Add an EXPLAIN (BUFFERS) option to show buffer-usage statistics.

This patch also removes buffer-usage statistics from the track_counts
output, since this (or the global server statistics) is deemed to be a better
interface to this information.

Itagaki Takahiro, reviewed by Euler Taveira de Oliveira.

src/backend/executor/execMain.c

@@ -26,7 +26,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.337 2009/12/11 18:14:43 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.338 2009/12/15 04:57:47 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -180,7 +180,7 @@ standard_ExecutorStart(QueryDesc *queryDesc, int eflags)
 	 */
 	estate->es_snapshot = RegisterSnapshot(queryDesc->snapshot);
 	estate->es_crosscheck_snapshot = RegisterSnapshot(queryDesc->crosscheck_snapshot);
-	estate->es_instrument = queryDesc->doInstrument;
+	estate->es_instrument = queryDesc->instrument_options;
 
 	/*
 	 * Initialize the plan state tree
@@ -859,7 +859,7 @@ InitResultRelInfo(ResultRelInfo *resultRelInfo,
 				  Relation resultRelationDesc,
 				  Index resultRelationIndex,
 				  CmdType operation,
-				  bool doInstrument)
+				  int instrument_options)
 {
 	/*
 	 * Check valid relkind ... parser and/or planner should have noticed this
@@ -914,10 +914,8 @@ InitResultRelInfo(ResultRelInfo *resultRelInfo,
 			palloc0(n * sizeof(FmgrInfo));
 		resultRelInfo->ri_TrigWhenExprs = (List **)
 			palloc0(n * sizeof(List *));
-		if (doInstrument)
-			resultRelInfo->ri_TrigInstrument = InstrAlloc(n);
-		else
-			resultRelInfo->ri_TrigInstrument = NULL;
+		if (instrument_options)
+			resultRelInfo->ri_TrigInstrument = InstrAlloc(n, instrument_options);
 	}
 	else
 	{

src/backend/executor/execProcnode.c

@@ -12,7 +12,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execProcnode.c,v 1.68 2009/10/12 18:10:41 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execProcnode.c,v 1.69 2009/12/15 04:57:47 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -321,7 +321,7 @@ ExecInitNode(Plan *node, EState *estate, int eflags)
 
 	/* Set up instrumentation for this node if requested */
 	if (estate->es_instrument)
-		result->instrument = InstrAlloc(1);
+		result->instrument = InstrAlloc(1, estate->es_instrument);
 
 	return result;
 }

src/backend/executor/functions.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.137 2009/12/14 02:15:51 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.138 2009/12/15 04:57:47 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -414,7 +414,7 @@ postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
 								 fcache->src,
 								 snapshot, InvalidSnapshot,
 								 dest,
-								 fcache->paramLI, false);
+								 fcache->paramLI, 0);
 	else
 		es->qd = CreateUtilityQueryDesc(es->stmt,
 										fcache->src,

src/backend/executor/instrument.c

@@ -7,7 +7,7 @@
  * Copyright (c) 2001-2009, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/instrument.c,v 1.22 2009/01/01 17:23:41 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/instrument.c,v 1.23 2009/12/15 04:57:47 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,14 +17,28 @@
 
 #include "executor/instrument.h"
 
+BufferUsage			pgBufferUsage;
+
+static void BufferUsageAccumDiff(BufferUsage *dst,
+		const BufferUsage *add, const BufferUsage *sub);
 
 /* Allocate new instrumentation structure(s) */
 Instrumentation *
-InstrAlloc(int n)
+InstrAlloc(int n, int instrument_options)
 {
-	Instrumentation *instr = palloc0(n * sizeof(Instrumentation));
+	Instrumentation *instr;
 
-	/* we don't need to do any initialization except zero 'em */
+	/* timer is always required for now */
+	Assert(instrument_options & INSTRUMENT_TIMER);
+
+	instr = palloc0(n * sizeof(Instrumentation));
+	if (instrument_options & INSTRUMENT_BUFFERS)
+	{
+		int		i;
+
+		for (i = 0; i < n; i++)
+			instr[i].needs_bufusage = true;
+	}
 
 	return instr;
 }
@@ -37,6 +51,10 @@ InstrStartNode(Instrumentation *instr)
 		INSTR_TIME_SET_CURRENT(instr->starttime);
 	else
 		elog(DEBUG2, "InstrStartNode called twice in a row");
+
+	/* initialize buffer usage per plan node */
+	if (instr->needs_bufusage)
+		instr->bufusage_start = pgBufferUsage;
 }
 
 /* Exit from a plan node */
@@ -59,6 +77,11 @@ InstrStopNode(Instrumentation *instr, double nTuples)
 
 	INSTR_TIME_SET_ZERO(instr->starttime);
 
+	/* Adds delta of buffer usage to node's count. */
+	if (instr->needs_bufusage)
+		BufferUsageAccumDiff(&instr->bufusage,
+			&pgBufferUsage, &instr->bufusage_start);
+
 	/* Is this the first tuple of this cycle? */
 	if (!instr->running)
 	{
@@ -95,3 +118,19 @@ InstrEndLoop(Instrumentation *instr)
 	instr->firsttuple = 0;
 	instr->tuplecount = 0;
 }
+
+static void
+BufferUsageAccumDiff(BufferUsage *dst,
+					 const BufferUsage *add,
+					 const BufferUsage *sub)
+{
+	/* dst += add - sub */
+	dst->shared_blks_hit += add->shared_blks_hit - sub->shared_blks_hit;
+	dst->shared_blks_read += add->shared_blks_read - sub->shared_blks_read;
+	dst->shared_blks_written += add->shared_blks_written - sub->shared_blks_written;
+	dst->local_blks_hit += add->local_blks_hit - sub->local_blks_hit;
+	dst->local_blks_read += add->local_blks_read - sub->local_blks_read;
+	dst->local_blks_written += add->local_blks_written - sub->local_blks_written;
+	dst->temp_blks_read += add->temp_blks_read - sub->temp_blks_read;
+	dst->temp_blks_written += add->temp_blks_written - sub->temp_blks_written;
+}

src/backend/executor/spi.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.211 2009/11/04 22:26:06 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.212 2009/12/15 04:57:47 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1908,7 +1908,7 @@ _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
 										plansource->query_string,
 										snap, crosscheck_snapshot,
 										dest,
-										paramLI, false);
+										paramLI, 0);
 				res = _SPI_pquery(qdesc, fire_triggers,
 								  canSetTag ? tcount : 0);
 				FreeQueryDesc(qdesc);