Improve logging of auto-vacuum and auto-analyze

When logging auto-vacuum and auto-analyze activity, include the I/O
timing if track_io_timing is enabled.  Also, for auto-analyze, add the
read rate and the dirty rate, similar to how that information has
historically been logged for auto-vacuum.

Stephen Frost and Jakub Wartak

Reviewed-By: Heikki Linnakangas, Tomas Vondra
Discussion: https://www.postgresql.org/message-id/VI1PR0701MB69603A433348EDCF783C6ECBF6EF0%40VI1PR0701MB6960.eurprd07.prod.outlook.com

Author: sfrost

doc/src/sgml/config.sgml

@@ -7457,9 +7457,11 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         I/O timing information is
         displayed in <link linkend="monitoring-pg-stat-database-view">
         <structname>pg_stat_database</structname></link>, in the output of
-        <xref linkend="sql-explain"/> when the <literal>BUFFERS</literal> option is
-        used, and by <xref linkend="pgstatstatements"/>.  Only superusers can
-        change this setting.
+        <xref linkend="sql-explain"/> when the <literal>BUFFERS</literal> option
+        is used, by autovacuum for auto-vacuums and auto-analyzes, when
+        <xref linkend="guc-log-autovacuum-min-duration"/> is set and by
+        <xref linkend="pgstatstatements"/>.  Only superusers can change this
+        setting.
        </para>
       </listitem>
      </varlistentry>

src/backend/access/heap/vacuumlazy.c

@@ -441,6 +441,8 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 	TransactionId new_frozen_xid;
 	MultiXactId new_min_multi;
 	ErrorContextCallback errcallback;
+	PgStat_Counter startreadtime = 0;
+	PgStat_Counter startwritetime = 0;
 
 	Assert(params != NULL);
 	Assert(params->index_cleanup != VACOPT_TERNARY_DEFAULT);
@@ -455,6 +457,11 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 	{
 		pg_rusage_init(&ru0);
 		starttime = GetCurrentTimestamp();
+		if (track_io_timing)
+		{
+			startreadtime = pgStatBlockReadTime;
+			startwritetime = pgStatBlockWriteTime;
+		}
 	}
 
 	if (params->options & VACOPT_VERBOSE)
@@ -675,6 +682,17 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 							 (long long) VacuumPageDirty);
 			appendStringInfo(&buf, _("avg read rate: %.3f MB/s, avg write rate: %.3f MB/s\n"),
 							 read_rate, write_rate);
+			if (track_io_timing)
+			{
+				appendStringInfoString(&buf, _("I/O Timings:"));
+				if (pgStatBlockReadTime - startreadtime > 0)
+					appendStringInfo(&buf, _(" read=%.3f"),
+									 (double) (pgStatBlockReadTime - startreadtime) / 1000);
+				if (pgStatBlockWriteTime - startwritetime > 0)
+					appendStringInfo(&buf, _(" write=%.3f"),
+									 (double) (pgStatBlockWriteTime - startwritetime) / 1000);
+				appendStringInfoChar(&buf, '\n');
+			}
 			appendStringInfo(&buf, _("system usage: %s\n"), pg_rusage_show(&ru0));
 			appendStringInfo(&buf,
 							 _("WAL usage: %ld records, %ld full page images, %llu bytes"),

src/backend/commands/analyze.c

@@ -312,6 +312,11 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 	Oid			save_userid;
 	int			save_sec_context;
 	int			save_nestlevel;
+	int64		AnalyzePageHit = VacuumPageHit;
+	int64		AnalyzePageMiss = VacuumPageMiss;
+	int64		AnalyzePageDirty = VacuumPageDirty;
+	PgStat_Counter startreadtime = 0;
+	PgStat_Counter startwritetime = 0;
 
 	if (inh)
 		ereport(elevel,
@@ -346,8 +351,14 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 	/* measure elapsed time iff autovacuum logging requires it */
 	if (IsAutoVacuumWorkerProcess() && params->log_min_duration >= 0)
 	{
+		if (track_io_timing)
+		{
+			startreadtime = pgStatBlockReadTime;
+			startwritetime = pgStatBlockWriteTime;
+		}
+
 		pg_rusage_init(&ru0);
-		if (params->log_min_duration > 0)
+		if (params->log_min_duration >= 0)
 			starttime = GetCurrentTimestamp();
 	}
 
@@ -692,15 +703,90 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 	/* Log the action if appropriate */
 	if (IsAutoVacuumWorkerProcess() && params->log_min_duration >= 0)
 	{
+		TimestampTz endtime = GetCurrentTimestamp();
+
 		if (params->log_min_duration == 0 ||
-			TimestampDifferenceExceeds(starttime, GetCurrentTimestamp(),
+			TimestampDifferenceExceeds(starttime, endtime,
 									   params->log_min_duration))
+		{
+			long		delay_in_ms;
+			double		read_rate = 0;
+			double		write_rate = 0;
+			StringInfoData buf;
+
+			/*
+			 * Calculate the difference in the Page Hit/Miss/Dirty that
+			 * happened as part of the analyze by subtracting out the
+			 * pre-analyze values which we saved above.
+			 */
+			AnalyzePageHit = VacuumPageHit - AnalyzePageHit;
+			AnalyzePageMiss = VacuumPageMiss - AnalyzePageMiss;
+			AnalyzePageDirty = VacuumPageDirty - AnalyzePageDirty;
+
+			/*
+			 * We do not expect an analyze to take > 25 days and it simplifies
+			 * things a bit to use TimestampDifferenceMilliseconds.
+			 */
+			delay_in_ms = TimestampDifferenceMilliseconds(starttime, endtime);
+
+			/*
+			 * Note that we are reporting these read/write rates in the same
+			 * manner as VACUUM does, which means that while the 'average read
+			 * rate' here actually corresponds to page misses and resulting
+			 * reads which are also picked up by track_io_timing, if enabled,
+			 * the 'average write rate' is actually talking about the rate of
+			 * pages being dirtied, not being written out, so it's typical to
+			 * have a non-zero 'avg write rate' while I/O Timings only reports
+			 * reads.
+			 *
+			 * It's not clear that an ANALYZE will ever result in
+			 * FlushBuffer() being called, but we track and support reporting
+			 * on I/O write time in case that changes as it's practically free
+			 * to do so anyway.
+			 */
+
+			if (delay_in_ms > 0)
+			{
+				read_rate = (double) BLCKSZ * AnalyzePageMiss / (1024 * 1024) /
+					(delay_in_ms / 1000.0);
+				write_rate = (double) BLCKSZ * AnalyzePageDirty / (1024 * 1024) /
+					(delay_in_ms / 1000.0);
+			}
+
+			/*
+			 * We split this up so we don't emit empty I/O timing values when
+			 * track_io_timing isn't enabled.
+			 */
+
+			initStringInfo(&buf);
+			appendStringInfo(&buf, _("automatic analyze of table \"%s.%s.%s\"\n"),
+							 get_database_name(MyDatabaseId),
+							 get_namespace_name(RelationGetNamespace(onerel)),
+							 RelationGetRelationName(onerel));
+			appendStringInfo(&buf, _("buffer usage: %lld hits, %lld misses, %lld dirtied\n"),
+							 (long long) AnalyzePageHit,
+							 (long long) AnalyzePageMiss,
+							 (long long) AnalyzePageDirty);
+			appendStringInfo(&buf, _("avg read rate: %.3f MB/s, avg write rate: %.3f MB/s\n"),
+							 read_rate, write_rate);
+			if (track_io_timing)
+			{
+				appendStringInfoString(&buf, _("I/O Timings:"));
+				if (pgStatBlockReadTime - startreadtime > 0)
+					appendStringInfo(&buf, _(" read=%.3f"),
+									 (double) (pgStatBlockReadTime - startreadtime) / 1000);
+				if (pgStatBlockWriteTime - startwritetime > 0)
+					appendStringInfo(&buf, _(" write=%.3f"),
+									 (double) (pgStatBlockWriteTime - startwritetime) / 1000);
+				appendStringInfoChar(&buf, '\n');
+			}
+			appendStringInfo(&buf, _("system usage: %s"), pg_rusage_show(&ru0));
+
 			ereport(LOG,
-					(errmsg("automatic analyze of table \"%s.%s.%s\" system usage: %s",
-							get_database_name(MyDatabaseId),
-							get_namespace_name(RelationGetNamespace(onerel)),
-							RelationGetRelationName(onerel),
-							pg_rusage_show(&ru0))));
+					(errmsg_internal("%s", buf.data)));
+
+			pfree(buf.data);
+		}
 	}
 
 	/* Roll back any GUC changes executed by index functions */