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Add CASCADE option to TRUNCATE. Joachim Wieland

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This commit is contained in:
Tom Lane
2006-03-03 03:30:54 +00:00
parent 2a0ba3f8dd
commit 984a6ced3e
12 changed files with 252 additions and 47 deletions
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90
src/backend/commands/tablecmds.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.177 2006/01/30 16:18:58 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.178 2006/03/03 03:30:52 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -527,26 +527,79 @@ RemoveRelation(const RangeVar *relation, DropBehavior behavior)
* ExecuteTruncate
* Executes a TRUNCATE command.
*
* This is a multi-relation truncate. It first opens and grabs exclusive
* locks on all relations involved, checking permissions and otherwise
* verifying that the relation is OK for truncation. When they are all
* open, it checks foreign key references on them, namely that FK references
* are all internal to the group that's being truncated. Finally all
* relations are truncated and reindexed.
* This is a multi-relation truncate. We first open and grab exclusive
* lock on all relations involved, checking permissions and otherwise
* verifying that the relation is OK for truncation. In CASCADE mode,
* relations having FK references to the targeted relations are automatically
* added to the group; in RESTRICT mode, we check that all FK references are
* internal to the group that's being truncated. Finally all the relations
* are truncated and reindexed.
*/
void
ExecuteTruncate(List *relations)
ExecuteTruncate(TruncateStmt *stmt)
{
List *rels = NIL;
List *directRelids = NIL;
ListCell *cell;
Oid relid;
Relation rel;
foreach(cell, relations)
/*
* Open and exclusive-lock all the explicitly-specified relations
*/
foreach(cell, stmt->relations)
{
RangeVar *rv = lfirst(cell);
Relation rel;
/* Grab exclusive lock in preparation for truncate */
rel = heap_openrv(rv, AccessExclusiveLock);
rels = lappend(rels, rel);
directRelids = lappend_oid(directRelids, RelationGetRelid(rel));
}
/*
* In CASCADE mode, suck in all referencing relations as well. This
* requires multiple iterations to find indirectly-dependent relations.
* At each phase, we need to exclusive-lock new rels before looking
* for their dependencies, else we might miss something.
*/
if (stmt->behavior == DROP_CASCADE)
{
List *relids = list_copy(directRelids);
for (;;)
{
List *newrelids;
newrelids = heap_truncate_find_FKs(relids);
if (newrelids == NIL)
break; /* nothing else to add */
foreach(cell, newrelids)
{
relid = lfirst_oid(cell);
rel = heap_open(relid, AccessExclusiveLock);
rels = lappend(rels, rel);
relids = lappend_oid(relids, relid);
}
}
}
/* now check all involved relations */
foreach(cell, rels)
{
rel = (Relation) lfirst(cell);
relid = RelationGetRelid(rel);
/*
* If this table was added to the command by CASCADE, report it.
* We don't do this earlier because if we error out on one of the
* tables, it'd be confusing to list subsequently-added tables.
*/
if (stmt->behavior == DROP_CASCADE &&
!list_member_oid(directRelids, relid))
ereport(NOTICE,
(errmsg("truncate cascades to table \"%s\"",
RelationGetRelationName(rel))));
/* Only allow truncate on regular tables */
if (rel->rd_rel->relkind != RELKIND_RELATION)
@ -585,25 +638,30 @@ ExecuteTruncate(List *relations)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot truncate temporary tables of other sessions")));
/* Save it into the list of rels to truncate */
rels = lappend(rels, rel);
}
/*
* Check foreign key references.
* Check foreign key references. In CASCADE mode, this should be
* unnecessary since we just pulled in all the references; but as
* a cross-check, do it anyway if in an Assert-enabled build.
*/
#ifdef USE_ASSERT_CHECKING
heap_truncate_check_FKs(rels, false);
#else
if (stmt->behavior == DROP_RESTRICT)
heap_truncate_check_FKs(rels, false);
#endif
/*
* OK, truncate each table.
*/
foreach(cell, rels)
{
Relation rel = lfirst(cell);
Oid heap_relid;
Oid toast_relid;
rel = (Relation) lfirst(cell);
/*
* Create a new empty storage file for the relation, and assign it as
* the relfilenode value. The old storage file is scheduled for