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# Disallow TRUNCATE on tables that are involved in referential

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constraints


The issue with finding and removing foreign key constraints is no longer
an issue, so please apply the attached.

It does NOT check for rules or on delete triggers (old style foreign
keys) as those are difficult to deal with (remove, truncate, re-add).

Rod Taylor
This commit is contained in:
Bruce Momjian
2002-08-22 04:51:06 +00:00
parent dac22ee43c
commit 47b37a6bfa
5 changed files with 93 additions and 3 deletions
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36
src/backend/commands/tablecmds.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.30 2002/08/19 15:08:46 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.31 2002/08/22 04:51:05 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -332,6 +332,10 @@ TruncateRelation(const RangeVar *relation)
{
Relation rel;
Oid relid;
ScanKeyData key;
Relation fkeyRel;
SysScanDesc fkeyScan;
HeapTuple tuple;
/* Grab exclusive lock in preparation for truncate */
rel = heap_openrv(relation, AccessExclusiveLock);
@@ -356,6 +360,36 @@ TruncateRelation(const RangeVar *relation)
if (!pg_class_ownercheck(relid, GetUserId()))
aclcheck_error(ACLCHECK_NOT_OWNER, RelationGetRelationName(rel));
/*
* Don't allow truncate on tables which are referenced
* by foreign keys
*/
fkeyRel = heap_openr(ConstraintRelationName, AccessShareLock);
ScanKeyEntryInitialize(&key, 0,
Anum_pg_constraint_confrelid,
F_OIDEQ,
ObjectIdGetDatum(relid));
fkeyScan = systable_beginscan(fkeyRel, 0, false,
SnapshotNow, 1, &key);
/*
* First foriegn key found with us as the reference
* should throw an error.
*/
while (HeapTupleIsValid(tuple = systable_getnext(fkeyScan)))
{
Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
if (con->contype == 'f')
elog(ERROR, "TRUNCATE cannot be used as other tables reference this one via foreign key constraint %s",
NameStr(con->conname));
}
systable_endscan(fkeyScan);
heap_close(fkeyRel, AccessShareLock);
/* Keep the lock until transaction commit */
heap_close(rel, NoLock);