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Commit87d95ca

Browse files
committed
Arrange for VACUUM to delete the init file that relcache.c uses
to save a little bit of backend startup time. This way, the firstbackend started after a VACUUM will rebuild the init file with up-to-datestatistics for the critical system indexes.
1 parentf7d25d2 commit87d95ca

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3 files changed

+41
-20
lines changed

3 files changed

+41
-20
lines changed

‎src/backend/commands/vacuum.c‎

Lines changed: 16 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.99 1999/04/12 16:56:36 vadim Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.100 1999/05/01 19:09:46 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -46,6 +46,7 @@
4646
#include"utils/inval.h"
4747
#include"utils/mcxt.h"
4848
#include"utils/portal.h"
49+
#include"utils/relcache.h"
4950
#include"utils/syscache.h"
5051

5152
#ifndefHAVE_GETRUSAGE
@@ -219,7 +220,20 @@ vc_init()
219220
staticvoid
220221
vc_shutdown()
221222
{
222-
/* on entry, not in a transaction */
223+
/* on entry, we are not in a transaction */
224+
225+
/* Flush the init file that relcache.c uses to save startup time.
226+
* The next backend startup will rebuild the init file with up-to-date
227+
* information from pg_class. This lets the optimizer see the stats that
228+
* we've collected for certain critical system indexes. See relcache.c
229+
* for more details.
230+
*
231+
* Ignore any failure to unlink the file, since it might not be there
232+
* if no backend has been started since the last vacuum...
233+
*/
234+
unlink(RELCACHE_INIT_FILENAME);
235+
236+
/* remove the vacuum cleaner lock file */
223237
if (unlink("pg_vlock")<0)
224238
elog(ERROR,"vacuum: can't destroy lock file!");
225239

‎src/backend/utils/cache/relcache.c‎

Lines changed: 18 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.59 1999/02/21 03:49:36 scrappy Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.60 1999/05/01 19:09:44 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -77,7 +77,6 @@
7777
#include"utils/memutils.h"
7878
#include"utils/rel.h"
7979
#include"utils/relcache.h"
80-
#include"utils/relcache.h"
8180
#include"utils/syscache.h"
8281

8382

@@ -87,13 +86,6 @@ static Relation RelationNameCacheGetRelation(char *relationName);
8786
staticvoidinit_irels(void);
8887
staticvoidwrite_irels(void);
8988

90-
/* ----------------
91-
*defines
92-
* ----------------
93-
*/
94-
#defineprivate static
95-
#defineINIT_FILENAME"pg_internal.init"
96-
9789
/* ----------------
9890
*externs
9991
* ----------------
@@ -1826,11 +1818,20 @@ RelCheckFetch(Relation relation)
18261818
* from an initialization file in the data/base/... directory.
18271819
*
18281820
* + If the initialization file isn't there, then we create the
1829-
* relationdescriptor using sequential scans and writeit to
1821+
* relationdescriptors using sequential scans and write'em to
18301822
* the initialization file for use by subsequent backends.
18311823
*
1832-
*This is complicated and interferes with system changes, but
1833-
*performance is so bad that we're willing to pay the tax.
1824+
*We could dispense with the initialization file and just build the
1825+
*critical reldescs the hard way on every backend startup, but that
1826+
*slows down backend startup noticeably if pg_class is large.
1827+
*
1828+
*As of v6.5, vacuum.c deletes the initialization file at completion
1829+
*of a VACUUM, so that it will be rebuilt at the next backend startup.
1830+
*This ensures that vacuum-collected stats for the system indexes
1831+
*will eventually get used by the optimizer --- otherwise the relcache
1832+
*entries for these indexes will show zero sizes forever, since the
1833+
*relcache entries are pinned in memory and will never be reloaded
1834+
*from pg_class.
18341835
*/
18351836

18361837
/* pg_attnumind, pg_classnameind, pg_classoidind */
@@ -1852,9 +1853,9 @@ init_irels(void)
18521853
intrelno;
18531854

18541855
#ifndef__CYGWIN32__
1855-
if ((fd=FileNameOpenFile(INIT_FILENAME,O_RDONLY,0600))<0)
1856+
if ((fd=FileNameOpenFile(RELCACHE_INIT_FILENAME,O_RDONLY,0600))<0)
18561857
#else
1857-
if ((fd=FileNameOpenFile(INIT_FILENAME,O_RDONLY |O_BINARY,0600))<0)
1858+
if ((fd=FileNameOpenFile(RELCACHE_INIT_FILENAME,O_RDONLY |O_BINARY,0600))<0)
18581859
#endif
18591860
{
18601861
write_irels();
@@ -2017,12 +2018,12 @@ write_irels(void)
20172018
RelationBuildDescInfobi;
20182019

20192020
#ifndef__CYGWIN32__
2020-
fd=FileNameOpenFile(INIT_FILENAME,O_WRONLY |O_CREAT |O_TRUNC,0600);
2021+
fd=FileNameOpenFile(RELCACHE_INIT_FILENAME,O_WRONLY |O_CREAT |O_TRUNC,0600);
20212022
#else
2022-
fd=FileNameOpenFile(INIT_FILENAME,O_WRONLY |O_CREAT |O_TRUNC |O_BINARY,0600);
2023+
fd=FileNameOpenFile(RELCACHE_INIT_FILENAME,O_WRONLY |O_CREAT |O_TRUNC |O_BINARY,0600);
20232024
#endif
20242025
if (fd<0)
2025-
elog(FATAL,"cannot create init file %s",INIT_FILENAME);
2026+
elog(FATAL,"cannot create init file %s",RELCACHE_INIT_FILENAME);
20262027

20272028
FileSeek(fd,0L,SEEK_SET);
20282029

‎src/include/utils/relcache.h‎

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
*
77
* Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: relcache.h,v 1.11 1999/02/13 23:22:31 momjian Exp $
9+
* $Id: relcache.h,v 1.12 1999/05/01 19:09:43 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -34,4 +34,10 @@ extern void RelationRegisterRelation(Relation relation);
3434
externvoidRelationPurgeLocalRelation(boolxactComitted);
3535
externvoidRelationInitialize(void);
3636

37+
/*
38+
* both vacuum.c and relcache.c need to know the name of the relcache init file
39+
*/
40+
41+
#defineRELCACHE_INIT_FILENAME"pg_internal.init"
42+
3743
#endif/* RELCACHE_H */

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