PostgreSQL Source Code: src/backend/utils/cache/spccache.c Source File

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spccache.c
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1/*-------------------------------------------------------------------------
2 *
3 * spccache.c
4 * Tablespace cache management.
5 *
6 * We cache the parsed version of spcoptions for each tablespace to avoid
7 * needing to reparse on every lookup. Right now, there doesn't appear to
8 * be a measurable performance gain from doing this, but that might change
9 * in the future as we add more options.
10 *
11 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
12 * Portions Copyright (c) 1994, Regents of the University of California
13 *
14 * IDENTIFICATION
15 * src/backend/utils/cache/spccache.c
16 *
17 *-------------------------------------------------------------------------
18 */
19#include "postgres.h"
20
21#include "access/reloptions.h"
22#include "catalog/pg_tablespace.h"
23#include "commands/tablespace.h"
24#include "miscadmin.h"
25#include "optimizer/optimizer.h"
26#include "storage/bufmgr.h"
27#include "utils/catcache.h"
28#include "utils/hsearch.h"
29#include "utils/inval.h"
30#include "utils/spccache.h"
31#include "utils/syscache.h"
32#include "varatt.h"
33
34
35/* Hash table for information about each tablespace */
36 static HTAB *TableSpaceCacheHash = NULL;
37
38 typedef struct
39{
40 Oid oid; /* lookup key - must be first */
41 TableSpaceOpts *opts; /* options, or NULL if none */
42} TableSpaceCacheEntry;
43
44
45/*
46 * InvalidateTableSpaceCacheCallback
47 * Flush all cache entries when pg_tablespace is updated.
48 *
49 * When pg_tablespace is updated, we must flush the cache entry at least
50 * for that tablespace. Currently, we just flush them all. This is quick
51 * and easy and doesn't cost much, since there shouldn't be terribly many
52 * tablespaces, nor do we expect them to be frequently modified.
53 */
54static void
55 InvalidateTableSpaceCacheCallback(Datum arg, int cacheid, uint32 hashvalue)
56{
57 HASH_SEQ_STATUS status;
58 TableSpaceCacheEntry *spc;
59
60 hash_seq_init(&status, TableSpaceCacheHash);
61 while ((spc = (TableSpaceCacheEntry *) hash_seq_search(&status)) != NULL)
62 {
63 if (spc->opts)
64 pfree(spc->opts);
65 if (hash_search(TableSpaceCacheHash,
66 &spc->oid,
67 HASH_REMOVE,
68 NULL) == NULL)
69 elog(ERROR, "hash table corrupted");
70 }
71}
72
73/*
74 * InitializeTableSpaceCache
75 * Initialize the tablespace cache.
76 */
77static void
78 InitializeTableSpaceCache(void)
79{
80 HASHCTL ctl;
81
82 /* Initialize the hash table. */
83 ctl.keysize = sizeof(Oid);
84 ctl.entrysize = sizeof(TableSpaceCacheEntry);
85 TableSpaceCacheHash =
86 hash_create("TableSpace cache", 16, &ctl,
87 HASH_ELEM | HASH_BLOBS);
88
89 /* Make sure we've initialized CacheMemoryContext. */
90 if (!CacheMemoryContext)
91 CreateCacheMemoryContext();
92
93 /* Watch for invalidation events. */
94 CacheRegisterSyscacheCallback(TABLESPACEOID,
95 InvalidateTableSpaceCacheCallback,
96 (Datum) 0);
97}
98
99/*
100 * get_tablespace
101 * Fetch TableSpaceCacheEntry structure for a specified table OID.
102 *
103 * Pointers returned by this function should not be stored, since a cache
104 * flush will invalidate them.
105 */
106static TableSpaceCacheEntry *
107 get_tablespace(Oid spcid)
108{
109 TableSpaceCacheEntry *spc;
110 HeapTuple tp;
111 TableSpaceOpts *opts;
112
113 /*
114 * Since spcid is always from a pg_class tuple, InvalidOid implies the
115 * default.
116 */
117 if (spcid == InvalidOid)
118 spcid = MyDatabaseTableSpace;
119
120 /* Find existing cache entry, if any. */
121 if (!TableSpaceCacheHash)
122 InitializeTableSpaceCache();
123 spc = (TableSpaceCacheEntry *) hash_search(TableSpaceCacheHash,
124 &spcid,
125 HASH_FIND,
126 NULL);
127 if (spc)
128 return spc;
129
130 /*
131 * Not found in TableSpace cache. Check catcache. If we don't find a
132 * valid HeapTuple, it must mean someone has managed to request tablespace
133 * details for a non-existent tablespace. We'll just treat that case as
134 * if no options were specified.
135 */
136 tp = SearchSysCache1(TABLESPACEOID, ObjectIdGetDatum(spcid));
137 if (!HeapTupleIsValid(tp))
138 opts = NULL;
139 else
140 {
141 Datum datum;
142 bool isNull;
143
144 datum = SysCacheGetAttr(TABLESPACEOID,
145 tp,
146 Anum_pg_tablespace_spcoptions,
147 &isNull);
148 if (isNull)
149 opts = NULL;
150 else
151 {
152 bytea *bytea_opts = tablespace_reloptions(datum, false);
153
154 opts = MemoryContextAlloc(CacheMemoryContext, VARSIZE(bytea_opts));
155 memcpy(opts, bytea_opts, VARSIZE(bytea_opts));
156 }
157 ReleaseSysCache(tp);
158 }
159
160 /*
161 * Now create the cache entry. It's important to do this only after
162 * reading the pg_tablespace entry, since doing so could cause a cache
163 * flush.
164 */
165 spc = (TableSpaceCacheEntry *) hash_search(TableSpaceCacheHash,
166 &spcid,
167 HASH_ENTER,
168 NULL);
169 spc->opts = opts;
170 return spc;
171}
172
173/*
174 * get_tablespace_page_costs
175 * Return random and/or sequential page costs for a given tablespace.
176 *
177 * This value is not locked by the transaction, so this value may
178 * be changed while a SELECT that has used these values for planning
179 * is still executing.
180 */
181void
182 get_tablespace_page_costs(Oid spcid,
183 double *spc_random_page_cost,
184 double *spc_seq_page_cost)
185{
186 TableSpaceCacheEntry *spc = get_tablespace(spcid);
187
188 Assert(spc != NULL);
189
190 if (spc_random_page_cost)
191 {
192 if (!spc->opts || spc->opts->random_page_cost < 0)
193 *spc_random_page_cost = random_page_cost;
194 else
195 *spc_random_page_cost = spc->opts->random_page_cost;
196 }
197
198 if (spc_seq_page_cost)
199 {
200 if (!spc->opts || spc->opts->seq_page_cost < 0)
201 *spc_seq_page_cost = seq_page_cost;
202 else
203 *spc_seq_page_cost = spc->opts->seq_page_cost;
204 }
205}
206
207/*
208 * get_tablespace_io_concurrency
209 *
210 * This value is not locked by the transaction, so this value may
211 * be changed while a SELECT that has used these values for planning
212 * is still executing.
213 */
214int
215 get_tablespace_io_concurrency(Oid spcid)
216{
217 TableSpaceCacheEntry *spc = get_tablespace(spcid);
218
219 if (!spc->opts || spc->opts->effective_io_concurrency < 0)
220 return effective_io_concurrency;
221 else
222 return spc->opts->effective_io_concurrency;
223}
224
225/*
226 * get_tablespace_maintenance_io_concurrency
227 */
228int
229 get_tablespace_maintenance_io_concurrency(Oid spcid)
230{
231 TableSpaceCacheEntry *spc = get_tablespace(spcid);
232
233 if (!spc->opts || spc->opts->maintenance_io_concurrency < 0)
234 return maintenance_io_concurrency;
235 else
236 return spc->opts->maintenance_io_concurrency;
237}
int maintenance_io_concurrency
Definition: bufmgr.c:162
int effective_io_concurrency
Definition: bufmgr.c:155
uint32_t uint32
Definition: c.h:538
void CreateCacheMemoryContext(void)
Definition: catcache.c:709
double random_page_cost
Definition: costsize.c:131
double seq_page_cost
Definition: costsize.c:130
void * hash_search(HTAB *hashp, const void *keyPtr, HASHACTION action, bool *foundPtr)
Definition: dynahash.c:952
HTAB * hash_create(const char *tabname, int64 nelem, const HASHCTL *info, int flags)
Definition: dynahash.c:358
void * hash_seq_search(HASH_SEQ_STATUS *status)
Definition: dynahash.c:1415
void hash_seq_init(HASH_SEQ_STATUS *status, HTAB *hashp)
Definition: dynahash.c:1380
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:226
Oid MyDatabaseTableSpace
Definition: globals.c:96
Assert(PointerIsAligned(start, uint64))
@ HASH_FIND
Definition: hsearch.h:113
@ HASH_REMOVE
Definition: hsearch.h:115
@ HASH_ENTER
Definition: hsearch.h:114
#define HASH_ELEM
Definition: hsearch.h:95
#define HASH_BLOBS
Definition: hsearch.h:97
#define HeapTupleIsValid(tuple)
Definition: htup.h:78
void CacheRegisterSyscacheCallback(int cacheid, SyscacheCallbackFunction func, Datum arg)
Definition: inval.c:1812
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:1229
void pfree(void *pointer)
Definition: mcxt.c:1594
MemoryContext CacheMemoryContext
Definition: mcxt.c:169
static AmcheckOptions opts
Definition: pg_amcheck.c:112
void * arg
static Datum ObjectIdGetDatum(Oid X)
Definition: postgres.h:262
uint64_t Datum
Definition: postgres.h:70
#define InvalidOid
Definition: postgres_ext.h:37
unsigned int Oid
Definition: postgres_ext.h:32
tree ctl
Definition: radixtree.h:1838
bytea * tablespace_reloptions(Datum reloptions, bool validate)
Definition: reloptions.c:2122
static TableSpaceCacheEntry * get_tablespace(Oid spcid)
Definition: spccache.c:107
static void InvalidateTableSpaceCacheCallback(Datum arg, int cacheid, uint32 hashvalue)
Definition: spccache.c:55
int get_tablespace_io_concurrency(Oid spcid)
Definition: spccache.c:215
static void InitializeTableSpaceCache(void)
Definition: spccache.c:78
void get_tablespace_page_costs(Oid spcid, double *spc_random_page_cost, double *spc_seq_page_cost)
Definition: spccache.c:182
static HTAB * TableSpaceCacheHash
Definition: spccache.c:36
int get_tablespace_maintenance_io_concurrency(Oid spcid)
Definition: spccache.c:229
Definition: hsearch.h:66
Definition: hsearch.h:121
Definition: dynahash.c:222
TableSpaceOpts * opts
Definition: spccache.c:41
int maintenance_io_concurrency
Definition: tablespace.h:47
float8 random_page_cost
Definition: tablespace.h:44
int effective_io_concurrency
Definition: tablespace.h:46
float8 seq_page_cost
Definition: tablespace.h:45
Definition: c.h:692
void ReleaseSysCache(HeapTuple tuple)
Definition: syscache.c:264
HeapTuple SearchSysCache1(int cacheId, Datum key1)
Definition: syscache.c:220
Datum SysCacheGetAttr(int cacheId, HeapTuple tup, AttrNumber attributeNumber, bool *isNull)
Definition: syscache.c:595
static Size VARSIZE(const void *PTR)
Definition: varatt.h:298

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