postgresql/src/include/utils/partcache.h

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/*-------------------------------------------------------------------------
*
* partcache.h
*
* Copyright (c) 1996-2024, PostgreSQL Global Development Group
*
* src/include/utils/partcache.h
*
*-------------------------------------------------------------------------
*/
#ifndef PARTCACHE_H
#define PARTCACHE_H
#include "access/attnum.h"
#include "fmgr.h"
#include "nodes/parsenodes.h"
#include "nodes/pg_list.h"
#include "nodes/primnodes.h"
#include "partitioning/partdefs.h"
#include "utils/relcache.h"
/*
* Information about the partition key of a relation
*/
typedef struct PartitionKeyData
{
PartitionStrategy strategy; /* partitioning strategy */
int16 partnatts; /* number of columns in the partition key */
AttrNumber *partattrs; /* attribute numbers of columns in the
* partition key or 0 if it's an expr */
List *partexprs; /* list of expressions in the partitioning
* key, one for each zero-valued partattrs */
Oid *partopfamily; /* OIDs of operator families */
Oid *partopcintype; /* OIDs of opclass declared input data types */
FmgrInfo *partsupfunc; /* lookup info for support funcs */
/* Partitioning collation per attribute */
Oid *partcollation;
/* Type information per attribute */
Oid *parttypid;
int32 *parttypmod;
int16 *parttyplen;
bool *parttypbyval;
char *parttypalign;
Oid *parttypcoll;
} PartitionKeyData;
Load relcache entries' partitioning data on-demand, not immediately. Formerly the rd_partkey and rd_partdesc data structures were always populated immediately when a relcache entry was built or rebuilt. This patch changes things so that they are populated only when they are first requested. (Hence, callers *must* now always use RelationGetPartitionKey or RelationGetPartitionDesc; just fetching the pointer directly is no longer acceptable.) This seems to have some performance benefits, but the main reason to do it is that it eliminates a recursive-reload failure that occurs if the partkey or partdesc expressions contain any references to the relation's rowtype (as discovered by Amit Langote). In retrospect, since loading these data structures might result in execution of nearly-arbitrary code via eval_const_expressions, it was a dumb idea to require that to happen during relcache entry rebuild. Also, fix things so that old copies of a relcache partition descriptor will be dropped when the cache entry's refcount goes to zero. In the previous coding it was possible for such copies to survive for the lifetime of the session, as I'd complained of in a previous discussion. (This management technique still isn't perfect, but it's better than before.) Improve the commentary explaining how that works and why it's safe to hand out direct pointers to these relcache substructures. In passing, improve RelationBuildPartitionDesc by using the same memory-context-parent-swap approach used by RelationBuildPartitionKey, thereby making it less dependent on strong assumptions about what partition_bounds_copy does. Avoid doing get_rel_relkind in the critical section, too. Patch by Amit Langote and Tom Lane; Robert Haas deserves some credit for prior work in the area, too. Although this is a pre-existing problem, no back-patch: the patch seems too invasive to be safe to back-patch, and the bug it fixes is a corner case that seems relatively unlikely to cause problems in the field. Discussion: https://postgr.es/m/CA+HiwqFUzjfj9HEsJtYWcr1SgQ_=iCAvQ=O2Sx6aQxoDu4OiHw@mail.gmail.com Discussion: https://postgr.es/m/CA+TgmoY3bRmGB6-DUnoVy5fJoreiBJ43rwMrQRCdPXuKt4Ykaw@mail.gmail.com
2019-12-25 20:43:13 +01:00
extern PartitionKey RelationGetPartitionKey(Relation rel);
extern List *RelationGetPartitionQual(Relation rel);
extern Expr *get_partition_qual_relid(Oid relid);
/*
* PartitionKey inquiry functions
*/
static inline int
get_partition_strategy(PartitionKey key)
{
return key->strategy;
}
static inline int
get_partition_natts(PartitionKey key)
{
return key->partnatts;
}
static inline List *
get_partition_exprs(PartitionKey key)
{
return key->partexprs;
}
/*
* PartitionKey inquiry functions - one column
*/
static inline int16
get_partition_col_attnum(PartitionKey key, int col)
{
return key->partattrs[col];
}
static inline Oid
get_partition_col_typid(PartitionKey key, int col)
{
return key->parttypid[col];
}
static inline int32
get_partition_col_typmod(PartitionKey key, int col)
{
return key->parttypmod[col];
}
static inline Oid
get_partition_col_collation(PartitionKey key, int col)
{
return key->partcollation[col];
}
#endif /* PARTCACHE_H */