Add auto-explain contrib module for automatic logging of the plans of
slow-running queries. Takahiro Itagaki
This commit is contained in:
Tom Lane
parent
31ec957a15
commit
e125e28e78
@ -1,4 +1,4 @@
|
||||
# $PostgreSQL: pgsql/contrib/Makefile,v 1.84 2008/07/29 18:31:20 tgl Exp $
|
||||
# $PostgreSQL: pgsql/contrib/Makefile,v 1.85 2008/11/19 02:59:28 tgl Exp $
|
||||
|
||||
subdir = contrib
|
||||
top_builddir = ..
|
||||
@ -6,6 +6,7 @@ include $(top_builddir)/src/Makefile.global
|
||||
|
||||
WANTED_DIRS = \
|
||||
adminpack \
|
||||
auto_explain \
|
||||
btree_gist \
|
||||
chkpass \
|
||||
citext \
|
||||
|
||||
@ -28,6 +28,10 @@ adminpack -
|
||||
File and log manipulation routines, used by pgAdmin
|
||||
by Dave Page <dpage@vale-housing.co.uk>
|
||||
|
||||
auto_explain -
|
||||
Log EXPLAIN output for long-running queries
|
||||
by Takahiro Itagaki <itagaki.takahiro@oss.ntt.co.jp>
|
||||
|
||||
btree_gist -
|
||||
Support for emulating BTREE indexing in GiST
|
||||
by Oleg Bartunov <oleg@sai.msu.su> and Teodor Sigaev <teodor@sigaev.ru>
|
||||
|
||||
15
contrib/auto_explain/Makefile
Normal file
15
contrib/auto_explain/Makefile
Normal file
@ -0,0 +1,15 @@
|
||||
# $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
228
contrib/auto_explain/auto_explain.c
Normal file
@ -0,0 +1,228 @@
|
||||
/*-------------------------------------------------------------------------
|
||||
*
|
||||
* 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);
|
||||
}
|
||||
176
doc/src/sgml/auto-explain.sgml
Normal file
176
doc/src/sgml/auto-explain.sgml
Normal file
@ -0,0 +1,176 @@
|
||||
<!-- $PostgreSQL: pgsql/doc/src/sgml/auto-explain.sgml,v 1.1 2008/11/19 02:59:28 tgl Exp $ -->
|
||||
|
||||
<sect1 id="auto-explain">
|
||||
<title>auto_explain</title>
|
||||
|
||||
<indexterm zone="auto-explain">
|
||||
<primary>auto_explain</primary>
|
||||
</indexterm>
|
||||
|
||||
<para>
|
||||
The <filename>auto_explain</filename> module provides a means for
|
||||
logging execution plans of slow statements automatically, without
|
||||
having to run <xref linkend="sql-explain" endterm="sql-explain-title">
|
||||
by hand. This is especially helpful for tracking down un-optimized queries
|
||||
in large applications.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
The module provides no SQL-accessible functions. To use it, simply
|
||||
load it into the server. You can load it into an individual session:
|
||||
|
||||
<programlisting>
|
||||
LOAD 'auto_explain';
|
||||
</programlisting>
|
||||
|
||||
(You must be superuser to do that.) More typical usage is to preload
|
||||
it into all sessions by including <literal>auto_explain</> in
|
||||
<xref linkend="guc-shared-preload-libraries"> in
|
||||
<filename>postgresql.conf</>. Then you can track unexpectedly slow queries
|
||||
no matter when they happen. Of course there is a price in overhead for
|
||||
that.
|
||||
</para>
|
||||
|
||||
<sect2>
|
||||
<title>Configuration parameters</title>
|
||||
|
||||
<para>
|
||||
There are several configuration parameters that control the behavior of
|
||||
<filename>auto_explain</filename>. Note that the default behavior is
|
||||
to do nothing, so you must set at least
|
||||
<varname>explain.log_min_duration</varname> if you want any results.
|
||||
</para>
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term>
|
||||
<varname>explain.log_min_duration</varname> (<type>integer</type>)
|
||||
</term>
|
||||
<indexterm>
|
||||
<primary><varname>explain.log_min_duration</> configuration parameter</primary>
|
||||
</indexterm>
|
||||
<listitem>
|
||||
<para>
|
||||
<varname>explain.log_min_duration</varname> is the minimum statement
|
||||
execution time, in milliseconds, that will cause the statement's plan to
|
||||
be logged. Setting this to zero logs all plans. Minus-one (the default)
|
||||
disables logging of plans. For example, if you set it to
|
||||
<literal>250ms</literal> then all statements that run 250ms or longer
|
||||
will be logged. Only superusers can change this setting.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
<varname>explain.log_analyze</varname> (<type>boolean</type>)
|
||||
</term>
|
||||
<indexterm>
|
||||
<primary><varname>explain.log_analyze</> configuration parameter</primary>
|
||||
</indexterm>
|
||||
<listitem>
|
||||
<para>
|
||||
<varname>explain.log_analyze</varname> causes <command>EXPLAIN ANALYZE</>
|
||||
output, rather than just <command>EXPLAIN</> output, to be printed
|
||||
when an execution plan is logged. This parameter is off by default.
|
||||
Only superusers can change this setting.
|
||||
</para>
|
||||
<note>
|
||||
<para>
|
||||
When this parameter is on, per-plan-node timing occurs for all
|
||||
statements executed, whether or not they run long enough to actually
|
||||
get logged. This can have extremely negative impact on performance.
|
||||
</para>
|
||||
</note>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
<varname>explain.log_verbose</varname> (<type>boolean</type>)
|
||||
</term>
|
||||
<indexterm>
|
||||
<primary><varname>explain.log_verbose</> configuration parameter</primary>
|
||||
</indexterm>
|
||||
<listitem>
|
||||
<para>
|
||||
<varname>explain.log_verbose</varname> causes <command>EXPLAIN VERBOSE</>
|
||||
output, rather than just <command>EXPLAIN</> output, to be printed
|
||||
when an execution plan is logged. This parameter is off by default.
|
||||
Only superusers can change this setting.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
<varname>explain.log_nested_statements</varname> (<type>boolean</type>)
|
||||
</term>
|
||||
<indexterm>
|
||||
<primary><varname>explain.log_nested_statements</> configuration parameter</primary>
|
||||
</indexterm>
|
||||
<listitem>
|
||||
<para>
|
||||
<varname>explain.log_nested_statements</varname> causes nested
|
||||
statements (statements executed inside a function) to be considered
|
||||
for logging. When it is off, only top-level query plans are logged. This
|
||||
parameter is off by default. Only superusers can change this setting.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
</variablelist>
|
||||
|
||||
<para>
|
||||
In order to set these parameters in your <filename>postgresql.conf</> file,
|
||||
you will need to add <literal>explain</> in
|
||||
<varname>custom_variable_classes</>. Typical usage might be:
|
||||
</para>
|
||||
|
||||
<programlisting>
|
||||
# postgresql.conf
|
||||
shared_preload_libraries = 'auto_explain'
|
||||
|
||||
custom_variable_classes = 'explain'
|
||||
explain.log_min_duration = '3s'
|
||||
</programlisting>
|
||||
</sect2>
|
||||
|
||||
<sect2>
|
||||
<title>Example</title>
|
||||
|
||||
<programlisting>
|
||||
postgres=# LOAD 'auto_explain';
|
||||
postgres=# SET explain.log_min_duration = 0;
|
||||
postgres=# SELECT count(*)
|
||||
FROM pg_class, pg_index
|
||||
WHERE oid = indrelid AND indisunique;
|
||||
</programlisting>
|
||||
|
||||
<para>
|
||||
This might produce log output such as:
|
||||
</para>
|
||||
|
||||
<programlisting>
|
||||
LOG: duration: 0.986 ms plan:
|
||||
Aggregate (cost=14.90..14.91 rows=1 width=0)
|
||||
-> Hash Join (cost=3.91..14.70 rows=81 width=0)
|
||||
Hash Cond: (pg_class.oid = pg_index.indrelid)
|
||||
-> Seq Scan on pg_class (cost=0.00..8.27 rows=227 width=4)
|
||||
-> Hash (cost=2.90..2.90 rows=81 width=4)
|
||||
-> Seq Scan on pg_index (cost=0.00..2.90 rows=81 width=4)
|
||||
Filter: indisunique
|
||||
STATEMENT: SELECT count(*)
|
||||
FROM pg_class, pg_index
|
||||
WHERE oid = indrelid AND indisunique;
|
||||
</programlisting>
|
||||
</sect2>
|
||||
|
||||
<sect2>
|
||||
<title>Author</title>
|
||||
|
||||
<para>
|
||||
Takahiro Itagaki <email>itagaki.takahiro@oss.ntt.co.jp</email>
|
||||
</para>
|
||||
</sect2>
|
||||
|
||||
</sect1>
|
||||
@ -1,4 +1,4 @@
|
||||
<!-- $PostgreSQL: pgsql/doc/src/sgml/contrib.sgml,v 1.9 2008/07/29 18:31:20 tgl Exp $ -->
|
||||
<!-- $PostgreSQL: pgsql/doc/src/sgml/contrib.sgml,v 1.10 2008/11/19 02:59:28 tgl Exp $ -->
|
||||
|
||||
<appendix id="contrib">
|
||||
<title>Additional Supplied Modules</title>
|
||||
@ -79,6 +79,7 @@ psql -d dbname -f <replaceable>SHAREDIR</>/contrib/<replaceable>module</>.sql
|
||||
</para>
|
||||
|
||||
&adminpack;
|
||||
&auto-explain;
|
||||
&btree-gist;
|
||||
&chkpass;
|
||||
&citext;
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
<!-- $PostgreSQL: pgsql/doc/src/sgml/filelist.sgml,v 1.57 2008/07/29 18:31:20 tgl Exp $ -->
|
||||
<!-- $PostgreSQL: pgsql/doc/src/sgml/filelist.sgml,v 1.58 2008/11/19 02:59:28 tgl Exp $ -->
|
||||
|
||||
<!entity history SYSTEM "history.sgml">
|
||||
<!entity info SYSTEM "info.sgml">
|
||||
@ -92,6 +92,7 @@
|
||||
<!-- contrib information -->
|
||||
<!entity contrib SYSTEM "contrib.sgml">
|
||||
<!entity adminpack SYSTEM "adminpack.sgml">
|
||||
<!entity auto-explain SYSTEM "auto-explain.sgml">
|
||||
<!entity btree-gist SYSTEM "btree-gist.sgml">
|
||||
<!entity chkpass SYSTEM "chkpass.sgml">
|
||||
<!entity citext SYSTEM "citext.sgml">
|
||||
|
||||
Loading…
Reference in New Issue
Block a user