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rewriteRemove.c
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1 /*-------------------------------------------------------------------------
2  *
3  * rewriteRemove.c
4  * routines for removing rewrite rules
5  *
6  * Portions Copyright (c) 1996-2023, 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
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 }
bool IsSystemRelation(Relation relation)
Definition: catalog.c:75
int errcode(int sqlerrcode)
Definition: elog.c:858
int errmsg(const char *fmt,...)
Definition: elog.c:1069
#define ERROR
Definition: elog.h:39
#define ereport(elevel,...)
Definition: elog.h:149
void systable_endscan(SysScanDesc sysscan)
Definition: genam.c:599
HeapTuple systable_getnext(SysScanDesc sysscan)
Definition: genam.c:506
SysScanDesc systable_beginscan(Relation heapRelation, Oid indexId, bool indexOK, Snapshot snapshot, int nkeys, ScanKey key)
Definition: genam.c:387
bool allowSystemTableMods
Definition: globals.c:124
#define HeapTupleIsValid(tuple)
Definition: htup.h:78
#define GETSTRUCT(TUP)
Definition: htup_details.h:653
void CatalogTupleDelete(Relation heapRel, ItemPointer tid)
Definition: indexing.c:365
void CacheInvalidateRelcache(Relation relation)
Definition: inval.c:1363
#define NoLock
Definition: lockdefs.h:34
#define AccessExclusiveLock
Definition: lockdefs.h:43
#define RowExclusiveLock
Definition: lockdefs.h:38
FormData_pg_rewrite * Form_pg_rewrite
Definition: pg_rewrite.h:52
static Datum ObjectIdGetDatum(Oid X)
Definition: postgres.h:252
unsigned int Oid
Definition: postgres_ext.h:31
#define RelationGetRelationName(relation)
Definition: rel.h:538
void RemoveRewriteRuleById(Oid ruleOid)
Definition: rewriteRemove.c:39
void ScanKeyInit(ScanKey entry, AttrNumber attributeNumber, StrategyNumber strategy, RegProcedure procedure, Datum argument)
Definition: scankey.c:76
#define BTEqualStrategyNumber
Definition: stratnum.h:31
ItemPointerData t_self
Definition: htup.h:65
void table_close(Relation relation, LOCKMODE lockmode)
Definition: table.c:126
Relation table_open(Oid relationId, LOCKMODE lockmode)
Definition: table.c:40