1 /*-------------------------------------------------------------------------
2 *
3 * rewriteRemove.c
4 * routines for removing rewrite rules
5 *
6 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/rewrite/rewriteRemove.c
12 *
13 *-------------------------------------------------------------------------
14 */
15 #include "postgres.h"
16
17 #include "access/genam.h"
18 #include "access/htup_details.h"
19 #include "access/sysattr.h"
20 #include "access/table.h"
21 #include "catalog/catalog.h"
22 #include "catalog/dependency.h"
23 #include "catalog/indexing.h"
24 #include "catalog/namespace.h"
25 #include "catalog/pg_rewrite.h"
26 #include "miscadmin.h"
27 #include "rewrite/rewriteRemove.h"
28 #include "utils/acl.h"
29 #include "utils/fmgroids.h"
30 #include "utils/inval.h"
31 #include "utils/lsyscache.h"
32 #include "utils/rel.h"
33 #include "utils/syscache.h"
34
35 /*
36 * Guts of rule deletion.
37 */
38 void
RemoveRewriteRuleById(Oid ruleOid)39 RemoveRewriteRuleById(Oid ruleOid)
40 {
41 Relation RewriteRelation;
42 ScanKeyData skey[1];
43 SysScanDesc rcscan;
44 Relation event_relation;
45 HeapTuple tuple;
46 Oid eventRelationOid;
47
48 /*
49 * Open the pg_rewrite relation.
50 */
51 RewriteRelation = table_open(RewriteRelationId, RowExclusiveLock);
52
53 /*
54 * Find the tuple for the target rule.
55 */
56 ScanKeyInit(&skey[0],
57 Anum_pg_rewrite_oid,
58 BTEqualStrategyNumber, F_OIDEQ,
59 ObjectIdGetDatum(ruleOid));
60
61 rcscan = systable_beginscan(RewriteRelation, RewriteOidIndexId, true,
62 NULL, 1, skey);
63
64 tuple = systable_getnext(rcscan);
65
66 if (!HeapTupleIsValid(tuple))
67 elog(ERROR, "could not find tuple for rule %u", ruleOid);
68
69 /*
70 * We had better grab AccessExclusiveLock to ensure that no queries are
71 * going on that might depend on this rule. (Note: a weaker lock would
72 * suffice if it's not an ON SELECT rule.)
73 */
74 eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class;
75 event_relation = table_open(eventRelationOid, AccessExclusiveLock);
76
77 if (!allowSystemTableMods && IsSystemRelation(event_relation))
78 ereport(ERROR,
79 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
80 errmsg("permission denied: \"%s\" is a system catalog",
81 RelationGetRelationName(event_relation))));
82
83 /*
84 * Now delete the pg_rewrite tuple for the rule
85 */
86 CatalogTupleDelete(RewriteRelation, &tuple->t_self);
87
88 systable_endscan(rcscan);
89
90 table_close(RewriteRelation, RowExclusiveLock);
91
92 /*
93 * Issue shared-inval notice to force all backends (including me!) to
94 * update relcache entries with the new rule set.
95 */
96 CacheInvalidateRelcache(event_relation);
97
98 /* Close rel, but keep lock till commit... */
99 table_close(event_relation, NoLock);
100 }
101