@ -4,14 +4,14 @@
* POSTGRES type cache code
*
* The type cache exists to speed lookup of certain information about data
* types that is not directly available from a type ' s pg_type row . In
* particular , we use a type ' s default btree opclass , or the default hash
* types that is not directly available from a type ' s pg_type row . For
* example , we use a type ' s default btree opclass , or the default hash
* opclass if no btree opclass exists , to determine which operators should
* be used for grouping and sorting the type ( GROUP BY , ORDER BY ASC / DESC ) .
*
* Several seemingly - odd choices have been made to support use of the type
* cache by the generic array comparison routines array_eq ( ) and array_cmp ( ) .
* Because the se routines are used as index support operations , they cannot
* Because tho se routines are used as index support operations , they cannot
* leak memory . To allow them to execute efficiently , all information that
* either of them would like to re - use across calls is made available in the
* type cache .
@ -36,7 +36,7 @@
* Portions Copyright ( c ) 1994 , Regents of the University of California
*
* IDENTIFICATION
* $ PostgreSQL : pgsql / src / backend / utils / cache / typcache . c , v 1.29 2009 / 01 / 01 17 : 23 : 50 momjian Exp $
* $ PostgreSQL : pgsql / src / backend / utils / cache / typcache . c , v 1.29 .2 .1 2010 / 09 / 02 03 : 16 : 59 tgl Exp $
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
@ -48,6 +48,7 @@
# include "catalog/pg_type.h"
# include "commands/defrem.h"
# include "utils/builtins.h"
# include "utils/inval.h"
# include "utils/lsyscache.h"
# include "utils/rel.h"
# include "utils/syscache.h"
@ -86,6 +87,8 @@ static TupleDesc *RecordCacheArray = NULL;
static int32 RecordCacheArrayLen = 0 ; /* allocated length of array */
static int32 NextRecordTypmod = 0 ; /* number of entries used */
static void TypeCacheRelCallback ( Datum arg , Oid relid ) ;
/*
* lookup_type_cache
@ -118,6 +121,9 @@ lookup_type_cache(Oid type_id, int flags)
ctl . hash = oid_hash ;
TypeCacheHash = hash_create ( " Type information cache " , 64 ,
& ctl , HASH_ELEM | HASH_FUNCTION ) ;
/* Also set up a callback for relcache SI invalidations */
CacheRegisterRelcacheCallback ( TypeCacheRelCallback , ( Datum ) 0 ) ;
}
/* Try to look up an existing entry */
@ -497,36 +503,51 @@ assign_record_type_typmod(TupleDesc tupDesc)
}
/*
* flush_rowtype_cache
* TypeCacheRelCallback
* Relcache inval callback function
*
* Delete the cached tuple descriptor ( if any ) for the given rel ' s composite
* type , or for all composite types if relid = = InvalidOid .
*
* If a typcache entry exists for a rowtype , delete the entry ' s cached
* tuple descriptor link . This is called from relcache . c when a cached
* relation tupdesc is about to be dropped .
* This is called when a relcache invalidation event occurs for the given
* relid . We must scan the whole typcache hash since we don ' t know the
* type OID corresponding to the relid . We could do a direct search if this
* were a syscache - flush callback on pg_type , but then we would need all
* ALTER - TABLE - like commands that could modify a rowtype to issue syscache
* invals against the rel ' s pg_type OID . The extra SI signaling could very
* well cost more than we ' d save , since in most usages there are not very
* many entries in a backend ' s typcache . The risk of bugs - of - omission seems
* high , too .
*
* Another possibility , with only localized impact , is to maintain a second
* hashtable that indexes composite - type typcache entries by their typrelid .
* But it ' s still not clear it ' s worth the trouble .
*/
void
flush_rowtype_cache ( Oid type_id )
static void
TypeCacheRelCallback ( Datum arg , Oid rel id)
{
HASH_SEQ_STATUS status ;
TypeCacheEntry * typentry ;
if ( TypeCacheHash = = NULL )
return ; /* no table, so certainly no entry */
typentry = ( TypeCacheEntry * ) hash_search ( TypeCacheHash ,
( void * ) & type_id ,
HASH_FIND , NULL ) ;
if ( typentry = = NULL )
return ; /* no matching entry */
if ( typentry - > tupDesc = = NULL )
return ; /* tupdesc hasn't been requested */
/*
* Release our refcount and free the tupdesc if none remain . ( Can ' t use
* DecrTupleDescRefCount because this reference is not logged in current
* resource owner . )
*/
Assert ( typentry - > tupDesc - > tdrefcount > 0 ) ;
if ( - - typentry - > tupDesc - > tdrefcount = = 0 )
FreeTupleDesc ( typentry - > tupDesc ) ;
/* TypeCacheHash must exist, else this callback wouldn't be registered */
hash_seq_init ( & status , TypeCacheHash ) ;
while ( ( typentry = ( TypeCacheEntry * ) hash_seq_search ( & status ) ) ! = NULL )
{
if ( typentry - > tupDesc = = NULL )
continue ; /* not composite, or tupdesc hasn't been requested */
typentry - > tupDesc = NULL ;
/* Delete if match, or if we're zapping all composite types */
if ( relid = = typentry - > typrelid | | relid = = InvalidOid )
{
/*
* Release our refcount , and free the tupdesc if none remain .
* ( Can ' t use DecrTupleDescRefCount because this reference is not
* logged in current resource owner . )
*/
Assert ( typentry - > tupDesc - > tdrefcount > 0 ) ;
if ( - - typentry - > tupDesc - > tdrefcount = = 0 )
FreeTupleDesc ( typentry - > tupDesc ) ;
typentry - > tupDesc = NULL ;
}
}
}
Tom Lane
16 years ago