Prevent auto_explain from changing the output of a user's EXPLAIN.

tglsfdc · tglsfdc · commit 31f579f09ccd · 2014-05-20T12:20:57.000-04:00
Commit af7914c, which introduced the EXPLAIN (TIMING) option, for some reason coded explain.c to look at planstate->instrument->need_timer rather than es->timing to decide whether to print timing info. However, the former flag might get set as a result of contrib/auto_explain wanting timing information. We certainly don't want activation of auto_explain to change user-visible statement behavior, so fix that. Also fix an independent bug introduced in the same patch: in the code path for a never-executed node with a machine-friendly output format, if timing was selected, it would fail to print the Actual Rows and Actual Loops items. Per bug #10404 from Tomonari Katsumata. Back-patch to 9.2 where the faulty code was introduced.
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
@@ -1006,11 +1006,18 @@ ExplainNode(PlanState *planstate, List *ancestors,
 	/*
 	 * We have to forcibly clean up the instrumentation state because we
 	 * haven't done ExecutorEnd yet.  This is pretty grotty ...
+	 *
+	 * Note: contrib/auto_explain could cause instrumentation to be set up
+	 * even though we didn't ask for it here.  Be careful not to print any
+	 * instrumentation results the user didn't ask for.  But we do the
+	 * InstrEndLoop call anyway, if possible, to reduce the number of cases
+	 * auto_explain has to contend with.
 	 */
 	if (planstate->instrument)
 		InstrEndLoop(planstate->instrument);
 
-	if (planstate->instrument && planstate->instrument->nloops > 0)
+	if (es->analyze &&
+		planstate->instrument && planstate->instrument->nloops > 0)
 	{
 		double		nloops = planstate->instrument->nloops;
 		double		startup_sec = 1000.0 * planstate->instrument->startup / nloops;
@@ -1019,7 +1026,7 @@ ExplainNode(PlanState *planstate, List *ancestors,
 
 		if (es->format == EXPLAIN_FORMAT_TEXT)
 		{
-			if (planstate->instrument->need_timer)
+			if (es->timing)
 				appendStringInfo(es->str,
 							" (actual time=%.3f..%.3f rows=%.0f loops=%.0f)",
 								 startup_sec, total_sec, rows, nloops);
@@ -1030,7 +1037,7 @@ ExplainNode(PlanState *planstate, List *ancestors,
 		}
 		else
 		{
-			if (planstate->instrument->need_timer)
+			if (es->timing)
 			{
 				ExplainPropertyFloat("Actual Startup Time", startup_sec, 3, es);
 				ExplainPropertyFloat("Actual Total Time", total_sec, 3, es);
@@ -1041,20 +1048,18 @@ ExplainNode(PlanState *planstate, List *ancestors,
 	}
 	else if (es->analyze)
 	{
-
 		if (es->format == EXPLAIN_FORMAT_TEXT)
 			appendStringInfo(es->str, " (never executed)");
-		else if (planstate->instrument->need_timer)
-		{
-			ExplainPropertyFloat("Actual Startup Time", 0.0, 3, es);
-			ExplainPropertyFloat("Actual Total Time", 0.0, 3, es);
-		}
 		else
 		{
+			if (es->timing)
+			{
+				ExplainPropertyFloat("Actual Startup Time", 0.0, 3, es);
+				ExplainPropertyFloat("Actual Total Time", 0.0, 3, es);
+			}
 			ExplainPropertyFloat("Actual Rows", 0.0, 0, es);
 			ExplainPropertyFloat("Actual Loops", 0.0, 0, es);
 		}
-
 	}
 
 	/* in text format, first line ends here */
@@ -1220,7 +1225,7 @@ ExplainNode(PlanState *planstate, List *ancestors,
 	}
 
 	/* Show buffer usage */
-	if (es->buffers)
+	if (es->buffers && planstate->instrument)
 	{
 		const BufferUsage *usage = &planstate->instrument->bufusage;
 

Original file line number	Diff line number	Diff line change
`@@ -1006,11 +1006,18 @@ ExplainNode(PlanState planstate, List ancestors,`
`1006`	`1006`	`/*`
`1007`	`1007`	`* We have to forcibly clean up the instrumentation state because we`
`1008`	`1008`	`* haven't done ExecutorEnd yet. This is pretty grotty ...`
	`1009`	`+ *`
	`1010`	`+ * Note: contrib/auto_explain could cause instrumentation to be set up`
	`1011`	`+ * even though we didn't ask for it here. Be careful not to print any`
	`1012`	`+ * instrumentation results the user didn't ask for. But we do the`
	`1013`	`+ * InstrEndLoop call anyway, if possible, to reduce the number of cases`
	`1014`	`+ * auto_explain has to contend with.`
`1009`	`1015`	`*/`
`1010`	`1016`	`if (planstate->instrument)`
`1011`	`1017`	`InstrEndLoop(planstate->instrument);`
`1012`	`1018`
`1013`		`- if (planstate->instrument && planstate->instrument->nloops > 0)`
	`1019`	`+ if (es->analyze &&`
	`1020`	`+ planstate->instrument && planstate->instrument->nloops > 0)`
`1014`	`1021`	`{`
`1015`	`1022`	`double nloops = planstate->instrument->nloops;`
`1016`	`1023`	`double startup_sec = 1000.0 * planstate->instrument->startup / nloops;`
`@@ -1019,7 +1026,7 @@ ExplainNode(PlanState planstate, List ancestors,`
`1019`	`1026`
`1020`	`1027`	`if (es->format == EXPLAIN_FORMAT_TEXT)`
`1021`	`1028`	`{`
`1022`		`- if (planstate->instrument->need_timer)`
	`1029`	`+ if (es->timing)`
`1023`	`1030`	`appendStringInfo(es->str,`
`1024`	`1031`	`" (actual time=%.3f..%.3f rows=%.0f loops=%.0f)",`
`1025`	`1032`	`startup_sec, total_sec, rows, nloops);`
`@@ -1030,7 +1037,7 @@ ExplainNode(PlanState planstate, List ancestors,`
`1030`	`1037`	`}`
`1031`	`1038`	`else`
`1032`	`1039`	`{`
`1033`		`- if (planstate->instrument->need_timer)`
	`1040`	`+ if (es->timing)`
`1034`	`1041`	`{`
`1035`	`1042`	`ExplainPropertyFloat("Actual Startup Time", startup_sec, 3, es);`
`1036`	`1043`	`ExplainPropertyFloat("Actual Total Time", total_sec, 3, es);`
`@@ -1041,20 +1048,18 @@ ExplainNode(PlanState planstate, List ancestors,`
`1041`	`1048`	`}`
`1042`	`1049`	`else if (es->analyze)`
`1043`	`1050`	`{`
`1044`		`-`
`1045`	`1051`	`if (es->format == EXPLAIN_FORMAT_TEXT)`
`1046`	`1052`	`appendStringInfo(es->str, " (never executed)");`
`1047`		`- else if (planstate->instrument->need_timer)`
`1048`		`- {`
`1049`		`- ExplainPropertyFloat("Actual Startup Time", 0.0, 3, es);`
`1050`		`- ExplainPropertyFloat("Actual Total Time", 0.0, 3, es);`
`1051`		`- }`
`1052`	`1053`	`else`
`1053`	`1054`	`{`
	`1055`	`+ if (es->timing)`
	`1056`	`+ {`
	`1057`	`+ ExplainPropertyFloat("Actual Startup Time", 0.0, 3, es);`
	`1058`	`+ ExplainPropertyFloat("Actual Total Time", 0.0, 3, es);`
	`1059`	`+ }`
`1054`	`1060`	`ExplainPropertyFloat("Actual Rows", 0.0, 0, es);`
`1055`	`1061`	`ExplainPropertyFloat("Actual Loops", 0.0, 0, es);`
`1056`	`1062`	`}`
`1057`		`-`
`1058`	`1063`	`}`
`1059`	`1064`
`1060`	`1065`	`/* in text format, first line ends here */`
`@@ -1220,7 +1225,7 @@ ExplainNode(PlanState planstate, List ancestors,`
`1220`	`1225`	`}`
`1221`	`1226`
`1222`	`1227`	`/* Show buffer usage */`
`1223`		`- if (es->buffers)`
	`1228`	`+ if (es->buffers && planstate->instrument)`
`1224`	`1229`	`{`
`1225`	`1230`	`const BufferUsage *usage = &planstate->instrument->bufusage;`
`1226`	`1231`