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Commit77698e1

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committed
Avoid repeated detoasting (and possible memory leaks) when processing
a toasted datum in VACUUM ANALYZE.
1 parent079c60a commit77698e1

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2 files changed

+64
-36
lines changed

2 files changed

+64
-36
lines changed

‎src/backend/commands/analyze.c

Lines changed: 47 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -8,19 +8,18 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/commands/analyze.c,v 1.9 2000/11/16 22:30:19 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/commands/analyze.c,v 1.10 2000/12/02 19:38:34 tgl Exp $
1212
*
13-
1413
*-------------------------------------------------------------------------
1514
*/
15+
#include"postgres.h"
16+
1617
#include<sys/types.h>
1718
#include<sys/file.h>
1819
#include<sys/stat.h>
1920
#include<fcntl.h>
2021
#include<unistd.h>
2122

22-
#include"postgres.h"
23-
2423
#include"access/heapam.h"
2524
#include"catalog/catname.h"
2625
#include"catalog/indexing.h"
@@ -159,7 +158,8 @@ analyze_rel(Oid relid, List *anal_cols2, int MESSAGE_LEVEL)
159158

160159
stats=&vacattrstats[i];
161160
stats->attr=palloc(ATTRIBUTE_TUPLE_SIZE);
162-
memmove(stats->attr,attr[((attnums) ?attnums[i] :i)],ATTRIBUTE_TUPLE_SIZE);
161+
memcpy(stats->attr,attr[((attnums) ?attnums[i] :i)],
162+
ATTRIBUTE_TUPLE_SIZE);
163163
stats->best=stats->guess1=stats->guess2=0;
164164
stats->max=stats->min=0;
165165
stats->best_len=stats->guess1_len=stats->guess2_len=0;
@@ -220,6 +220,7 @@ analyze_rel(Oid relid, List *anal_cols2, int MESSAGE_LEVEL)
220220
/* delete existing pg_statistic rows for relation */
221221
del_stats(relid, ((attnums) ?attr_cnt :0),attnums);
222222

223+
/* scan relation to gather statistics */
223224
scan=heap_beginscan(onerel, false,SnapshotNow,0,NULL);
224225

225226
while (HeapTupleIsValid(tuple=heap_getnext(scan,0)))
@@ -237,7 +238,7 @@ analyze_rel(Oid relid, List *anal_cols2, int MESSAGE_LEVEL)
237238
}
238239

239240
/*
240-
*attr_stats() -- compute column statistics used by theoptimzer
241+
*attr_stats() -- compute column statistics used by theplanner
241242
*
242243
*We compute the column min, max, null and non-null counts.
243244
*Plus we attempt to find the count of the value that occurs most
@@ -266,6 +267,7 @@ attr_stats(Relation onerel, int attr_cnt, VacAttrStats *vacattrstats, HeapTuple
266267
for (i=0;i<attr_cnt;i++)
267268
{
268269
VacAttrStats*stats=&vacattrstats[i];
270+
Datumorigvalue;
269271
Datumvalue;
270272
boolisnull;
271273
boolvalue_hit;
@@ -278,16 +280,25 @@ attr_stats(Relation onerel, int attr_cnt, VacAttrStats *vacattrstats, HeapTuple
278280
continue;
279281
#endif/* _DROP_COLUMN_HACK__ */
280282

281-
value=heap_getattr(tuple,
282-
stats->attr->attnum,tupDesc,&isnull);
283+
origvalue=heap_getattr(tuple,stats->attr->attnum,
284+
tupDesc,&isnull);
283285

284286
if (isnull)
285287
{
286288
stats->null_cnt++;
287289
continue;
288290
}
289-
290291
stats->nonnull_cnt++;
292+
293+
/*
294+
* If the value is toasted, detoast it to avoid repeated detoastings
295+
* and resultant memory leakage inside the comparison routines.
296+
*/
297+
if (!stats->attr->attbyval&&stats->attr->attlen==-1)
298+
value=PointerGetDatum(PG_DETOAST_DATUM(origvalue));
299+
else
300+
value=origvalue;
301+
291302
if (!stats->initialized)
292303
{
293304
bucketcpy(stats->attr,value,&stats->best,&stats->best_len);
@@ -365,22 +376,26 @@ attr_stats(Relation onerel, int attr_cnt, VacAttrStats *vacattrstats, HeapTuple
365376
stats->guess1_hits=1;
366377
stats->guess2_hits=1;
367378
}
379+
380+
/* Clean up detoasted copy, if any */
381+
if (value!=origvalue)
382+
pfree(DatumGetPointer(value));
368383
}
369384
}
370385

371386
/*
372387
*bucketcpy() -- copy a new value into one of the statistics buckets
373-
*
374388
*/
375389
staticvoid
376390
bucketcpy(Form_pg_attributeattr,Datumvalue,Datum*bucket,int*bucket_len)
377391
{
378-
if (attr->attbyval&&attr->attlen!=-1)
392+
if (attr->attbyval)
379393
*bucket=value;
380394
else
381395
{
382396
intlen= (attr->attlen!=-1 ?attr->attlen :VARSIZE(value));
383397

398+
/* Avoid unnecessary palloc() traffic... */
384399
if (len>*bucket_len)
385400
{
386401
if (*bucket_len!=0)
@@ -396,8 +411,27 @@ bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int *bucket_len)
396411
/*
397412
*update_attstats() -- update attribute statistics for one relation
398413
*
399-
*Updates of pg_attribute statistics are handled by over-write,
400-
*for reasons described above. pg_statistic rows are added normally.
414+
*Statistics are stored in several places: the pg_class row for the
415+
*relation has stats about the whole relation, the pg_attribute rows
416+
*for each attribute store "dispersion", and there is a pg_statistic
417+
*row for each (non-system) attribute. (Dispersion probably ought to
418+
*be moved to pg_statistic, but it's not worth doing unless there's
419+
*another reason to have to change pg_attribute.) The pg_class values
420+
*are updated by VACUUM, not here.
421+
*
422+
*We violate no-overwrite semantics here by storing new values for
423+
*the dispersion column directly into the pg_attribute tuple that's
424+
*already on the page. The reason for this is that if we updated
425+
*these tuples in the usual way, vacuuming pg_attribute itself
426+
*wouldn't work very well --- by the time we got done with a vacuum
427+
*cycle, most of the tuples in pg_attribute would've been obsoleted.
428+
*Updating pg_attribute's own statistics would be especially tricky.
429+
*Of course, this only works for fixed-size never-null columns, but
430+
*dispersion is.
431+
*
432+
*pg_statistic rows are just added normally. This means that
433+
*pg_statistic will probably contain some deleted rows at the
434+
*completion of a vacuum cycle, unless it happens to get vacuumed last.
401435
*
402436
*To keep things simple, we punt for pg_statistic, and don't try
403437
*to compute or store rows for pg_statistic itself in pg_statistic.

‎src/backend/commands/vacuum.c

Lines changed: 17 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -8,21 +8,28 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.174 2000/11/30 08:46:22 vadim Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.175 2000/12/02 19:38:34 tgl Exp $
1212
*
13-
1413
*-------------------------------------------------------------------------
1514
*/
15+
#include"postgres.h"
16+
1617
#include<sys/types.h>
1718
#include<sys/file.h>
1819
#include<sys/stat.h>
1920
#include<fcntl.h>
2021
#include<unistd.h>
2122

22-
#include"postgres.h"
23+
#ifndefHAVE_GETRUSAGE
24+
#include"rusagestub.h"
25+
#else
26+
#include<sys/time.h>
27+
#include<sys/resource.h>
28+
#endif
2329

2430
#include"access/genam.h"
2531
#include"access/heapam.h"
32+
#include"access/xlog.h"
2633
#include"catalog/catalog.h"
2734
#include"catalog/catname.h"
2835
#include"catalog/index.h"
@@ -40,14 +47,6 @@
4047
#include"utils/syscache.h"
4148
#include"utils/temprel.h"
4249

43-
#ifndefHAVE_GETRUSAGE
44-
#include"rusagestub.h"
45-
#else
46-
#include<sys/time.h>
47-
#include<sys/resource.h>
48-
#endif
49-
50-
#include"access/xlog.h"
5150
externXLogRecPtrlog_heap_move(Relationreln,
5251
ItemPointerDatafrom,HeapTuplenewtup);
5352

@@ -62,7 +61,7 @@ static void vacuum_init(void);
6261
staticvoidvacuum_shutdown(void);
6362
staticvoidvac_vacuum(NameData*VacRelP,boolanalyze,List*anal_cols2);
6463
staticVRelListgetrels(NameData*VacRelP);
65-
staticvoidvacuum_rel(Oidrelid,boolanalyze,boolis_toastrel);
64+
staticvoidvacuum_rel(Oidrelid,boolis_toastrel);
6665
staticvoidscan_heap(VRelStats*vacrelstats,Relationonerel,VacPageListvacuum_pages,VacPageListfraged_pages);
6766
staticvoidrepair_frag(VRelStats*vacrelstats,Relationonerel,VacPageListvacuum_pages,VacPageListfraged_pages,intnindices,Relation*Irel);
6867
staticvoidvacuum_heap(VRelStats*vacrelstats,Relationonerel,VacPageListvacpagelist);
@@ -240,7 +239,7 @@ vac_vacuum(NameData *VacRelP, bool analyze, List *anal_cols2)
240239
/* vacuum each heap relation */
241240
for (cur=vrl;cur!= (VRelList)NULL;cur=cur->vrl_next)
242241
{
243-
vacuum_rel(cur->vrl_relid,analyze,false);
242+
vacuum_rel(cur->vrl_relid, false);
244243
/* analyze separately so locking is minimized */
245244
if (analyze)
246245
analyze_rel(cur->vrl_relid,anal_cols2,MESSAGE_LEVEL);
@@ -352,7 +351,7 @@ getrels(NameData *VacRelP)
352351
*us to lock the entire database during one pass of the vacuum cleaner.
353352
*/
354353
staticvoid
355-
vacuum_rel(Oidrelid,boolanalyze,boolis_toastrel)
354+
vacuum_rel(Oidrelid,boolis_toastrel)
356355
{
357356
Relationonerel;
358357
VacPageListDatavacuum_pages;/* List of pages to vacuum and/or clean
@@ -532,7 +531,7 @@ vacuum_rel(Oid relid, bool analyze, bool is_toastrel)
532531
* totally unimportant for toast relations
533532
*/
534533
if (toast_relid!=InvalidOid)
535-
vacuum_rel(toast_relid,false,true);
534+
vacuum_rel(toast_relid, true);
536535

537536
/* next command frees attribute stats */
538537
if (!is_toastrel)
@@ -2187,14 +2186,9 @@ tid_reaped(ItemPointer itemptr, VacPageList vacpagelist)
21872186
/*
21882187
*update_relstats() -- update statistics for one relation
21892188
*
2190-
*Statistics are stored in several places: the pg_class row for the
2191-
*relation has stats about the whole relation, the pg_attribute rows
2192-
*for each attribute store "dispersion", and there is a pg_statistic
2193-
*row for each (non-system) attribute. (Dispersion probably ought to
2194-
*be moved to pg_statistic, but it's not worth doing unless there's
2195-
*another reason to have to change pg_attribute.) Dispersion and
2196-
*pg_statistic values are only updated by VACUUM ANALYZE, but we
2197-
*always update the stats in pg_class.
2189+
*Update the whole-relation statistics that are kept in its pg_class
2190+
*row. There are additional stats that will be updated if we are
2191+
*doing VACUUM ANALYZE, but we always update these stats.
21982192
*
21992193
*This routine works for both index and heap relation entries in
22002194
*pg_class. We violate no-overwrite semantics here by storing new

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