1 /*-------------------------------------------------------------------------
4 * Low-level catalog cache definitions.
6 * NOTE: every catalog cache must have a corresponding unique index on
7 * the system table that it caches --- ie, the index must match the keys
8 * used to do lookups in this cache. All cache fetches are done with
9 * indexscans (under normal conditions). The index should be unique to
10 * guarantee that there can only be one matching row for a key combination.
13 * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
14 * Portions Copyright (c) 1994, Regents of the University of California
16 * src/include/utils/catcache.h
18 *-------------------------------------------------------------------------
23 #include "access/htup.h"
24 #include "access/skey.h"
25 #include "lib/ilist.h"
26 #include "utils/relcache.h"
29 * struct catctup: individual tuple in the cache.
30 * struct catclist: list of tuples matching a partial key.
31 * struct catcache: information for managing a cache.
32 * struct catcacheheader: information for managing all the caches.
35 #define CATCACHE_MAXKEYS 4
37 typedef struct catcache
39 int id; /* cache identifier --- see syscache.h */
40 slist_node cc_next; /* list link */
41 const char *cc_relname; /* name of relation the tuples come from */
42 Oid cc_reloid; /* OID of relation the tuples come from */
43 Oid cc_indexoid; /* OID of index matching cache keys */
44 bool cc_relisshared; /* is relation shared across databases? */
45 TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */
46 int cc_ntup; /* # of tuples currently in this cache */
47 int cc_nbuckets; /* # of hash buckets in this cache */
48 int cc_nkeys; /* # of keys (1..CATCACHE_MAXKEYS) */
49 int cc_key[CATCACHE_MAXKEYS]; /* AttrNumber of each key */
50 PGFunction cc_hashfunc[CATCACHE_MAXKEYS]; /* hash function for each key */
51 ScanKeyData cc_skey[CATCACHE_MAXKEYS]; /* precomputed key info for
53 bool cc_isname[CATCACHE_MAXKEYS]; /* flag "name" key columns */
54 dlist_head cc_lists; /* list of CatCList structs */
56 long cc_searches; /* total # searches against this cache */
57 long cc_hits; /* # of matches against existing entry */
58 long cc_neg_hits; /* # of matches against negative entry */
59 long cc_newloads; /* # of successful loads of new entry */
62 * cc_searches - (cc_hits + cc_neg_hits + cc_newloads) is number of failed
63 * searches, each of which will result in loading a negative entry
65 long cc_invals; /* # of entries invalidated from cache */
66 long cc_lsearches; /* total # list-searches */
67 long cc_lhits; /* # of matches against existing lists */
69 dlist_head *cc_bucket; /* hash buckets */
73 typedef struct catctup
75 int ct_magic; /* for identifying CatCTup entries */
76 #define CT_MAGIC 0x57261502
77 CatCache *my_cache; /* link to owning catcache */
80 * Each tuple in a cache is a member of a dlist that stores the elements
81 * of its hash bucket. We keep each dlist in LRU order to speed repeated
84 dlist_node cache_elem; /* list member of per-bucket list */
87 * The tuple may also be a member of at most one CatCList. (If a single
88 * catcache is list-searched with varying numbers of keys, we may have to
89 * make multiple entries for the same tuple because of this restriction.
90 * Currently, that's not expected to be common, so we accept the potential
93 struct catclist *c_list; /* containing CatCList, or NULL if none */
96 * A tuple marked "dead" must not be returned by subsequent searches.
97 * However, it won't be physically deleted from the cache until its
98 * refcount goes to zero. (If it's a member of a CatCList, the list's
99 * refcount must go to zero, too; also, remember to mark the list dead at
100 * the same time the tuple is marked.)
102 * A negative cache entry is an assertion that there is no tuple matching
103 * a particular key. This is just as useful as a normal entry so far as
104 * avoiding catalog searches is concerned. Management of positive and
105 * negative entries is identical.
107 int refcount; /* number of active references */
108 bool dead; /* dead but not yet removed? */
109 bool negative; /* negative cache entry? */
110 uint32 hash_value; /* hash value for this tuple's keys */
111 HeapTupleData tuple; /* tuple management header */
115 typedef struct catclist
117 int cl_magic; /* for identifying CatCList entries */
118 #define CL_MAGIC 0x52765103
119 CatCache *my_cache; /* link to owning catcache */
122 * A CatCList describes the result of a partial search, ie, a search using
123 * only the first K key columns of an N-key cache. We form the keys used
124 * into a tuple (with other attributes NULL) to represent the stored key
125 * set. The CatCList object contains links to cache entries for all the
126 * table rows satisfying the partial key. (Note: none of these will be
127 * negative cache entries.)
129 * A CatCList is only a member of a per-cache list; we do not currently
130 * divide them into hash buckets.
132 * A list marked "dead" must not be returned by subsequent searches.
133 * However, it won't be physically deleted from the cache until its
134 * refcount goes to zero. (A list should be marked dead if any of its
135 * member entries are dead.)
137 * If "ordered" is true then the member tuples appear in the order of the
138 * cache's underlying index. This will be true in normal operation, but
139 * might not be true during bootstrap or recovery operations. (namespace.c
140 * is able to save some cycles when it is true.)
142 dlist_node cache_elem; /* list member of per-catcache list */
143 int refcount; /* number of active references */
144 bool dead; /* dead but not yet removed? */
145 bool ordered; /* members listed in index order? */
146 short nkeys; /* number of lookup keys specified */
147 uint32 hash_value; /* hash value for lookup keys */
148 HeapTupleData tuple; /* header for tuple holding keys */
149 int n_members; /* number of member tuples */
150 CatCTup *members[1]; /* members --- VARIABLE LENGTH ARRAY */
151 } CatCList; /* VARIABLE LENGTH STRUCT */
154 typedef struct catcacheheader
156 slist_head ch_caches; /* head of list of CatCache structs */
157 int ch_ntup; /* # of tuples in all caches */
161 /* this extern duplicates utils/memutils.h... */
162 extern PGDLLIMPORT MemoryContext CacheMemoryContext;
164 extern void CreateCacheMemoryContext(void);
165 extern void AtEOXact_CatCache(bool isCommit);
167 extern CatCache *InitCatCache(int id, Oid reloid, Oid indexoid,
168 int nkeys, const int *key,
170 extern void InitCatCachePhase2(CatCache *cache, bool touch_index);
172 extern HeapTuple SearchCatCache(CatCache *cache,
175 extern void ReleaseCatCache(HeapTuple tuple);
177 extern uint32 GetCatCacheHashValue(CatCache *cache,
181 extern CatCList *SearchCatCacheList(CatCache *cache, int nkeys,
184 extern void ReleaseCatCacheList(CatCList *list);
186 extern void ResetCatalogCaches(void);
187 extern void CatalogCacheFlushCatalog(Oid catId);
188 extern void CatalogCacheIdInvalidate(int cacheId, uint32 hashValue);
189 extern void PrepareToInvalidateCacheTuple(Relation relation,
192 void (*function) (int, uint32, Oid));
194 extern void PrintCatCacheLeakWarning(HeapTuple tuple);
195 extern void PrintCatCacheListLeakWarning(CatCList *list);
197 #endif /* CATCACHE_H */