From 31f579f09ccdaaa63a65bdfba9a9803c4f563a98 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 20 May 2014 12:20:57 -0400
Subject: [PATCH] Prevent auto_explain from changing the output of a user's
EXPLAIN.
Commit af7914c6627bcf0b0ca614e9ce95d3f8056602bf, 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.
---
src/backend/commands/explain.c | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index a8e6bb56afe..ae5bde754c7 100644
--- 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;
--
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