Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit9513918

Browse files
committed
Fix up flushing of composite-type typcache entries to be driven directly by
SI invalidation events, rather than indirectly through the relcache.In the previous coding, we had to flush a composite-type typcache entrywhenever we discarded the corresponding relcache entry. This caused problemsat least when testing with RELCACHE_FORCE_RELEASE, as shown in recent reportfrom Jeff Davis, and might result in real-world problems given the kind ofunexpected relcache flush that that test mechanism is intended to model.The new coding decouples relcache and typcache management, which is a goodthing anyway from a structural perspective. The cost is that we have tosearch the typcache linearly to find entries that need to be flushed. Thereare a couple of ways we could avoid that, but at the moment it's not clearit's worth any extra trouble, because the typcache contains very few entriesin typical operation.Back-patch to 8.2, the same as some other recent fixes in this general area.The patch could be carried back to 8.0 with some additional work, but giventhat it's only hypothetical whether we're fixing any problem observable inthe field, it doesn't seem worth the work now.
1 parentf3c903f commit9513918

File tree

3 files changed

+53
-43
lines changed

3 files changed

+53
-43
lines changed

‎src/backend/utils/cache/relcache.c

Lines changed: 1 addition & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.312 2010/08/13 20:10:52 rhaas Exp $
11+
* $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.313 2010/09/02 03:16:45 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -77,7 +77,6 @@
7777
#include"utils/resowner.h"
7878
#include"utils/syscache.h"
7979
#include"utils/tqual.h"
80-
#include"utils/typcache.h"
8180

8281

8382
/*
@@ -1854,8 +1853,6 @@ RelationDestroyRelation(Relation relation)
18541853
staticvoid
18551854
RelationClearRelation(Relationrelation,boolrebuild)
18561855
{
1857-
Oidold_reltype=relation->rd_rel->reltype;
1858-
18591856
/*
18601857
* As per notes above, a rel to be rebuilt MUST have refcnt > 0; while of
18611858
* course it would be a bad idea to blow away one with nonzero refcnt.
@@ -1925,9 +1922,6 @@ RelationClearRelation(Relation relation, bool rebuild)
19251922
*/
19261923
if (!rebuild)
19271924
{
1928-
/* Flush any rowtype cache entry */
1929-
flush_rowtype_cache(old_reltype);
1930-
19311925
/* Remove it from the hash table */
19321926
RelationCacheDelete(relation);
19331927

@@ -1975,16 +1969,13 @@ RelationClearRelation(Relation relation, bool rebuild)
19751969
if (newrel==NULL)
19761970
{
19771971
/* Should only get here if relation was deleted */
1978-
flush_rowtype_cache(old_reltype);
19791972
RelationCacheDelete(relation);
19801973
RelationDestroyRelation(relation);
19811974
elog(ERROR,"relation %u deleted while still in use",save_relid);
19821975
}
19831976

19841977
keep_tupdesc=equalTupleDescs(relation->rd_att,newrel->rd_att);
19851978
keep_rules=equalRuleLocks(relation->rd_rules,newrel->rd_rules);
1986-
if (!keep_tupdesc)
1987-
flush_rowtype_cache(old_reltype);
19881979

19891980
/*
19901981
* Perform swapping of the relcache entry contents. Within this

‎src/backend/utils/cache/typcache.c

Lines changed: 51 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -4,14 +4,14 @@
44
* POSTGRES type cache code
55
*
66
* The type cache exists to speed lookup of certain information about data
7-
* types that is not directly available from a type's pg_type row.In
8-
*particular, we use a type's default btree opclass, or the default hash
7+
* types that is not directly available from a type's pg_type row.For
8+
*example, we use a type's default btree opclass, or the default hash
99
* opclass if no btree opclass exists, to determine which operators should
1010
* be used for grouping and sorting the type (GROUP BY, ORDER BY ASC/DESC).
1111
*
1212
* Several seemingly-odd choices have been made to support use of the type
1313
* cache by the generic array comparison routines array_eq() and array_cmp().
14-
* Becausethese routines are used as index support operations, they cannot
14+
* Becausethose routines are used as index support operations, they cannot
1515
* leak memory. To allow them to execute efficiently, all information that
1616
* either of them would like to re-use across calls is made available in the
1717
* type cache.
@@ -36,7 +36,7 @@
3636
* Portions Copyright (c) 1994, Regents of the University of California
3737
*
3838
* IDENTIFICATION
39-
* $PostgreSQL: pgsql/src/backend/utils/cache/typcache.c,v 1.32 2010/02/14 18:42:17 rhaas Exp $
39+
* $PostgreSQL: pgsql/src/backend/utils/cache/typcache.c,v 1.33 2010/09/02 03:16:46 tgl Exp $
4040
*
4141
*-------------------------------------------------------------------------
4242
*/
@@ -48,6 +48,7 @@
4848
#include"catalog/pg_type.h"
4949
#include"commands/defrem.h"
5050
#include"utils/builtins.h"
51+
#include"utils/inval.h"
5152
#include"utils/lsyscache.h"
5253
#include"utils/rel.h"
5354
#include"utils/syscache.h"
@@ -86,6 +87,8 @@ static TupleDesc *RecordCacheArray = NULL;
8687
staticint32RecordCacheArrayLen=0;/* allocated length of array */
8788
staticint32NextRecordTypmod=0;/* number of entries used */
8889

90+
staticvoidTypeCacheRelCallback(Datumarg,Oidrelid);
91+
8992

9093
/*
9194
* lookup_type_cache
@@ -116,6 +119,9 @@ lookup_type_cache(Oid type_id, int flags)
116119
TypeCacheHash=hash_create("Type information cache",64,
117120
&ctl,HASH_ELEM |HASH_FUNCTION);
118121

122+
/* Also set up a callback for relcache SI invalidations */
123+
CacheRegisterRelcacheCallback(TypeCacheRelCallback, (Datum)0);
124+
119125
/* Also make sure CacheMemoryContext exists */
120126
if (!CacheMemoryContext)
121127
CreateCacheMemoryContext();
@@ -497,36 +503,51 @@ assign_record_type_typmod(TupleDesc tupDesc)
497503
}
498504

499505
/*
500-
* flush_rowtype_cache
506+
* TypeCacheRelCallback
507+
*Relcache inval callback function
508+
*
509+
* Delete the cached tuple descriptor (if any) for the given rel's composite
510+
* type, or for all composite types if relid == InvalidOid.
501511
*
502-
* If a typcache entry exists for a rowtype, delete the entry's cached
503-
* tuple descriptor link. This is called from relcache.c when a cached
504-
* relation tupdesc is about to be dropped.
512+
* This is called when a relcache invalidation event occurs for the given
513+
* relid. We must scan the whole typcache hash since we don't know the
514+
* type OID corresponding to the relid. We could do a direct search if this
515+
* were a syscache-flush callback on pg_type, but then we would need all
516+
* ALTER-TABLE-like commands that could modify a rowtype to issue syscache
517+
* invals against the rel's pg_type OID. The extra SI signaling could very
518+
* well cost more than we'd save, since in most usages there are not very
519+
* many entries in a backend's typcache. The risk of bugs-of-omission seems
520+
* high, too.
521+
*
522+
* Another possibility, with only localized impact, is to maintain a second
523+
* hashtable that indexes composite-type typcache entries by their typrelid.
524+
* But it's still not clear it's worth the trouble.
505525
*/
506-
void
507-
flush_rowtype_cache(Oidtype_id)
526+
staticvoid
527+
TypeCacheRelCallback(Datumarg,Oidrelid)
508528
{
529+
HASH_SEQ_STATUSstatus;
509530
TypeCacheEntry*typentry;
510531

511-
if (TypeCacheHash==NULL)
512-
return;/* no table, so certainly no entry */
513-
514-
typentry= (TypeCacheEntry*)hash_search(TypeCacheHash,
515-
(void*)&type_id,
516-
HASH_FIND,NULL);
517-
if (typentry==NULL)
518-
return;/* no matching entry */
519-
if (typentry->tupDesc==NULL)
520-
return;/* tupdesc hasn't been requested */
521-
522-
/*
523-
* Release our refcount and free the tupdesc if none remain. (Can't use
524-
* DecrTupleDescRefCount because this reference is not logged in current
525-
* resource owner.)
526-
*/
527-
Assert(typentry->tupDesc->tdrefcount>0);
528-
if (--typentry->tupDesc->tdrefcount==0)
529-
FreeTupleDesc(typentry->tupDesc);
532+
/* TypeCacheHash must exist, else this callback wouldn't be registered */
533+
hash_seq_init(&status,TypeCacheHash);
534+
while ((typentry= (TypeCacheEntry*)hash_seq_search(&status))!=NULL)
535+
{
536+
if (typentry->tupDesc==NULL)
537+
continue;/* not composite, or tupdesc hasn't been requested */
530538

531-
typentry->tupDesc=NULL;
539+
/* Delete if match, or if we're zapping all composite types */
540+
if (relid==typentry->typrelid||relid==InvalidOid)
541+
{
542+
/*
543+
* Release our refcount, and free the tupdesc if none remain.
544+
* (Can't use DecrTupleDescRefCount because this reference is not
545+
* logged in current resource owner.)
546+
*/
547+
Assert(typentry->tupDesc->tdrefcount>0);
548+
if (--typentry->tupDesc->tdrefcount==0)
549+
FreeTupleDesc(typentry->tupDesc);
550+
typentry->tupDesc=NULL;
551+
}
552+
}
532553
}

‎src/include/utils/typcache.h

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
1010
* Portions Copyright (c) 1994, Regents of the University of California
1111
*
12-
* $PostgreSQL: pgsql/src/include/utils/typcache.h,v 1.18 2010/01/02 16:58:10 momjian Exp $
12+
* $PostgreSQL: pgsql/src/include/utils/typcache.h,v 1.19 2010/09/0203:16:46 tgl Exp $
1313
*
1414
*-------------------------------------------------------------------------
1515
*/
@@ -86,6 +86,4 @@ extern TupleDesc lookup_rowtype_tupdesc_copy(Oid type_id, int32 typmod);
8686

8787
externvoidassign_record_type_typmod(TupleDesctupDesc);
8888

89-
externvoidflush_rowtype_cache(Oidtype_id);
90-
9189
#endif/* TYPCACHE_H */

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp