skip vacuuming the table if last time vacuum percent less than 10

Author: zhjwpku

src/backend/postmaster/autovacuum.c

@@ -3093,6 +3093,22 @@ relation_needs_vacanalyze(Oid relid,
 		float4		reltuples = classForm->reltuples;
 		int32		relpages = classForm->relpages;
 		int32		relallfrozen = classForm->relallfrozen;
+		float4		last_remove_tuples_percent = tabentry->last_autovacuum_removed_tuples_percent;
+		TimestampTz last_autovacuum_time = tabentry->last_autovacuum_time;
+
+		/*
+		 * If the last autovacuum removed tuples is less than 10% of the
+		 * current dead tuples, then skip vacuuming this table for some time.
+		 */
+		if (!TimestampDifferenceExceedsSeconds(last_autovacuum_time,
+											   GetCurrentTimestamp(),
+											   autovacuum_naptime) &&
+			last_remove_tuples_percent < 10.0)
+		{
+			*doanalyze = false;
+			*dovacuum = false;
+			return;
+		}
 
 		vactuples = tabentry->dead_tuples;
 		instuples = tabentry->ins_since_vacuum;

src/backend/utils/activity/pgstat_relation.c

@@ -217,6 +217,7 @@ pgstat_report_vacuum(Oid tableoid, bool shared,
 	Oid			dboid = (shared ? InvalidOid : MyDatabaseId);
 	TimestampTz ts;
 	PgStat_Counter elapsedtime;
+	PgStat_Counter old_dead_tuples;
 
 	if (!pgstat_track_counts)
 		return;
@@ -232,6 +233,7 @@ pgstat_report_vacuum(Oid tableoid, bool shared,
 	shtabentry = (PgStatShared_Relation *) entry_ref->shared_stats;
 	tabentry = &shtabentry->stats;
 
+	old_dead_tuples = tabentry->dead_tuples;
 	tabentry->live_tuples = livetuples;
 	tabentry->dead_tuples = deadtuples;
 
@@ -250,6 +252,11 @@ pgstat_report_vacuum(Oid tableoid, bool shared,
 	if (AmAutoVacuumWorkerProcess())
 	{
 		tabentry->last_autovacuum_time = ts;
+		if (old_dead_tuples > deadtuples)
+			tabentry->last_autovacuum_removed_tuples_percent =
+				100 * (old_dead_tuples - deadtuples) / old_dead_tuples;
+		else
+			tabentry->last_autovacuum_removed_tuples_percent = 0;
 		tabentry->autovacuum_count++;
 		tabentry->total_autovacuum_time += elapsedtime;
 	}

src/include/pgstat.h

@@ -443,6 +443,7 @@ typedef struct PgStat_StatTabEntry
 	TimestampTz last_vacuum_time;	/* user initiated vacuum */
 	PgStat_Counter vacuum_count;
 	TimestampTz last_autovacuum_time;	/* autovacuum initiated */
+	PgStat_Counter last_autovacuum_removed_tuples_percent;
 	PgStat_Counter autovacuum_count;
 	TimestampTz last_analyze_time;	/* user initiated */
 	PgStat_Counter analyze_count;