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

author Magnus Hagander <magnus@hagander.net>

Tue, 5 Aug 2008 12:09:30 +0000 (12:09 +0000)

committer Magnus Hagander <magnus@hagander.net>

Tue, 5 Aug 2008 12:09:30 +0000 (12:09 +0000)

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.

doc/src/sgml/monitoring.sgml patch | blob | blame | history

doc/src/sgml/storage.sgml patch | blob | blame | history

src/backend/postmaster/pgstat.c patch | blob | blame | history

src/bin/initdb/initdb.c patch | blob | blame | history

src/include/catalog/catversion.h patch | blob | blame | history

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml

index 0d56e39d6f470a1dd59003a463676f879696a351..29a3e1070304eebf3cec41993d4d4714b55e7a10 100644 (file)

--- a/doc/src/sgml/monitoring.sgml

+++ b/doc/src/sgml/monitoring.sgml

@@ -1,4 +1,4 @@

-

+

<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>

diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml

index 0303a2b3d4e5854d82bfb39320c88c5b04aa0271..e564fd2be9a06bf8963adfd86425109c8ca48a76 100644 (file)

--- a/doc/src/sgml/storage.sgml

+++ b/doc/src/sgml/storage.sgml

@@ -1,4 +1,4 @@

-

+

@@ -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>

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c

index d0e190aa44a6c6c8d3ec3fe92e3d2625c073ab77..f78e8840b2f39f9d901ceed94a685cd69e6845dc 100644 (file)

--- a/src/backend/postmaster/pgstat.c

+++ b/src/backend/postmaster/pgstat.c

@@ -13,7 +13,7 @@

- * $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.177 2008年08月01日 13:16:08 alvherre Exp $

+ * $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.178 2008年08月05日 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);

}

diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c

index a7ef3c9227dd7dc9b9287e19919c991a2ee37a43..e305c69fa3c47bd01be892c9823561554dece264 100644 (file)

--- a/src/bin/initdb/initdb.c

+++ b/src/bin/initdb/initdb.c

@@ -42,7 +42,7 @@

* Portions taken from FreeBSD.

- * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.158 2008年07月19日 04:01:29 tgl Exp $

+ * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.159 2008年08月05日 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]);

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h

index 49d2a32431db929f0559b24a87f3779dfb41ee76..6be25b05f979444a6e9dcc0f2164630914044d2a 100644 (file)

--- a/src/include/catalog/catversion.h

+++ b/src/include/catalog/catversion.h

@@ -37,7 +37,7 @@

- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.474 2008年08月02日 21:32:00 tgl Exp $

+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.475 2008年08月05日 12:09:30 mha Exp $

*-------------------------------------------------------------------------

@@ -53,6 +53,6 @@

/* yyyymmddN */

-#define CATALOG_VERSION_NO 200808011

+#define CATALOG_VERSION_NO 200808051

#endif

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