On 2020-09-11 01:40, Fujii Masao wrote:
On 2020/09/09 13:57, Masahiro Ikeda wrote:
On 2020-09-07 16:19, Fujii Masao wrote:
On 2020/09/07 9:58, Masahiro Ikeda wrote:
Thanks for the review and advice!
On 2020-09-03 16:05, Fujii Masao wrote:
On 2020/09/02 18:56, Masahiro Ikeda wrote:
+/* ----------
+ * Backend types
+ * ----------
You seem to forget to add "*/" into the above comment.
This issue could cause the following compiler warning.
../../src/include/pgstat.h:761:1: warning: '/*' within block
comment [-Wcomment]
Thanks for the comment. I fixed.
Thanks for the fix! But why are those comments necessary?
Sorry about that. This comment is not necessary.
I removed it.
The pg_stat_walwriter is not security restricted now, so ordinary
users can access it.
It has the same security level as pg_stat_archiver. If you have
any comments, please let me know.
+ <structfield>dirty_writes</structfield> <type>bigint</type>
I guess that the column name "dirty_writes" derived from
the DTrace probe name. Isn't this name confusing? We should
rename it to "wal_buffers_full" or something?
I agree and rename it to "wal_buffers_full".
+/* ----------
+ * PgStat_MsgWalWriter Sent by the walwriter to update
statistics.
This comment seems not accurate because backends also send it.
+/*
+ * WAL writes statistics counter is updated in XLogWrite function
+ */
+extern PgStat_MsgWalWriter WalWriterStats;
This comment seems not right because the counter is not updated in
XLogWrite().
Right. I fixed it to "Sent by each backend and background workers to
update WAL statistics."
In the future, other statistics will be included so I remove the
function's name.
+-- There will surely and maximum one record
+select count(*) = 1 as ok from pg_stat_walwriter;
What about changing this comment to "There must be only one
record"?
Thanks, I fixed.
+ WalWriterStats.m_xlog_dirty_writes++;
LWLockRelease(WALWriteLock);
Since WalWriterStats.m_xlog_dirty_writes doesn't need to be
protected
with WALWriteLock, isn't it better to increment that after
releasing the lock?
Thanks, I fixed.
+CREATE VIEW pg_stat_walwriter AS
+ SELECT
+ pg_stat_get_xlog_dirty_writes() AS dirty_writes,
+ pg_stat_get_walwriter_stat_reset_time() AS stats_reset;
+
CREATE VIEW pg_stat_progress_vacuum AS
In system_views.sql, the definition of pg_stat_walwriter should be
placed just after that of pg_stat_bgwriter not
pg_stat_progress_analyze.
OK, I fixed it.
}
-
/*
* We found an existing collector stats file. Read it and put
all the
You seem to accidentally have removed the empty line here.
Sorry about that. I fixed it.
- errhint("Target must be \"archiver\" or
\"bgwriter\".")));
+ errhint("Target must be \"archiver\" or
\"bgwriter\" or
\"walwriter\".")));
There are two "or" in the message, but the former should be
replaced with ","?
Thanks, I fixed.
On 2020-09-05 18:40, Magnus Hagander wrote:
On Fri, Sep 4, 2020 at 5:42 AM Fujii Masao
<masao.fu...@oss.nttdata.com> wrote:
On 2020/09/04 11:50, tsunakawa.ta...@fujitsu.com wrote:
From: Fujii Masao <masao.fu...@oss.nttdata.com>
I changed the view name from pg_stat_walwrites to
pg_stat_walwriter.
I think it is better to match naming scheme with other views
like
pg_stat_bgwriter,
which is for bgwriter statistics but it has the statistics
related to backend.
I prefer the view name pg_stat_walwriter for the consistency
with
other view names. But we also have pg_stat_wal_receiver. Which
makes me think that maybe pg_stat_wal_writer is better for
the consistency. Thought? IMO either of them works for me.
I'd like to hear more opinons about this.
I think pg_stat_bgwriter is now a misnomer, because it contains
the backends' activity. Likewise, pg_stat_walwriter leads to
misunderstanding because its information is not limited to WAL
writer.
How about simply pg_stat_wal? In the future, we may want to
include WAL reads in this view, e.g. reading undo logs in zheap.
Sounds reasonable.
+1.
pg_stat_bgwriter has had the "wrong name" for quite some time now
--
it became even more apparent when the checkpointer was split out to
it's own process, and that's not exactly a recent change. And it
had
allocs in it from day one...
I think naming it for what the data in it is ("wal") rather than
which
process deals with it ("walwriter") is correct, unless the
statistics
can be known to only *ever* affect one type of process. (And then
different processes can affect different columns in the view). As a
general rule -- and that's from what I can tell exactly what's
being
proposed.
Thanks for your comments. I agree with your opinions.
I changed the view name to "pg_stat_wal".
I fixed the code to send the WAL statistics from not only backend
and walwriter
but also checkpointer, walsender and autovacuum worker.
Good point! Thanks for updating the patch!
@@ -604,6 +604,7 @@ heap_vacuum_rel(Relation onerel, VacuumParams
*params,
onerel->rd_rel->relisshared,
Max(new_live_tuples, 0),
vacrelstats->new_dead_tuples);
+ pgstat_send_wal();
I guess that you changed heap_vacuum_rel() as above so that
autovacuum
workers can send WAL stats. But heap_vacuum_rel() can be called by
the processes (e.g., backends) other than autovacuum workers? Also
what happens if autovacuum workers just do ANALYZE only? In that
case,
heap_vacuum_rel() may not be called.
Currently autovacuum worker reports the stats at the exit via
pgstat_beshutdown_hook(). Unlike other processes, autovacuum worker
is not the process that basically keeps running during the service.
It exits
after it does vacuum or analyze. So ISTM that it's not bad to report
the stats
only at the exit, in autovacuum worker case. There is no need to add
extra
code for WAL stats report by autovacuum worker. Thought?
Thanks, I understood. I removed this code.
@@ -1430,6 +1430,9 @@ WalSndWaitForWal(XLogRecPtr loc)
else
RecentFlushPtr = GetXLogReplayRecPtr(NULL);
+ /* Send wal statistics */
+ pgstat_send_wal();
AFAIR logical walsender uses three loops in WalSndLoop(),
WalSndWriteData()
and WalSndWaitForWal(). But could you tell me why added
pgstat_send_wal()
into WalSndWaitForWal()? I'd like to know why WalSndWaitForWal() is
the best
for that purpose.
I checked what function calls XLogBackgroundFlush() which calls
AdvanceXLInsertBuffer() to increment m_wal_buffers_full.
I found that WalSndWaitForWal() calls it, so I added it.
Ok. But XLogBackgroundFlush() calls AdvanceXLInsertBuffer() wit the
second argument opportunistic=true, so in this case WAL write by
wal_buffers full seems to never happen. Right? If this understanding
is right, WalSndWaitForWal() doesn't need to call pgstat_send_wal().
Probably also walwriter doesn't need to do that.
The logical rep walsender can generate WAL and call
AdvanceXLInsertBuffer() when it executes the replication commands like
CREATE_REPLICATION_SLOT. But this case is already covered by
pgstat_report_activity()->pgstat_send_wal() called in PostgresMain(),
with your patch. So no more calls to pgstat_send_wal() seems necessary
for logical rep walsender.
Thanks for your reviews. I didn't notice that.
I updated the patches.
On 2020-09-11 17:13, Fujii Masao wrote:
On 2020/09/11 16:54, Kyotaro Horiguchi wrote:
At Fri, 11 Sep 2020 13:48:49 +0900, Fujii Masao
<masao.fu...@oss.nttdata.com> wrote in
On 2020/09/11 12:17, Kyotaro Horiguchi wrote:
Hello.
At Wed, 09 Sep 2020 13:57:37 +0900, Masahiro Ikeda
<ikeda...@oss.nttdata.com> wrote in
I checked what function calls XLogBackgroundFlush() which calls
AdvanceXLInsertBuffer() to increment m_wal_buffers_full.
I found that WalSndWaitForWal() calls it, so I added it.
Is it better to move it in WalSndLoop() like the attached patch?
By the way, we are counting some wal-related numbers in
pgWalUsage.(bytes, records, fpi). Since now that we are going to
have
a new view related to WAL statistics, wouln't it be more useful to
show them together in the view?
Probably yes. But IMO it's better to commit the current patch first,
and then add those stats into the view after confirming exposing them
is useful.
I'm fine with that.
BTW, to expose the total WAL bytes, I think it's better to just save
the LSN at when pg_stat_wal is reset rather than counting
pgWalUsage.bytes. If we do that, we can easily total WAL bytes by
subtracting that LSN from the latest LSN. Also saving the LSN at the
reset timing causes obviously less overhead than counting
pgWalUsage.bytes.
pgWalUsage is always counting so it doesn't add any overhead.
Yes. And I'm a bit concerned about the overhead by frequent message
sent for WAL bytes to the stats collector.
Thanks for the comments.
I agree that we need to add more wal-related statistics
after this patch is committed.
Regards,
--
Masahiro Ikeda
NTT DATA CORPORATION
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 673a0e73e4..6d56912221 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -424,6 +424,13 @@ 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 the WAL writing activity. See
+ <xref linkend="monitoring-pg-stat-wal-view"/> 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 +3287,56 @@ 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 the WAL writing 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 WAL writes when the <xref linkend="guc-wal-buffers"/> are 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 +4725,9 @@ 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 a38371a64f..2047a68a86 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2194,6 +2194,7 @@ 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/bgwriter.c b/src/backend/postmaster/bgwriter.c
index c96568149f..d13fe63615 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -252,6 +252,9 @@ BackgroundWriterMain(void)
*/
pgstat_send_bgwriter();
+ /* Send wal statistics */
+ pgstat_send_wal();
+
if (FirstCallSinceLastCheckpoint())
{
/*
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index 45f5deca72..25817b0789 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -508,6 +508,9 @@ 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..7127beca66 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -141,6 +141,13 @@ char *pgstat_stat_tmpname = NULL;
*/
PgStat_MsgBgWriter BgWriterStats;
+/*
+ * 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;
+
/*
* List of SLRU names that we keep stats for. There is no central registry of
* SLRUs, so we use this fixed list instead. The "other" entry is used for
@@ -281,6 +288,7 @@ 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 +361,7 @@ 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 +947,9 @@ 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 +1382,13 @@ 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 +2688,21 @@ 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 +4448,38 @@ 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 +4719,10 @@ 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 +4992,12 @@ 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 +5257,12 @@ 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 and wal 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 +5271,7 @@ 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 +5341,17 @@ 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
*/
@@ -5633,6 +5717,17 @@ pgstat_read_db_statsfile_timestamp(Oid databaseid, bool permanent,
return false;
}
+ /*
+ * Read wal stats struct
+ */
+ if (fread(&walStats, 1, sizeof(walStats), fpin) != sizeof(walStats))
+ {
+ ereport(pgStatRunningInCollector ? LOG : WARNING,
+ (errmsg("corrupted statistics file \"%s\"", statfile)));
+ FreeFile(fpin);
+ return false;
+ }
+
/*
* Read SLRU stats struct
*/
@@ -6213,6 +6308,12 @@ 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 +6528,18 @@ 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/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index 358c0916ac..617fc7915a 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -257,6 +257,9 @@ WalWriterMain(void)
else if (left_till_hibernate > 0)
left_till_hibernate--;
+ /* Send wal statistics */
+ pgstat_send_wal();
+
/*
* Sleep until we are signaled or WalWriterDelay has elapsed. If we
* haven't done anything useful for quite some time, lengthen the
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 687509ba92..22f70cc097 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5484,6 +5484,14 @@
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 WAL writes when the wal buffers are 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 the walwriter',
+ 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..eb706068ba 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 each backend and background workers to update WAL statistics.
+ * ----------
+ */
+typedef struct PgStat_MsgWal
+{
+ PgStat_MsgHdr m_hdr;
+ PgStat_Counter m_wal_buffers_full; /* number of WAL write caused by full of WAL buffers */
+} 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;
@@ -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; /* number of WAL write caused by full of WAL buffers */
+ TimestampTz stat_reset_timestamp; /* last time when the stats reset */
+} 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 backend and background workers
+ */
+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%';
