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catcache.h
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1 /*-------------------------------------------------------------------------
2  *
3  * catcache.h
4  * Low-level catalog cache definitions.
5  *
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.
11  *
12  *
13  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
14  * Portions Copyright (c) 1994, Regents of the University of California
15  *
16  * src/include/utils/catcache.h
17  *
18  *-------------------------------------------------------------------------
19  */
20 #ifndef CATCACHE_H
21 #define CATCACHE_H
22 
23 #include "access/htup.h"
24 #include "access/skey.h"
25 #include "lib/ilist.h"
26 #include "utils/relcache.h"
27 
28 /*
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.
33  */
34 
35 #define CATCACHE_MAXKEYS 4
36 
37 
38 /* function computing a datum's hash */
39 typedef uint32 (*CCHashFN) (Datum datum);
40 
41 /* function computing equality of two datums */
42 typedef bool (*CCFastEqualFN) (Datum a, Datum b);
43 
44 typedef struct catcache
45 {
46  int id; /* cache identifier --- see syscache.h */
47  int cc_nbuckets; /* # of hash buckets in this cache */
48  TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */
49  dlist_head *cc_bucket; /* hash buckets */
50  CCHashFN cc_hashfunc[CATCACHE_MAXKEYS]; /* hash function for each key */
51  CCFastEqualFN cc_fastequal[CATCACHE_MAXKEYS]; /* fast equal function for
52  * each key */
53  int cc_keyno[CATCACHE_MAXKEYS]; /* AttrNumber of each key */
54  int cc_nkeys; /* # of keys (1..CATCACHE_MAXKEYS) */
55  int cc_ntup; /* # of tuples currently in this cache */
56  int cc_nlist; /* # of CatCLists currently in this cache */
57  int cc_nlbuckets; /* # of CatCList hash buckets in this cache */
58  dlist_head *cc_lbucket; /* hash buckets for CatCLists */
59  const char *cc_relname; /* name of relation the tuples come from */
60  Oid cc_reloid; /* OID of relation the tuples come from */
61  Oid cc_indexoid; /* OID of index matching cache keys */
62  bool cc_relisshared; /* is relation shared across databases? */
63  slist_node cc_next; /* list link */
64  ScanKeyData cc_skey[CATCACHE_MAXKEYS]; /* precomputed key info for heap
65  * scans */
66 
67  /*
68  * Keep these at the end, so that compiling catcache.c with CATCACHE_STATS
69  * doesn't break ABI for other modules
70  */
71 #ifdef CATCACHE_STATS
72  long cc_searches; /* total # searches against this cache */
73  long cc_hits; /* # of matches against existing entry */
74  long cc_neg_hits; /* # of matches against negative entry */
75  long cc_newloads; /* # of successful loads of new entry */
76 
77  /*
78  * cc_searches - (cc_hits + cc_neg_hits + cc_newloads) is number of failed
79  * searches, each of which will result in loading a negative entry
80  */
81  long cc_invals; /* # of entries invalidated from cache */
82  long cc_lsearches; /* total # list-searches */
83  long cc_lhits; /* # of matches against existing lists */
84 #endif
86 
87 
88 typedef struct catctup
89 {
90  int ct_magic; /* for identifying CatCTup entries */
91 #define CT_MAGIC 0x57261502
92 
93  uint32 hash_value; /* hash value for this tuple's keys */
94 
95  /*
96  * Lookup keys for the entry. By-reference datums point into the tuple for
97  * positive cache entries, and are separately allocated for negative ones.
98  */
100 
101  /*
102  * Each tuple in a cache is a member of a dlist that stores the elements
103  * of its hash bucket. We keep each dlist in LRU order to speed repeated
104  * lookups.
105  */
106  dlist_node cache_elem; /* list member of per-bucket list */
107 
108  /*
109  * A tuple marked "dead" must not be returned by subsequent searches.
110  * However, it won't be physically deleted from the cache until its
111  * refcount goes to zero. (If it's a member of a CatCList, the list's
112  * refcount must go to zero, too; also, remember to mark the list dead at
113  * the same time the tuple is marked.)
114  *
115  * A negative cache entry is an assertion that there is no tuple matching
116  * a particular key. This is just as useful as a normal entry so far as
117  * avoiding catalog searches is concerned. Management of positive and
118  * negative entries is identical.
119  */
120  int refcount; /* number of active references */
121  bool dead; /* dead but not yet removed? */
122  bool negative; /* negative cache entry? */
123  HeapTupleData tuple; /* tuple management header */
124 
125  /*
126  * The tuple may also be a member of at most one CatCList. (If a single
127  * catcache is list-searched with varying numbers of keys, we may have to
128  * make multiple entries for the same tuple because of this restriction.
129  * Currently, that's not expected to be common, so we accept the potential
130  * inefficiency.)
131  */
132  struct catclist *c_list; /* containing CatCList, or NULL if none */
133 
134  CatCache *my_cache; /* link to owning catcache */
135  /* properly aligned tuple data follows, unless a negative entry */
137 
138 
139 /*
140  * A CatCList describes the result of a partial search, ie, a search using
141  * only the first K key columns of an N-key cache. We store the keys used
142  * into the keys attribute to represent the stored key set. The CatCList
143  * object contains links to cache entries for all the table rows satisfying
144  * the partial key. (Note: none of these will be negative cache entries.)
145  *
146  * A CatCList is only a member of a per-cache list; we do not currently
147  * divide them into hash buckets.
148  *
149  * A list marked "dead" must not be returned by subsequent searches.
150  * However, it won't be physically deleted from the cache until its
151  * refcount goes to zero. (A list should be marked dead if any of its
152  * member entries are dead.)
153  *
154  * If "ordered" is true then the member tuples appear in the order of the
155  * cache's underlying index. This will be true in normal operation, but
156  * might not be true during bootstrap or recovery operations. (namespace.c
157  * is able to save some cycles when it is true.)
158  */
159 typedef struct catclist
160 {
161  int cl_magic; /* for identifying CatCList entries */
162 #define CL_MAGIC 0x52765103
163 
164  uint32 hash_value; /* hash value for lookup keys */
165 
166  dlist_node cache_elem; /* list member of per-catcache list */
167 
168  /*
169  * Lookup keys for the entry, with the first nkeys elements being valid.
170  * All by-reference are separately allocated.
171  */
173 
174  int refcount; /* number of active references */
175  bool dead; /* dead but not yet removed? */
176  bool ordered; /* members listed in index order? */
177  short nkeys; /* number of lookup keys specified */
178  int n_members; /* number of member tuples */
179  CatCache *my_cache; /* link to owning catcache */
182 
183 
184 typedef struct catcacheheader
185 {
186  slist_head ch_caches; /* head of list of CatCache structs */
187  int ch_ntup; /* # of tuples in all caches */
189 
190 
191 /* this extern duplicates utils/memutils.h... */
193 
194 extern void CreateCacheMemoryContext(void);
195 
196 extern CatCache *InitCatCache(int id, Oid reloid, Oid indexoid,
197  int nkeys, const int *key,
198  int nbuckets);
199 extern void InitCatCachePhase2(CatCache *cache, bool touch_index);
200 
201 extern HeapTuple SearchCatCache(CatCache *cache,
202  Datum v1, Datum v2, Datum v3, Datum v4);
203 extern HeapTuple SearchCatCache1(CatCache *cache,
204  Datum v1);
205 extern HeapTuple SearchCatCache2(CatCache *cache,
206  Datum v1, Datum v2);
207 extern HeapTuple SearchCatCache3(CatCache *cache,
208  Datum v1, Datum v2, Datum v3);
209 extern HeapTuple SearchCatCache4(CatCache *cache,
210  Datum v1, Datum v2, Datum v3, Datum v4);
211 extern void ReleaseCatCache(HeapTuple tuple);
212 
213 extern uint32 GetCatCacheHashValue(CatCache *cache,
214  Datum v1, Datum v2,
215  Datum v3, Datum v4);
216 
217 extern CatCList *SearchCatCacheList(CatCache *cache, int nkeys,
218  Datum v1, Datum v2,
219  Datum v3);
220 extern void ReleaseCatCacheList(CatCList *list);
221 
222 extern void ResetCatalogCaches(void);
223 extern void CatalogCacheFlushCatalog(Oid catId);
224 extern void CatCacheInvalidate(CatCache *cache, uint32 hashValue);
225 extern void PrepareToInvalidateCacheTuple(Relation relation,
226  HeapTuple tuple,
227  HeapTuple newtuple,
228  void (*function) (int, uint32, Oid, void *),
229  void *context);
230 
231 #endif /* CATCACHE_H */
unsigned int uint32
Definition: c.h:492
#define PGDLLIMPORT
Definition: c.h:1295
#define FLEXIBLE_ARRAY_MEMBER
Definition: c.h:413
HeapTuple SearchCatCache2(CatCache *cache, Datum v1, Datum v2)
Definition: catcache.c:1287
HeapTuple SearchCatCache3(CatCache *cache, Datum v1, Datum v2, Datum v3)
Definition: catcache.c:1295
void ReleaseCatCacheList(CatCList *list)
Definition: catcache.c:1985
void InitCatCachePhase2(CatCache *cache, bool touch_index)
Definition: catcache.c:1145
void ResetCatalogCaches(void)
Definition: catcache.c:754
uint32(* CCHashFN)(Datum datum)
Definition: catcache.h:39
uint32 GetCatCacheHashValue(CatCache *cache, Datum v1, Datum v2, Datum v3, Datum v4)
Definition: catcache.c:1612
#define CATCACHE_MAXKEYS
Definition: catcache.h:35
HeapTuple SearchCatCache4(CatCache *cache, Datum v1, Datum v2, Datum v3, Datum v4)
Definition: catcache.c:1303
bool(* CCFastEqualFN)(Datum a, Datum b)
Definition: catcache.h:42
void PrepareToInvalidateCacheTuple(Relation relation, HeapTuple tuple, HeapTuple newtuple, void(*function)(int, uint32, Oid, void *), void *context)
Definition: catcache.c:2286
struct catcache CatCache
struct catctup CatCTup
CatCache * InitCatCache(int id, Oid reloid, Oid indexoid, int nkeys, const int *key, int nbuckets)
Definition: catcache.c:828
CatCList * SearchCatCacheList(CatCache *cache, int nkeys, Datum v1, Datum v2, Datum v3)
Definition: catcache.c:1646
void CreateCacheMemoryContext(void)
Definition: catcache.c:680
struct catclist CatCList
PGDLLIMPORT MemoryContext CacheMemoryContext
Definition: mcxt.c:152
void CatCacheInvalidate(CatCache *cache, uint32 hashValue)
Definition: catcache.c:607
HeapTuple SearchCatCache1(CatCache *cache, Datum v1)
Definition: catcache.c:1279
void CatalogCacheFlushCatalog(Oid catId)
Definition: catcache.c:784
struct catcacheheader CatCacheHeader
void ReleaseCatCache(HeapTuple tuple)
Definition: catcache.c:1573
HeapTuple SearchCatCache(CatCache *cache, Datum v1, Datum v2, Datum v3, Datum v4)
Definition: catcache.c:1262
int b
Definition: isn.c:69
int a
Definition: isn.c:68
uintptr_t Datum
Definition: postgres.h:64
unsigned int Oid
Definition: postgres_ext.h:31
tree context
Definition: radixtree.h:1835
const char * cc_relname
Definition: catcache.h:59
CCHashFN cc_hashfunc[CATCACHE_MAXKEYS]
Definition: catcache.h:50
dlist_head * cc_bucket
Definition: catcache.h:49
slist_node cc_next
Definition: catcache.h:63
Oid cc_reloid
Definition: catcache.h:60
int cc_nkeys
Definition: catcache.h:54
int cc_keyno[CATCACHE_MAXKEYS]
Definition: catcache.h:53
CCFastEqualFN cc_fastequal[CATCACHE_MAXKEYS]
Definition: catcache.h:51
Oid cc_indexoid
Definition: catcache.h:61
int cc_nbuckets
Definition: catcache.h:47
bool cc_relisshared
Definition: catcache.h:62
int cc_ntup
Definition: catcache.h:55
ScanKeyData cc_skey[CATCACHE_MAXKEYS]
Definition: catcache.h:64
int cc_nlist
Definition: catcache.h:56
int id
Definition: catcache.h:46
TupleDesc cc_tupdesc
Definition: catcache.h:48
int cc_nlbuckets
Definition: catcache.h:57
dlist_head * cc_lbucket
Definition: catcache.h:58
slist_head ch_caches
Definition: catcache.h:186
dlist_node cache_elem
Definition: catcache.h:166
int refcount
Definition: catcache.h:174
CatCache * my_cache
Definition: catcache.h:179
int cl_magic
Definition: catcache.h:161
bool dead
Definition: catcache.h:175
short nkeys
Definition: catcache.h:177
Datum keys[CATCACHE_MAXKEYS]
Definition: catcache.h:172
bool ordered
Definition: catcache.h:176
CatCTup * members[FLEXIBLE_ARRAY_MEMBER]
Definition: catcache.h:180
uint32 hash_value
Definition: catcache.h:164
int n_members
Definition: catcache.h:178
int ct_magic
Definition: catcache.h:90
int refcount
Definition: catcache.h:120
bool negative
Definition: catcache.h:122
dlist_node cache_elem
Definition: catcache.h:106
HeapTupleData tuple
Definition: catcache.h:123
CatCache * my_cache
Definition: catcache.h:134
struct catclist * c_list
Definition: catcache.h:132
Datum keys[CATCACHE_MAXKEYS]
Definition: catcache.h:99
bool dead
Definition: catcache.h:121
uint32 hash_value
Definition: catcache.h:93