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Add auto-explain contrib module for automatic logging of the plans of

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slow-running queries.

Takahiro Itagaki
This commit is contained in:
Tom Lane
2008-11-19 02:59:28 +00:00
parent 31ec957a15
commit e125e28e78
7 changed files with 429 additions and 3 deletions
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15
contrib/auto_explain/Makefile Normal file
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# $PostgreSQL: pgsql/contrib/auto_explain/Makefile,v 1.1 2008/11/19 02:59:28 tgl Exp $
MODULE_big = auto_explain
OBJS = auto_explain.o
ifdef USE_PGXS
PG_CONFIG = pg_config
PGXS := $(shell $(PG_CONFIG) --pgxs)
include $(PGXS)
else
subdir = contrib/auto_explain
top_builddir = ../..
include $(top_builddir)/src/Makefile.global
include $(top_srcdir)/contrib/contrib-global.mk
endif

228
contrib/auto_explain/auto_explain.c Normal file
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/*-------------------------------------------------------------------------
*
* auto_explain.c
*
*
* Copyright (c) 2008, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/contrib/auto_explain/auto_explain.c,v 1.1 2008/11/19 02:59:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "commands/explain.h"
#include "executor/instrument.h"
#include "utils/guc.h"
PG_MODULE_MAGIC;
#define GUCNAME(name) ("explain." name)
/* GUC variables */
static int explain_log_min_duration = -1; /* msec or -1 */
static bool explain_log_analyze = false;
static bool explain_log_verbose = false;
static bool explain_log_nested = false;
/* Current nesting depth of ExecutorRun calls */
static int nesting_level = 0;
/* Saved hook values in case of unload */
static ExecutorStart_hook_type prev_ExecutorStart = NULL;
static ExecutorRun_hook_type prev_ExecutorRun = NULL;
static ExecutorEnd_hook_type prev_ExecutorEnd = NULL;
#define auto_explain_enabled() \
(explain_log_min_duration >= 0 && \
(nesting_level == 0 || explain_log_nested))
void _PG_init(void);
void _PG_fini(void);
static void explain_ExecutorStart(QueryDesc *queryDesc, int eflags);
static void explain_ExecutorRun(QueryDesc *queryDesc,
ScanDirection direction,
long count);
static void explain_ExecutorEnd(QueryDesc *queryDesc);
/*
* Module load callback
*/
void
_PG_init(void)
{
/* Define custom GUC variables. */
DefineCustomIntVariable(GUCNAME("log_min_duration"),
"Sets the minimum execution time above which plans will be logged.",
"Zero prints all plans. -1 turns this feature off.",
&explain_log_min_duration,
-1,
-1, INT_MAX / 1000,
PGC_SUSET,
GUC_UNIT_MS,
NULL,
NULL);
DefineCustomBoolVariable(GUCNAME("log_analyze"),
"Use EXPLAIN ANALYZE for plan logging.",
NULL,
&explain_log_analyze,
false,
PGC_SUSET,
0,
NULL,
NULL);
DefineCustomBoolVariable(GUCNAME("log_verbose"),
"Use EXPLAIN VERBOSE for plan logging.",
NULL,
&explain_log_verbose,
false,
PGC_SUSET,
0,
NULL,
NULL);
DefineCustomBoolVariable(GUCNAME("log_nested_statements"),
"Log nested statements.",
NULL,
&explain_log_nested,
false,
PGC_SUSET,
0,
NULL,
NULL);
/* Install hooks. */
prev_ExecutorStart = ExecutorStart_hook;
ExecutorStart_hook = explain_ExecutorStart;
prev_ExecutorRun = ExecutorRun_hook;
ExecutorRun_hook = explain_ExecutorRun;
prev_ExecutorEnd = ExecutorEnd_hook;
ExecutorEnd_hook = explain_ExecutorEnd;
}
/*
* Module unload callback
*/
void
_PG_fini(void)
{
/* Uninstall hooks. */
ExecutorStart_hook = prev_ExecutorStart;
ExecutorRun_hook = prev_ExecutorRun;
ExecutorEnd_hook = prev_ExecutorEnd;
}
/*
* ExecutorStart hook: start up logging if needed
*/
void
explain_ExecutorStart(QueryDesc *queryDesc, int eflags)
{
if (auto_explain_enabled())
{
/* Enable per-node instrumentation iff log_analyze is required. */
if (explain_log_analyze && (eflags & EXEC_FLAG_EXPLAIN_ONLY) == 0)
queryDesc->doInstrument = true;
}
if (prev_ExecutorStart)
prev_ExecutorStart(queryDesc, eflags);
else
standard_ExecutorStart(queryDesc, eflags);
if (auto_explain_enabled())
{
/*
* Set up to track total elapsed time in ExecutorRun. Make sure
* the space is allocated in the per-query context so it will go
* away at ExecutorEnd.
*/
if (queryDesc->totaltime == NULL)
{
MemoryContext oldcxt;
oldcxt = MemoryContextSwitchTo(queryDesc->estate->es_query_cxt);
queryDesc->totaltime = InstrAlloc(1);
MemoryContextSwitchTo(oldcxt);
}
}
}
/*
* ExecutorRun hook: all we need do is track nesting depth
*/
void
explain_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, long count)
{
nesting_level++;
PG_TRY();
{
if (prev_ExecutorRun)
prev_ExecutorRun(queryDesc, direction, count);
else
standard_ExecutorRun(queryDesc, direction, count);
nesting_level--;
}
PG_CATCH();
{
nesting_level--;
PG_RE_THROW();
}
PG_END_TRY();
}
/*
* ExecutorEnd hook: log results if needed
*/
void
explain_ExecutorEnd(QueryDesc *queryDesc)
{
if (queryDesc->totaltime && auto_explain_enabled())
{
double msec;
/*
* Make sure stats accumulation is done. (Note: it's okay if
* several levels of hook all do this.)
*/
InstrEndLoop(queryDesc->totaltime);
/* Log plan if duration is exceeded. */
msec = queryDesc->totaltime->total * 1000.0;
if (msec >= explain_log_min_duration)
{
StringInfoData buf;
initStringInfo(&buf);
ExplainPrintPlan(&buf, queryDesc,
queryDesc->doInstrument && explain_log_analyze,
explain_log_verbose);
/* Remove last line break */
if (buf.len > 0 && buf.data[buf.len - 1] == '\n')
buf.data[--buf.len] = '\0';
/*
* Note: we rely on the existing logging of context or
* debug_query_string to identify just which statement is being
* reported. This isn't ideal but trying to do it here would
* often result in duplication.
*/
ereport(LOG,
(errmsg("duration: %.3f ms plan:\n%s",
msec, buf.data)));
pfree(buf.data);
}
}
if (prev_ExecutorEnd)
prev_ExecutorEnd(queryDesc);
else
standard_ExecutorEnd(queryDesc);
}