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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
parent
7e61edf2e7
commit
70d756970b
@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.60 2008/06/18 17:44:12 neilc Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.61 2008/08/05 12:09:30 mha Exp $ -->
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<chapter id="monitoring">
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<title>Monitoring Database Activity</title>
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@ -164,6 +164,17 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
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only superusers are allowed to change these parameters with
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<command>SET</>.)
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</para>
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<para>
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The statistics collector communicates with the backends needing
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information (including autovacuum) through temporary files.
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These files are stored in the <filename>pg_stat_tmp</filename> subdirectory.
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When the postmaster shuts down, a permanent copy of the statistics
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data is stored in the <filename>global</filename> subdirectory. For increased
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performance, it is possible to mount or symlink a RAM based
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filesystem to the <filename>pg_stat_tmp</filename> directory.
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</para>
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</sect2>
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<sect2 id="monitoring-stats-views">
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@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.23 2008/05/02 01:08:26 tgl Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.24 2008/08/05 12:09:30 mha Exp $ -->
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<chapter id="storage">
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@ -77,6 +77,12 @@ Item
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(used for shared row locks)</entry>
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</row>
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<row>
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<entry><filename>pg_stat_tmp</></entry>
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<entry>Subdirectory containing temporary files for the statistics
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subsystem</entry>
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</row>
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<row>
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<entry><filename>pg_subtrans</></entry>
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<entry>Subdirectory containing subtransaction status data</entry>
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@ -13,7 +13,7 @@
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*
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* Copyright (c) 2001-2008, PostgreSQL Global Development Group
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*
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* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.177 2008/08/01 13:16:08 alvherre Exp $
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* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.178 2008/08/05 12:09:30 mha Exp $
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* ----------
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*/
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#include "postgres.h"
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@ -68,8 +68,10 @@
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* Paths for the statistics files (relative to installation's $PGDATA).
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* ----------
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*/
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#define PGSTAT_STAT_FILENAME "global/pgstat.stat"
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#define PGSTAT_STAT_TMPFILE "global/pgstat.tmp"
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#define PGSTAT_STAT_PERMANENT_FILENAME "global/pgstat.stat"
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#define PGSTAT_STAT_PERMANENT_TMPFILE "global/pgstat.tmp"
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#define PGSTAT_STAT_FILENAME "pg_stat_tmp/pgstat.stat"
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#define PGSTAT_STAT_TMPFILE "pg_stat_tmp/pgstat.tmp"
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/* ----------
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* Timer definitions.
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@ -219,8 +221,8 @@ static void force_statwrite(SIGNAL_ARGS);
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static void pgstat_beshutdown_hook(int code, Datum arg);
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static PgStat_StatDBEntry *pgstat_get_db_entry(Oid databaseid, bool create);
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static void pgstat_write_statsfile(void);
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static HTAB *pgstat_read_statsfile(Oid onlydb);
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static void pgstat_write_statsfile(bool permanent);
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static HTAB *pgstat_read_statsfile(Oid onlydb, bool permanent);
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static void backend_read_statsfile(void);
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static void pgstat_read_current_status(void);
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@ -510,6 +512,7 @@ void
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pgstat_reset_all(void)
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{
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unlink(PGSTAT_STAT_FILENAME);
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unlink(PGSTAT_STAT_PERMANENT_FILENAME);
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}
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#ifdef EXEC_BACKEND
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@ -2598,7 +2601,7 @@ PgstatCollectorMain(int argc, char *argv[])
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* zero.
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*/
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pgStatRunningInCollector = true;
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pgStatDBHash = pgstat_read_statsfile(InvalidOid);
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pgStatDBHash = pgstat_read_statsfile(InvalidOid, true);
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/*
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* Setup the descriptor set for select(2). Since only one bit in the set
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@ -2638,7 +2641,7 @@ PgstatCollectorMain(int argc, char *argv[])
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if (!PostmasterIsAlive(true))
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break;
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pgstat_write_statsfile();
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pgstat_write_statsfile(false);
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need_statwrite = false;
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need_timer = true;
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}
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@ -2806,7 +2809,7 @@ PgstatCollectorMain(int argc, char *argv[])
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/*
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* Save the final stats to reuse at next startup.
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*/
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pgstat_write_statsfile();
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pgstat_write_statsfile(true);
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exit(0);
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}
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@ -2891,10 +2894,14 @@ pgstat_get_db_entry(Oid databaseid, bool create)
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* pgstat_write_statsfile() -
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*
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* Tell the news.
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* If writing to the permanent file (happens when the collector is
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* shutting down only), remove the temporary file so that backends
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* starting up under a new postmaster can't read the old data before
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* the new collector is ready.
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* ----------
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*/
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static void
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pgstat_write_statsfile(void)
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pgstat_write_statsfile(bool permanent)
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{
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HASH_SEQ_STATUS hstat;
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HASH_SEQ_STATUS tstat;
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@ -2904,17 +2911,19 @@ pgstat_write_statsfile(void)
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PgStat_StatFuncEntry *funcentry;
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FILE *fpout;
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int32 format_id;
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const char *tmpfile = permanent?PGSTAT_STAT_PERMANENT_TMPFILE:PGSTAT_STAT_TMPFILE;
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const char *statfile = permanent?PGSTAT_STAT_PERMANENT_FILENAME:PGSTAT_STAT_FILENAME;
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/*
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* Open the statistics temp file to write out the current values.
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*/
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fpout = fopen(PGSTAT_STAT_TMPFILE, PG_BINARY_W);
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fpout = fopen(tmpfile, PG_BINARY_W);
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if (fpout == NULL)
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{
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ereport(LOG,
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(errcode_for_file_access(),
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errmsg("could not open temporary statistics file \"%s\": %m",
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PGSTAT_STAT_TMPFILE)));
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tmpfile)));
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return;
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}
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@ -2981,26 +2990,29 @@ pgstat_write_statsfile(void)
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ereport(LOG,
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(errcode_for_file_access(),
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errmsg("could not write temporary statistics file \"%s\": %m",
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PGSTAT_STAT_TMPFILE)));
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tmpfile)));
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fclose(fpout);
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unlink(PGSTAT_STAT_TMPFILE);
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unlink(tmpfile);
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}
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else if (fclose(fpout) < 0)
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{
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ereport(LOG,
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(errcode_for_file_access(),
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errmsg("could not close temporary statistics file \"%s\": %m",
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PGSTAT_STAT_TMPFILE)));
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unlink(PGSTAT_STAT_TMPFILE);
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tmpfile)));
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unlink(tmpfile);
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}
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else if (rename(PGSTAT_STAT_TMPFILE, PGSTAT_STAT_FILENAME) < 0)
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else if (rename(tmpfile, statfile) < 0)
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{
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ereport(LOG,
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(errcode_for_file_access(),
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errmsg("could not rename temporary statistics file \"%s\" to \"%s\": %m",
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PGSTAT_STAT_TMPFILE, PGSTAT_STAT_FILENAME)));
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unlink(PGSTAT_STAT_TMPFILE);
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tmpfile, statfile)));
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unlink(tmpfile);
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}
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if (permanent)
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unlink(PGSTAT_STAT_FILENAME);
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}
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@ -3012,7 +3024,7 @@ pgstat_write_statsfile(void)
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* ----------
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*/
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static HTAB *
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pgstat_read_statsfile(Oid onlydb)
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pgstat_read_statsfile(Oid onlydb, bool permanent)
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{
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PgStat_StatDBEntry *dbentry;
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PgStat_StatDBEntry dbbuf;
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@ -3027,6 +3039,7 @@ pgstat_read_statsfile(Oid onlydb)
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FILE *fpin;
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int32 format_id;
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bool found;
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const char *statfile = permanent?PGSTAT_STAT_PERMANENT_FILENAME:PGSTAT_STAT_FILENAME;
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/*
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* The tables will live in pgStatLocalContext.
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@ -3055,7 +3068,7 @@ pgstat_read_statsfile(Oid onlydb)
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* return zero for anything and the collector simply starts from scratch
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* with empty counters.
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*/
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if ((fpin = AllocateFile(PGSTAT_STAT_FILENAME, PG_BINARY_R)) == NULL)
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if ((fpin = AllocateFile(statfile, PG_BINARY_R)) == NULL)
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return dbhash;
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/*
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@ -3244,6 +3257,9 @@ pgstat_read_statsfile(Oid onlydb)
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done:
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FreeFile(fpin);
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if (permanent)
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unlink(PGSTAT_STAT_PERMANENT_FILENAME);
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return dbhash;
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}
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@ -3262,9 +3278,9 @@ backend_read_statsfile(void)
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/* Autovacuum launcher wants stats about all databases */
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if (IsAutoVacuumLauncherProcess())
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pgStatDBHash = pgstat_read_statsfile(InvalidOid);
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pgStatDBHash = pgstat_read_statsfile(InvalidOid, false);
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else
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pgStatDBHash = pgstat_read_statsfile(MyDatabaseId);
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pgStatDBHash = pgstat_read_statsfile(MyDatabaseId, false);
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}
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@ -42,7 +42,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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* Portions taken from FreeBSD.
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*
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* $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.158 2008/07/19 04:01:29 tgl Exp $
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* $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.159 2008/08/05 12:09:30 mha Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -2461,7 +2461,8 @@ main(int argc, char *argv[])
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"pg_multixact/offsets",
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"base",
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"base/1",
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"pg_tblspc"
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"pg_tblspc",
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"pg_stat_tmp"
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};
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progname = get_progname(argv[0]);
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@ -37,7 +37,7 @@
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* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.474 2008/08/02 21:32:00 tgl Exp $
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* $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.475 2008/08/05 12:09:30 mha Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -53,6 +53,6 @@
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*/
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/* yyyymmddN */
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#define CATALOG_VERSION_NO 200808011
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#define CATALOG_VERSION_NO 200808051
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#endif
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