp(target, "bgwriter") == 0)
msg.m_resettarget = RESET_BGWRITER;
+ else if (strcmp(target, "wal") == 0)
+ msg.m_resettarget = RESET_WAL;
else
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unrecognized reset target: \"%s\"", target),
- errhint("Target must be \"archiver\" or \"bgwriter\".")));
+ errhint("Target must be \"archiver\", \"bgwriter\" or \"wal\".")));
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RESETSHAREDCOUNTER);
pgstat_send(&msg, sizeof(msg));
@@ -2674,6 +2682,21 @@ pgstat_fetch_global(void)
return &globalStats;
}
+/*
+ * ---------
+ * pgstat_fetch_stat_wal() -
+ *
+ * Support function for the SQL-callable pgstat* functions. Returns
+ * a pointer to the WAL statistics struct.
+ * ---------
+ */
+PgStat_WalStats *
+pgstat_fetch_stat_wal(void)
+{
+ backend_read_statsfile();
+
+ return &walStats;
+}
/*
* ---------
@@ -4419,6 +4442,38 @@ pgstat_send_bgwriter(void)
MemSet(&BgWriterStats, 0, sizeof(BgWriterStats));
}
+/* ----------
+ * pgstat_send_wal() -
+ *
+ * Send WAL statistics to the collector
+ * ----------
+ */
+void
+pgstat_send_wal(void)
+{
+ /* We assume this initializes to zeroes */
+ static const PgStat_MsgWal all_zeroes;
+
+ /*
+ * This function can be called even if nothing at all has happened. In
+ * this case, avoid sending a completely empty message to the stats
+ * collector.
+ */
+ if (memcmp(&WalStats, &all_zeroes, sizeof(PgStat_MsgWal)) == 0)
+ return;
+
+ /*
+ * Prepare and send the message
+ */
+ pgstat_setheader(&WalStats.m_hdr, PGSTAT_MTYPE_WAL);
+ pgstat_send(&WalStats, sizeof(WalStats));
+
+ /*
+ * Clear out the statistics buffer, so it can be re-used.
+ */
+ MemSet(&WalStats, 0, sizeof(WalStats));
+}
+
/* ----------
* pgstat_send_slru() -
*
@@ -4658,6 +4713,10 @@ PgstatCollectorMain(int argc, char *argv[])
pgstat_recv_bgwriter(&msg.msg_bgwriter, len);
break;
+ case PGSTAT_MTYPE_WAL:
+ pgstat_recv_wal(&msg.msg_wal, len);
+ break;
+
case PGSTAT_MTYPE_SLRU:
pgstat_recv_slru(&msg.msg_slru, len);
break;
@@ -4927,6 +4986,12 @@ pgstat_write_statsfiles(bool permanent, bool allDbs)
rc = fwrite(&archiverStats, sizeof(archiverStats), 1, fpout);
(void) rc; /* we'll check for error with ferror */
+ /*
+ * Write WAL stats struct
+ */
+ rc = fwrite(&walStats, sizeof(walStats), 1, fpout);
+ (void) rc; /* we'll check for error with ferror */
+
/*
* Write SLRU stats struct
*/
@@ -5186,11 +5251,12 @@ pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep)
HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
/*
- * Clear out global and archiver statistics so they start from zero in
+ * Clear out global, archiver, WAL and SLRU statistics so they start from zero in
* case we can't load an existing statsfile.
*/
memset(&globalStats, 0, sizeof(globalStats));
memset(&archiverStats, 0, sizeof(archiverStats));
+ memset(&walStats, 0, sizeof(walStats));
memset(&slruStats, 0, sizeof(slruStats));
/*
@@ -5199,6 +5265,7 @@ pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep)
*/
globalStats.stat_reset_timestamp = GetCurrentTimestamp();
archiverStats.stat_reset_timestamp = globalStats.stat_reset_timestamp;
+ walStats.stat_reset_timestamp = globalStats.stat_reset_timestamp;
/*
* Set the same reset timestamp for all SLRU items too.
@@ -5268,6 +5335,17 @@ pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep)
goto done;
}
+ /*
+ * Read WAL stats struct
+ */
+ if (fread(&walStats, 1, sizeof(walStats), fpin) != sizeof(walStats))
+ {
+ ereport(pgStatRunningInCollector ? LOG : WARNING,
+ (errmsg("corrupted statistics file \"%s\"", statfile)));
+ memset(&walStats, 0, sizeof(walStats));
+ goto done;
+ }
+
/*
* Read SLRU stats struct
*/
@@ -5578,6 +5656,7 @@ pgstat_read_db_statsfile_timestamp(Oid databaseid, bool permanent,
PgStat_StatDBEntry dbentry;
PgStat_GlobalStats myGlobalStats;
PgStat_ArchiverStats myArchiverStats;
+ PgStat_WalStats myWalStats;
PgStat_SLRUStats mySLRUStats[SLRU_NUM_ELEMENTS];
FILE *fpin;
int32 format_id;
@@ -5633,6 +5712,17 @@ pgstat_read_db_statsfile_timestamp(Oid databaseid, bool permanent,
return false;
}
+ /*
+ * Read WAL stats struct
+ */
+ if (fread(&myWalStats, 1, sizeof(myWalStats), fpin) != sizeof(myWalStats))
+ {
+ ereport(pgStatRunningInCollector ? LOG : WARNING,
+ (errmsg("corrupted statistics file \"%s\"", statfile)));
+ FreeFile(fpin);
+ return false;
+ }
+
/*
* Read SLRU stats struct
*/
@@ -6213,6 +6303,12 @@ pgstat_recv_resetsharedcounter(PgStat_MsgResetsharedcounter *msg, int len)
memset(&archiverStats, 0, sizeof(archiverStats));
archiverStats.stat_reset_timestamp = GetCurrentTimestamp();
}
+ else if (msg->m_resettarget == RESET_WAL)
+ {
+ /* Reset the WAL statistics for the cluster. */
+ memset(&walStats, 0, sizeof(walStats));
+ walStats.stat_reset_timestamp = GetCurrentTimestamp();
+ }
/*
* Presumably the sender of this message validated the target, don't
@@ -6427,6 +6523,18 @@ pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len)
globalStats.buf_alloc += msg->m_buf_alloc;
}
+/* ----------
+ * pgstat_recv_wal() -
+ *
+ * Process a WAL message.
+ * ----------
+ */
+static void
+pgstat_recv_wal(PgStat_MsgWal *msg, int len)
+{
+ walStats.wal_buffers_full += msg->m_wal_buffers_full;
+}
+
/* ----------
* pgstat_recv_slru() -
*
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 95738a4e34..aa41330796 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1697,6 +1697,18 @@ pg_stat_get_buf_alloc(PG_FUNCTION_ARGS)
PG_RETURN_INT64(pgstat_fetch_global()->buf_alloc);
}
+Datum
+pg_stat_get_wal_buffers_full(PG_FUNCTION_ARGS)
+{
+ PG_RETURN_INT64(pgstat_fetch_stat_wal()->wal_buffers_full);
+}
+
+Datum
+pg_stat_get_wal_stat_reset_time(PG_FUNCTION_ARGS)
+{
+ PG_RETURN_TIMESTAMPTZ(pgstat_fetch_stat_wal()->stat_reset_timestamp);
+}
+
/*
* Returns statistics of SLRU caches.
*/
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index f48f5fb4d9..e65e0fc64f 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5481,6 +5481,14 @@
proname => 'pg_stat_get_buf_alloc', provolatile => 's', proparallel => 'r',
prorettype => 'int8', proargtypes => '', prosrc => 'pg_stat_get_buf_alloc' },
+{ oid => '1136', descr => 'statistics: Number of times WAL data was written to the disk because wal_buffers got full',
+ proname => 'pg_stat_get_wal_buffers_full', provolatile => 's', proparallel => 'r',
+ prorettype => 'int8', proargtypes => '', prosrc => 'pg_stat_get_wal_buffers_full' },
+{ oid => '1137', descr => 'statistics: last reset for WAL activity',
+ proname => 'pg_stat_get_wal_stat_reset_time', provolatile => 's',
+ proparallel => 'r', prorettype => 'timestamptz', proargtypes => '',
+ prosrc => 'pg_stat_get_wal_stat_reset_time' },
+
{ oid => '2306', descr => 'statistics: information about SLRU caches',
proname => 'pg_stat_get_slru', prorows => '100', proisstrict => 'f',
proretset => 't', provolatile => 's', proparallel => 'r',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0dfbac46b4..f7ddf17564 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -61,6 +61,7 @@ typedef enum StatMsgType
PGSTAT_MTYPE_ANALYZE,
PGSTAT_MTYPE_ARCHIVER,
PGSTAT_MTYPE_BGWRITER,
+ PGSTAT_MTYPE_WAL,
PGSTAT_MTYPE_SLRU,
PGSTAT_MTYPE_FUNCSTAT,
PGSTAT_MTYPE_FUNCPURGE,
@@ -122,7 +123,8 @@ typedef struct PgStat_TableCounts
typedef enum PgStat_Shared_Reset_Target
{
RESET_ARCHIVER,
- RESET_BGWRITER
+ RESET_BGWRITER,
+ RESET_WAL
} PgStat_Shared_Reset_Target;
/* Possible object types for resetting single counters */
@@ -436,6 +438,16 @@ typedef struct PgStat_MsgBgWriter
PgStat_Counter m_checkpoint_sync_time;
} PgStat_MsgBgWriter;
+/* ----------
+ * PgStat_MsgWal Sent by backends and background processes to update WAL statistics.
+ * ----------
+ */
+typedef struct PgStat_MsgWal
+{
+ PgStat_MsgHdr m_hdr;
+ PgStat_Counter m_wal_buffers_full;
+} PgStat_MsgWal;
+
/* ----------
* PgStat_MsgSLRU Sent by a backend to update SLRU statistics.
* ----------
@@ -596,6 +608,7 @@ typedef union PgStat_Msg
PgStat_MsgAnalyze msg_analyze;
PgStat_MsgArchiver msg_archiver;
PgStat_MsgBgWriter msg_bgwriter;
+ PgStat_MsgWal msg_wal;
PgStat_MsgSLRU msg_slru;
PgStat_MsgFuncstat msg_funcstat;
PgStat_MsgFuncpurge msg_funcpurge;
@@ -614,7 +627,7 @@ typedef union PgStat_Msg
* ------------------------------------------------------------
*/
-#define PGSTAT_FILE_FORMAT_ID 0x01A5BC9D
+#define PGSTAT_FILE_FORMAT_ID 0x01A5BC9E
/* ----------
* PgStat_StatDBEntry The collector's data per database
@@ -745,6 +758,15 @@ typedef struct PgStat_GlobalStats
TimestampTz stat_reset_timestamp;
} PgStat_GlobalStats;
+/*
+ * WAL statistics kept in the stats collector
+ */
+typedef struct PgStat_WalStats
+{
+ PgStat_Counter wal_buffers_full;
+ TimestampTz stat_reset_timestamp;
+} PgStat_WalStats;
+
/*
* SLRU statistics kept in the stats collector
*/
@@ -1265,6 +1287,11 @@ extern char *pgstat_stat_filename;
*/
extern PgStat_MsgBgWriter BgWriterStats;
+/*
+ * WAL writes statistics counter is updated by backends and background processes
+ */
+extern PgStat_MsgWal WalStats;
+
/*
* Updated by pgstat_count_buffer_*_time macros
*/
@@ -1464,6 +1491,7 @@ extern void pgstat_twophase_postabort(TransactionId xid, uint16 info,
extern void pgstat_send_archiver(const char *xlog, bool failed);
extern void pgstat_send_bgwriter(void);
+extern void pgstat_send_wal(void);
/* ----------
* Support functions for the SQL-callable functions to
@@ -1478,6 +1506,7 @@ extern PgStat_StatFuncEntry *pgstat_fetch_stat_funcentry(Oid funcid);
extern int pgstat_fetch_stat_numbackends(void);
extern PgStat_ArchiverStats *pgstat_fetch_stat_archiver(void);
extern PgStat_GlobalStats *pgstat_fetch_global(void);
+extern PgStat_WalStats *pgstat_fetch_stat_wal(void);
extern PgStat_SLRUStats *pgstat_fetch_slru(void);
extern void pgstat_count_slru_page_zeroed(int slru_idx);
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2a18dc423e..1e4ac4432e 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2129,6 +2129,8 @@ pg_stat_user_tables| SELECT pg_stat_all_tables.relid,
pg_stat_all_tables.autoanalyze_count
FROM pg_stat_all_tables
WHERE ((pg_stat_all_tables.schemaname <> ALL (ARRAY['pg_catalog'::name, 'information_schema'::name])) AND (pg_stat_all_tables.schemaname !~ '^pg_toast'::text));
+pg_stat_wal| SELECT pg_stat_get_wal_buffers_full() AS wal_buffers_full,
+ pg_stat_get_wal_stat_reset_time() AS stats_reset;
pg_stat_wal_receiver| SELECT s.pid,
s.status,
s.receive_start_lsn,
diff --git a/src/test/regress/expected/sysviews.out b/src/test/regress/expected/sysviews.out
index 1cffc3349d..81bdacf59d 100644
--- a/src/test/regress/expected/sysviews.out
+++ b/src/test/regress/expected/sysviews.out
@@ -76,6 +76,13 @@ select count(*) >= 0 as ok from pg_prepared_xacts;
t
(1 row)
+-- There must be only one record
+select count(*) = 1 as ok from pg_stat_wal;
+ ok
+----
+ t
+(1 row)
+
-- This is to record the prevailing planner enable_foo settings during
-- a regression test run.
select name, setting from pg_settings where name like 'enable%';
diff --git a/src/test/regress/sql/sysviews.sql b/src/test/regress/sql/sysviews.sql
index ac4a0e1cbb..b9b875bc6a 100644
--- a/src/test/regress/sql/sysviews.sql
+++ b/src/test/regress/sql/sysviews.sql
@@ -37,6 +37,9 @@ select count(*) = 0 as ok from pg_prepared_statements;
-- See also prepared_xacts.sql
select count(*) >= 0 as ok from pg_prepared_xacts;
+-- There must be only one record
+select count(*) = 1 as ok from pg_stat_wal;
+
-- This is to record the prevailing planner enable_foo settings during
-- a regression test run.
select name, setting from pg_settings where name like 'enable%';
