diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 7a290e8836..02c9534cab 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994-5, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.129 2004/12/31 21:59:41 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.130 2005/03/20 22:27:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -46,7 +46,7 @@ typedef struct ExplainState
 
 static void ExplainOneQuery(Query *query, ExplainStmt *stmt,
 				TupOutputState *tstate);
-static double elapsed_time(struct timeval * starttime);
+static double elapsed_time(instr_time * starttime);
 static void explain_outNode(StringInfo str,
 				Plan *plan, PlanState *planstate,
 				Plan *outer_plan,
@@ -212,12 +212,12 @@ void
 ExplainOnePlan(QueryDesc *queryDesc, ExplainStmt *stmt,
 			   TupOutputState *tstate)
 {
-	struct timeval starttime;
+	instr_time  starttime;
 	double		totaltime = 0;
 	ExplainState *es;
 	StringInfo	str;
 
-	gettimeofday(&starttime, NULL);
+	INSTR_TIME_SET_CURRENT(starttime);
 
 	/* If analyzing, we need to cope with queued triggers */
 	if (stmt->analyze)
@@ -275,7 +275,7 @@ ExplainOnePlan(QueryDesc *queryDesc, ExplainStmt *stmt,
 	 * Close down the query and free resources; also run any queued
 	 * AFTER triggers.  Include time for this in the total runtime.
 	 */
-	gettimeofday(&starttime, NULL);
+	INSTR_TIME_SET_CURRENT(starttime);
 
 	ExecutorEnd(queryDesc);
 
@@ -303,14 +303,15 @@ ExplainOnePlan(QueryDesc *queryDesc, ExplainStmt *stmt,
 	pfree(es);
 }
 
-/* Compute elapsed time in seconds since given gettimeofday() timestamp */
+/* Compute elapsed time in seconds since given timestamp */
 static double
-elapsed_time(struct timeval * starttime)
+elapsed_time(instr_time * starttime)
 {
-	struct timeval endtime;
+	instr_time endtime;
 
-	gettimeofday(&endtime, NULL);
+	INSTR_TIME_SET_CURRENT(endtime);
 
+#ifndef WIN32
 	endtime.tv_sec -= starttime->tv_sec;
 	endtime.tv_usec -= starttime->tv_usec;
 	while (endtime.tv_usec < 0)
@@ -318,8 +319,11 @@ elapsed_time(struct timeval * starttime)
 		endtime.tv_usec += 1000000;
 		endtime.tv_sec--;
 	}
-	return (double) endtime.tv_sec +
-		(double) endtime.tv_usec / 1000000.0;
+#else  /* WIN32 */
+	endtime.QuadPart -= starttime->QuadPart;
+#endif
+
+	return INSTR_TIME_GET_DOUBLE(endtime);
 }
 
 /*
diff --git a/src/backend/executor/instrument.c b/src/backend/executor/instrument.c
index 381e6ae4ef..8b9b6abb93 100644
--- a/src/backend/executor/instrument.c
+++ b/src/backend/executor/instrument.c
@@ -7,7 +7,7 @@
  * Copyright (c) 2001-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/instrument.c,v 1.9 2005/01/01 05:43:06 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/instrument.c,v 1.10 2005/03/20 22:27:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -36,29 +36,30 @@ InstrStartNode(Instrumentation *instr)
 	if (!instr)
 		return;
 
-	if (instr->starttime.tv_sec != 0 || instr->starttime.tv_usec != 0)
+	if (!INSTR_TIME_IS_ZERO(instr->starttime))
 		elog(DEBUG2, "InstrStartNode called twice in a row");
 	else
-		gettimeofday(&instr->starttime, NULL);
+		INSTR_TIME_SET_CURRENT(instr->starttime);
 }
 
 /* Exit from a plan node */
 void
 InstrStopNode(Instrumentation *instr, bool returnedTuple)
 {
-	struct timeval endtime;
+	instr_time endtime;
 
 	if (!instr)
 		return;
 
-	if (instr->starttime.tv_sec == 0 && instr->starttime.tv_usec == 0)
+	if (INSTR_TIME_IS_ZERO(instr->starttime))
 	{
 		elog(DEBUG2, "InstrStopNode without start");
 		return;
 	}
 
-	gettimeofday(&endtime, NULL);
+	INSTR_TIME_SET_CURRENT(endtime);
 
+#ifndef WIN32
 	instr->counter.tv_sec += endtime.tv_sec - instr->starttime.tv_sec;
 	instr->counter.tv_usec += endtime.tv_usec - instr->starttime.tv_usec;
 
@@ -73,16 +74,17 @@ InstrStopNode(Instrumentation *instr, bool returnedTuple)
 		instr->counter.tv_usec -= 1000000;
 		instr->counter.tv_sec++;
 	}
+#else /* WIN32 */
+	instr->counter.QuadPart += (endtime.QuadPart - instr->starttime.QuadPart);
+#endif
 
-	instr->starttime.tv_sec = 0;
-	instr->starttime.tv_usec = 0;
+	INSTR_TIME_SET_ZERO(instr->starttime);
 
 	/* 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;
+		instr->firsttuple = INSTR_TIME_GET_DOUBLE(instr->counter);
 	}
 
 	if (returnedTuple)
@@ -103,8 +105,7 @@ InstrEndLoop(Instrumentation *instr)
 		return;
 
 	/* Accumulate statistics */
-	totaltime = (double) instr->counter.tv_sec +
-		(double) instr->counter.tv_usec / 1000000.0;
+	totaltime = INSTR_TIME_GET_DOUBLE(instr->counter);
 
 	instr->startup += instr->firsttuple;
 	instr->total += totaltime;
@@ -113,10 +114,8 @@ InstrEndLoop(Instrumentation *instr)
 
 	/* 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_TIME_SET_ZERO(instr->starttime);
+	INSTR_TIME_SET_ZERO(instr->counter);
 	instr->firsttuple = 0;
 	instr->tuplecount = 0;
 }
diff --git a/src/include/executor/instrument.h b/src/include/executor/instrument.h
index 754655c1fd..8936c5cce2 100644
--- a/src/include/executor/instrument.h
+++ b/src/include/executor/instrument.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 2001-2005, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/include/executor/instrument.h,v 1.8 2005/01/01 05:43:09 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/executor/instrument.h,v 1.9 2005/03/20 22:27:52 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,12 +16,51 @@
 #include <sys/time.h>
 
 
+/*
+ * gettimeofday() does not have sufficient resolution on Windows,
+ * so we must use QueryPerformanceCounter() instead.  These macros
+ * also give some breathing room to use other high-precision-timing APIs
+ * on yet other platforms.  (The macro-ization is not complete, however;
+ * see subtraction code in instrument.c and explain.c.)
+ */
+#ifndef WIN32
+
+typedef struct timeval instr_time;
+
+#define INSTR_TIME_IS_ZERO(t)	((t).tv_sec == 0 && (t).tv_usec == 0)
+#define INSTR_TIME_SET_ZERO(t)	((t).tv_sec = 0, (t).tv_usec = 0)
+#define INSTR_TIME_SET_CURRENT(t)	gettimeofday(&(t), NULL)
+#define INSTR_TIME_GET_DOUBLE(t) \
+	(((double) (t).tv_sec) + ((double) (t).tv_usec) / 1000000.0)
+
+#else  /* WIN32 */
+
+typedef LARGE_INTEGER instr_time;
+
+#define INSTR_TIME_IS_ZERO(t)	((t).QuadPart == 0)
+#define INSTR_TIME_SET_ZERO(t)	((t).QuadPart = 0)
+#define INSTR_TIME_SET_CURRENT(t)	QueryPerformanceCounter(&(t))
+#define INSTR_TIME_GET_DOUBLE(t) \
+	(((double) (t).QuadPart) / GetTimerFrequency())
+
+static __inline__ double
+GetTimerFrequency(void)
+{
+	LARGE_INTEGER f;
+
+	QueryPerformanceFrequency(&f);
+	return (double) f.QuadPart;
+}
+
+#endif /* WIN32 */
+
+
 typedef struct Instrumentation
 {
 	/* Info about current plan cycle: */
 	bool		running;		/* TRUE if we've completed first tuple */
-	struct timeval starttime;	/* Start time of current iteration of node */
-	struct timeval counter;		/* Accumulates runtime for this node */
+	instr_time	starttime;		/* Start time of current iteration of node */
+	instr_time	counter;		/* Accumulates runtime for this node */
 	double		firsttuple;		/* Time for first tuple of this cycle */
 	double		tuplecount;		/* Tuples so far this cycle */
 	/* Accumulated statistics across all completed cycles: */