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Move pgstat.tmp into a temporary directory under $PGDATA named pg_stat_tmp. 

This allows the use of a ramdrive (either through mount or symlink) for
the temporary file that's written every half second, which should
reduce I/O.

On server shutdown/startup, the file is written to the old location in
the global directory, to preserve data across restarts.

Bump catversion since the $PGDATA directory layout changed.
This commit is contained in:
Magnus Hagander 2008-08-05 12:09:30 +00:00
parent 7e61edf2e7
commit 70d756970b
5 changed files with 62 additions and 28 deletions
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13
doc/src/sgml/monitoring.sgml
View File

@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.60 2008/06/18 17:44:12 neilc Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.61 2008/08/05 12:09:30 mha Exp $ -->
<chapter id="monitoring">
<title>Monitoring Database Activity</title>
@ -164,6 +164,17 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
only superusers are allowed to change these parameters with
<command>SET</>.)
</para>
<para>
The statistics collector communicates with the backends needing
information (including autovacuum) through temporary files.
These files are stored in the <filename>pg_stat_tmp</filename> subdirectory.
When the postmaster shuts down, a permanent copy of the statistics
data is stored in the <filename>global</filename> subdirectory. For increased
performance, it is possible to mount or symlink a RAM based
filesystem to the <filename>pg_stat_tmp</filename> directory.
</para>
</sect2>
<sect2 id="monitoring-stats-views">

8
doc/src/sgml/storage.sgml
View File

@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.23 2008/05/02 01:08:26 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.24 2008/08/05 12:09:30 mha Exp $ -->
<chapter id="storage">
@ -77,6 +77,12 @@ Item
(used for shared row locks)</entry>
</row>
<row>
<entry><filename>pg_stat_tmp</></entry>
<entry>Subdirectory containing temporary files for the statistics
subsystem</entry>
</row>
<row>
<entry><filename>pg_subtrans</></entry>
<entry>Subdirectory containing subtransaction status data</entry>

60
src/backend/postmaster/pgstat.c
View File

@ -13,7 +13,7 @@
*
* Copyright (c) 2001-2008, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.177 2008/08/01 13:16:08 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.178 2008/08/05 12:09:30 mha Exp $
* ----------
*/
#include "postgres.h"
@ -68,8 +68,10 @@
* Paths for the statistics files (relative to installation's $PGDATA).
* ----------
*/
#define PGSTAT_STAT_FILENAME "global/pgstat.stat"
#define PGSTAT_STAT_TMPFILE "global/pgstat.tmp"
#define PGSTAT_STAT_PERMANENT_FILENAME "global/pgstat.stat"
#define PGSTAT_STAT_PERMANENT_TMPFILE "global/pgstat.tmp"
#define PGSTAT_STAT_FILENAME "pg_stat_tmp/pgstat.stat"
#define PGSTAT_STAT_TMPFILE "pg_stat_tmp/pgstat.tmp"
/* ----------
* Timer definitions.
@ -219,8 +221,8 @@ static void force_statwrite(SIGNAL_ARGS);
static void pgstat_beshutdown_hook(int code, Datum arg);
static PgStat_StatDBEntry *pgstat_get_db_entry(Oid databaseid, bool create);
static void pgstat_write_statsfile(void);
static HTAB *pgstat_read_statsfile(Oid onlydb);
static void pgstat_write_statsfile(bool permanent);
static HTAB *pgstat_read_statsfile(Oid onlydb, bool permanent);
static void backend_read_statsfile(void);
static void pgstat_read_current_status(void);
@ -510,6 +512,7 @@ void
pgstat_reset_all(void)
{
unlink(PGSTAT_STAT_FILENAME);
unlink(PGSTAT_STAT_PERMANENT_FILENAME);
}
#ifdef EXEC_BACKEND
@ -2598,7 +2601,7 @@ PgstatCollectorMain(int argc, char *argv[])
* zero.
*/
pgStatRunningInCollector = true;
pgStatDBHash = pgstat_read_statsfile(InvalidOid);
pgStatDBHash = pgstat_read_statsfile(InvalidOid, true);
/*
* Setup the descriptor set for select(2). Since only one bit in the set
@ -2638,7 +2641,7 @@ PgstatCollectorMain(int argc, char *argv[])
if (!PostmasterIsAlive(true))
break;
pgstat_write_statsfile();
pgstat_write_statsfile(false);
need_statwrite = false;
need_timer = true;
}
@ -2806,7 +2809,7 @@ PgstatCollectorMain(int argc, char *argv[])
/*
* Save the final stats to reuse at next startup.
*/
pgstat_write_statsfile();
pgstat_write_statsfile(true);
exit(0);
}
@ -2891,10 +2894,14 @@ pgstat_get_db_entry(Oid databaseid, bool create)
* pgstat_write_statsfile() -
*
* Tell the news.
* If writing to the permanent file (happens when the collector is
* shutting down only), remove the temporary file so that backends
* starting up under a new postmaster can't read the old data before
* the new collector is ready.
* ----------
*/
static void
pgstat_write_statsfile(void)
pgstat_write_statsfile(bool permanent)
{
HASH_SEQ_STATUS hstat;
HASH_SEQ_STATUS tstat;
@ -2904,17 +2911,19 @@ pgstat_write_statsfile(void)
PgStat_StatFuncEntry *funcentry;
FILE *fpout;
int32 format_id;
const char *tmpfile = permanent?PGSTAT_STAT_PERMANENT_TMPFILE:PGSTAT_STAT_TMPFILE;
const char *statfile = permanent?PGSTAT_STAT_PERMANENT_FILENAME:PGSTAT_STAT_FILENAME;
/*
* Open the statistics temp file to write out the current values.
*/
fpout = fopen(PGSTAT_STAT_TMPFILE, PG_BINARY_W);
fpout = fopen(tmpfile, PG_BINARY_W);
if (fpout == NULL)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not open temporary statistics file \"%s\": %m",
PGSTAT_STAT_TMPFILE)));
tmpfile)));
return;
}
@ -2981,26 +2990,29 @@ pgstat_write_statsfile(void)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write temporary statistics file \"%s\": %m",
PGSTAT_STAT_TMPFILE)));
tmpfile)));
fclose(fpout);
unlink(PGSTAT_STAT_TMPFILE);
unlink(tmpfile);
}
else if (fclose(fpout) < 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not close temporary statistics file \"%s\": %m",
PGSTAT_STAT_TMPFILE)));
unlink(PGSTAT_STAT_TMPFILE);
tmpfile)));
unlink(tmpfile);
}
else if (rename(PGSTAT_STAT_TMPFILE, PGSTAT_STAT_FILENAME) < 0)
else if (rename(tmpfile, statfile) < 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not rename temporary statistics file \"%s\" to \"%s\": %m",
PGSTAT_STAT_TMPFILE, PGSTAT_STAT_FILENAME)));
unlink(PGSTAT_STAT_TMPFILE);
tmpfile, statfile)));
unlink(tmpfile);
}
if (permanent)
unlink(PGSTAT_STAT_FILENAME);
}
@ -3012,7 +3024,7 @@ pgstat_write_statsfile(void)
* ----------
*/
static HTAB *
pgstat_read_statsfile(Oid onlydb)
pgstat_read_statsfile(Oid onlydb, bool permanent)
{
PgStat_StatDBEntry *dbentry;
PgStat_StatDBEntry dbbuf;
@ -3027,6 +3039,7 @@ pgstat_read_statsfile(Oid onlydb)
FILE *fpin;
int32 format_id;
bool found;
const char *statfile = permanent?PGSTAT_STAT_PERMANENT_FILENAME:PGSTAT_STAT_FILENAME;
/*
* The tables will live in pgStatLocalContext.
@ -3055,7 +3068,7 @@ pgstat_read_statsfile(Oid onlydb)
* return zero for anything and the collector simply starts from scratch
* with empty counters.
*/
if ((fpin = AllocateFile(PGSTAT_STAT_FILENAME, PG_BINARY_R)) == NULL)
if ((fpin = AllocateFile(statfile, PG_BINARY_R)) == NULL)
return dbhash;
/*
@ -3244,6 +3257,9 @@ pgstat_read_statsfile(Oid onlydb)
done:
FreeFile(fpin);
if (permanent)
unlink(PGSTAT_STAT_PERMANENT_FILENAME);
return dbhash;
}
@ -3262,9 +3278,9 @@ backend_read_statsfile(void)
/* Autovacuum launcher wants stats about all databases */
if (IsAutoVacuumLauncherProcess())
pgStatDBHash = pgstat_read_statsfile(InvalidOid);
pgStatDBHash = pgstat_read_statsfile(InvalidOid, false);
else
pgStatDBHash = pgstat_read_statsfile(MyDatabaseId);
pgStatDBHash = pgstat_read_statsfile(MyDatabaseId, false);
}

5
src/bin/initdb/initdb.c
View File

@ -42,7 +42,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
* Portions taken from FreeBSD.
*
* $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.158 2008/07/19 04:01:29 tgl Exp $
* $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.159 2008/08/05 12:09:30 mha Exp $
*
*-------------------------------------------------------------------------
*/
@ -2461,7 +2461,8 @@ main(int argc, char *argv[])
"pg_multixact/offsets",
"base",
"base/1",
"pg_tblspc"
"pg_tblspc",
"pg_stat_tmp"
};
progname = get_progname(argv[0]);

4
src/include/catalog/catversion.h
View File

@ -37,7 +37,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.474 2008/08/02 21:32:00 tgl Exp $
* $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.475 2008/08/05 12:09:30 mha Exp $
*
*-------------------------------------------------------------------------
*/
@ -53,6 +53,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 200808011
#define CATALOG_VERSION_NO 200808051
#endif