EXPLAIN ANALYZE feature to measure and show actual runtimes and tuple

counts alongside the planner's estimates.  By Martijn van Oosterhout,
with some further work by Tom Lane.

src/backend/executor/instrument.c

@@ -0,0 +1,122 @@
+/*-------------------------------------------------------------------------
+ *
+ * instrument.c
+ *	 functions for instrumentation of plan execution 
+ *
+ *
+ * Copyright (c) 2001, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/instrument.c,v 1.1 2001/09/18 01:59:06 tgl Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <unistd.h>
+
+#include "executor/instrument.h"
+
+
+/* Allocate new instrumentation structure */
+Instrumentation *
+InstrAlloc(void)
+{
+	Instrumentation *instr = palloc( sizeof(Instrumentation) );
+
+	memset( instr, 0, sizeof(Instrumentation) );
+
+	return instr;
+}
+
+/* Entry to a plan node */
+void
+InstrStartNode(Instrumentation *instr)
+{
+	if (!instr)
+		return;
+
+	if (instr->starttime.tv_sec != 0 || instr->starttime.tv_usec != 0)
+		elog(DEBUG, "InstrStartTimer called twice in a row");
+	else
+		gettimeofday(&instr->starttime, NULL);
+}
+
+/* Exit from a plan node */
+void
+InstrStopNode(Instrumentation *instr, bool returnedTuple)
+{
+	struct timeval endtime;
+  
+	if (!instr)
+		return;
+
+	if (instr->starttime.tv_sec == 0 && instr->starttime.tv_usec == 0)
+	{
+		elog(DEBUG, "InstrStopNode without start");
+		return;
+	}
+  
+	gettimeofday(&endtime, NULL);
+  
+	instr->counter.tv_sec  += endtime.tv_sec  - instr->starttime.tv_sec;
+	instr->counter.tv_usec += endtime.tv_usec - instr->starttime.tv_usec;
+
+	/* Normalize after each add to avoid overflow/underflow of tv_usec */
+	while (instr->counter.tv_usec < 0)
+	{
+		instr->counter.tv_usec += 1000000;
+		instr->counter.tv_sec--;
+	}
+	while (instr->counter.tv_usec >= 1000000)
+	{
+		instr->counter.tv_usec -= 1000000;
+		instr->counter.tv_sec++;
+	}
+
+	instr->starttime.tv_sec = 0;
+	instr->starttime.tv_usec = 0;
+
+	/* Is this the first tuple of this cycle? */
+	if (!instr->running)
+	{
+		instr->running = true;
+		instr->firsttuple = (double) instr->counter.tv_sec +
+			(double) instr->counter.tv_usec / 1000000.0;
+	}
+
+	if (returnedTuple)
+		instr->tuplecount += 1;
+}
+
+/* Finish a run cycle for a plan node */
+void 
+InstrEndLoop(Instrumentation *instr)
+{
+	double totaltime;
+
+	if (!instr)
+		return;
+
+	/* Skip if nothing has happened, or already shut down */
+	if (!instr->running)
+		return;
+
+	/* Accumulate statistics */
+	totaltime = (double) instr->counter.tv_sec +
+		(double) instr->counter.tv_usec / 1000000.0; 
+
+	instr->startup += instr->firsttuple;
+	instr->total   += totaltime;
+	instr->ntuples += instr->tuplecount;
+	instr->nloops += 1;
+
+	/* Reset for next cycle (if any) */
+	instr->running = false;
+	instr->starttime.tv_sec = 0;
+	instr->starttime.tv_usec = 0;
+	instr->counter.tv_sec = 0;
+	instr->counter.tv_usec = 0;
+	instr->firsttuple = 0;
+	instr->tuplecount = 0;
+}