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bbbc00af88
SI messages now include the relevant database OID, so that operations in one database do not cause useless cache flushes in backends attached to other databases. Declare SI messages properly using a union, to eliminate the former assumption that Oid is the same size as int or Index. Rewrite the nearly-unreadable code in inval.c, and document it better. Arrange for catcache flushes at end of command/transaction to happen before relcache flushes do --- this avoids loading a new tuple into the catcache while setting up new relcache entry, only to have it be flushed again immediately.
106 lines
3.8 KiB
C
106 lines
3.8 KiB
C
/*-------------------------------------------------------------------------
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*
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* catcache.h
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* Low-level catalog cache definitions.
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*
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* NOTE: every catalog cache must have a corresponding unique index on
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* the system table that it caches --- ie, the index must match the keys
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* used to do lookups in this cache. All cache fetches are done with
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* indexscans (under normal conditions). The index should be unique to
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* guarantee that there can only be one matching row for a key combination.
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*
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*
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: catcache.h,v 1.34 2001/06/19 19:42:16 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef CATCACHE_H
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#define CATCACHE_H
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#include "access/htup.h"
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#include "lib/dllist.h"
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/*
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* struct catctup: individual tuple in the cache.
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* struct catcache: information for managing a cache.
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* struct catcacheheader: information for managing all the caches.
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*/
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typedef struct catcache
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{
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int id; /* cache identifier --- see syscache.h */
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struct catcache *cc_next; /* link to next catcache */
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char *cc_relname; /* name of relation the tuples come from */
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char *cc_indname; /* name of index matching cache keys */
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int cc_reloidattr; /* AttrNumber of relation OID, or 0 */
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bool cc_relisshared; /* is relation shared? */
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TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */
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int cc_ntup; /* # of tuples currently in this cache */
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int cc_size; /* # of hash buckets in this cache */
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int cc_nkeys; /* number of keys (1..4) */
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int cc_key[4]; /* AttrNumber of each key */
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PGFunction cc_hashfunc[4]; /* hash function to use for each key */
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ScanKeyData cc_skey[4]; /* precomputed key info for heap scans */
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Dllist cc_bucket[1]; /* hash buckets --- VARIABLE LENGTH ARRAY */
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} CatCache; /* VARIABLE LENGTH STRUCT */
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typedef struct catctup
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{
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int ct_magic; /* for Assert checks */
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#define CT_MAGIC 0x57261502
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CatCache *my_cache; /* link to owning catcache */
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/*
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* Each tuple in a cache is a member of two lists: one lists all the
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* elements in all the caches in LRU order, and the other lists just
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* the elements in one hashbucket of one cache, also in LRU order.
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*
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* A tuple marked "dead" must not be returned by subsequent searches.
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* However, it won't be physically deleted from the cache until its
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* refcount goes to zero.
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*/
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Dlelem lrulist_elem; /* list member of global LRU list */
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Dlelem cache_elem; /* list member of per-bucket list */
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int refcount; /* number of active references */
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bool dead; /* dead but not yet removed? */
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HeapTupleData tuple; /* tuple management header */
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} CatCTup;
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typedef struct catcacheheader
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{
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CatCache *ch_caches; /* head of list of CatCache structs */
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int ch_ntup; /* # of tuples in all caches */
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int ch_maxtup; /* max # of tuples allowed (LRU) */
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Dllist ch_lrulist; /* overall LRU list, most recent first */
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} CatCacheHeader;
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/* this extern duplicates utils/memutils.h... */
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extern MemoryContext CacheMemoryContext;
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extern void CreateCacheMemoryContext(void);
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extern void AtEOXact_CatCache(bool isCommit);
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extern CatCache *InitCatCache(int id, char *relname, char *indname,
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int reloidattr,
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int nkeys, int *key);
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extern HeapTuple SearchCatCache(CatCache *cache,
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Datum v1, Datum v2,
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Datum v3, Datum v4);
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extern void ReleaseCatCache(HeapTuple tuple);
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extern void ResetCatalogCaches(void);
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extern void CatalogCacheFlushRelation(Oid relId);
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extern void CatalogCacheIdInvalidate(int cacheId, Index hashIndex,
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ItemPointer pointer);
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extern void PrepareToInvalidateCacheTuple(Relation relation,
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HeapTuple tuple,
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void (*function) (int, Index, ItemPointer, Oid));
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#endif /* CATCACHE_H */
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