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Add CASCADE option to TRUNCATE. Joachim Wieland

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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42
doc/src/sgml/ref/truncate.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/truncate.sgml,v 1.19 2005/02/22 19:06:18 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/truncate.sgml,v 1.20 2006/03/03 03:30:52 tgl Exp $
PostgreSQL documentation
-->
@ -20,7 +20,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...]
TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ CASCADE | RESTRICT ]
</synopsis>
</refsynopsisdiv>
@ -47,6 +47,27 @@ TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...]
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically truncate all tables that have foreign-key references
to any of the named tables, or to any tables added to the group
due to <literal>CASCADE</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RESTRICT</literal></term>
<listitem>
<para>
Refuse to truncate if any of the tables have foreign-key references
from tables that are not to be truncated. This is the default.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
@ -61,7 +82,10 @@ TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...]
<command>TRUNCATE</> cannot be used on a table that has foreign-key
references from other tables, unless all such tables are also truncated
in the same command. Checking validity in such cases would require table
scans, and the whole point is not to do one.
scans, and the whole point is not to do one. The <literal>CASCADE</>
option can be used to automatically include all dependent tables &mdash;
but be very careful when using this option, else you might lose data you
did not intend to!
</para>
<para>
@ -78,10 +102,20 @@ TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...]
<programlisting>
TRUNCATE TABLE bigtable, fattable;
</programlisting>
</para>
<para>
Truncate the table <literal>othertable</literal>, and cascade to any tables
that are referencing <literal>othertable</literal> via foreign-key
constraints:
<programlisting>
TRUNCATE othertable CASCADE;
</programlisting>
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>

62
src/backend/catalog/heap.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.293 2005/11/22 18:17:08 momjian Exp $
* $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.294 2006/03/03 03:30:52 tgl Exp $
*
*
* INTERFACE ROUTINES
@ -2043,7 +2043,7 @@ heap_truncate_check_FKs(List *relations, bool tempTables)
if (con->contype != CONSTRAINT_FOREIGN)
continue;
/* Not for one of our list of tables */
/* Not referencing one of our list of tables */
if (!list_member_oid(oids, con->confrelid))
continue;
@ -2066,7 +2066,8 @@ heap_truncate_check_FKs(List *relations, bool tempTables)
get_rel_name(con->conrelid),
get_rel_name(con->confrelid),
NameStr(con->conname)),
errhint("Truncate table \"%s\" at the same time.",
errhint("Truncate table \"%s\" at the same time, "
"or use TRUNCATE ... CASCADE.",
get_rel_name(con->conrelid))));
}
}
@ -2074,3 +2075,58 @@ heap_truncate_check_FKs(List *relations, bool tempTables)
systable_endscan(fkeyScan);
heap_close(fkeyRel, AccessShareLock);
}
/*
* heap_truncate_find_FKs
* Find relations having foreign keys referencing any relations that
* are to be truncated
*
* This is almost the same code as heap_truncate_check_FKs, but we don't
* raise an error if we find such relations; instead we return a list of
* their OIDs. Also note that the input is a list of OIDs not a list
* of Relations. The result list does *not* include any rels that are
* already in the input list.
*
* Note: caller should already have exclusive lock on all rels mentioned
* in relationIds. Since adding or dropping an FK requires exclusive lock
* on both rels, this ensures that the answer will be stable.
*/
List *
heap_truncate_find_FKs(List *relationIds)
{
List *result = NIL;
Relation fkeyRel;
SysScanDesc fkeyScan;
HeapTuple tuple;
/*
* Must scan pg_constraint. Right now, it is a seqscan because
* there is no available index on confrelid.
*/
fkeyRel = heap_open(ConstraintRelationId, AccessShareLock);
fkeyScan = systable_beginscan(fkeyRel, InvalidOid, false,
SnapshotNow, 0, NULL);
while (HeapTupleIsValid(tuple = systable_getnext(fkeyScan)))
{
Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
/* Not a foreign key */
if (con->contype != CONSTRAINT_FOREIGN)
continue;
/* Not referencing one of our list of tables */
if (!list_member_oid(relationIds, con->confrelid))
continue;
/* Add referencer unless already in input or result list */
if (!list_member_oid(relationIds, con->conrelid))
result = list_append_unique_oid(result, con->conrelid);
}
systable_endscan(fkeyScan);
heap_close(fkeyRel, AccessShareLock);
return result;
}

90
src/backend/commands/tablecmds.c
View File

@ -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

3
src/backend/nodes/copyfuncs.c
View File

@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.327 2006/02/19 00:04:26 neilc Exp $
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.328 2006/03/03 03:30:52 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1961,6 +1961,7 @@ _copyTruncateStmt(TruncateStmt *from)
TruncateStmt *newnode = makeNode(TruncateStmt);
COPY_NODE_FIELD(relations);
COPY_SCALAR_FIELD(behavior);
return newnode;
}

3
src/backend/nodes/equalfuncs.c
View File

@ -18,7 +18,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.263 2006/02/19 00:04:26 neilc Exp $
* $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.264 2006/03/03 03:30:52 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -930,6 +930,7 @@ static bool
_equalTruncateStmt(TruncateStmt *a, TruncateStmt *b)
{
COMPARE_NODE_FIELD(relations);
COMPARE_SCALAR_FIELD(behavior);
return true;
}

5
src/backend/parser/gram.y
View File

@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.531 2006/02/28 22:37:26 tgl Exp $
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.532 2006/03/03 03:30:53 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -2938,10 +2938,11 @@ attrs: '.' attr_name
*****************************************************************************/
TruncateStmt:
TRUNCATE opt_table qualified_name_list
TRUNCATE opt_table qualified_name_list opt_drop_behavior
{
TruncateStmt *n = makeNode(TruncateStmt);
n->relations = $3;
n->behavior = $4;
$$ = (Node *)n;
}
;

8
src/backend/tcop/utility.c
View File

@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.252 2006/02/12 19:11:01 momjian Exp $
* $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.253 2006/03/03 03:30:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -628,11 +628,7 @@ ProcessUtility(Node *parsetree,
break;
case T_TruncateStmt:
{
TruncateStmt *stmt = (TruncateStmt *) parsetree;
ExecuteTruncate(stmt->relations);
}
ExecuteTruncate((TruncateStmt *) parsetree);
break;
case T_CommentStmt:

4
src/include/catalog/heap.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/catalog/heap.h,v 1.76 2005/10/15 02:49:42 momjian Exp $
* $PostgreSQL: pgsql/src/include/catalog/heap.h,v 1.77 2006/03/03 03:30:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -62,6 +62,8 @@ extern void heap_truncate(List *relids);
extern void heap_truncate_check_FKs(List *relations, bool tempTables);
extern List *heap_truncate_find_FKs(List *relationIds);
extern List *AddRelationRawConstraints(Relation rel,
List *rawColDefaults,
List *rawConstraints);

4
src/include/commands/tablecmds.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/commands/tablecmds.h,v 1.25 2005/11/21 12:49:32 alvherre Exp $
* $PostgreSQL: pgsql/src/include/commands/tablecmds.h,v 1.26 2006/03/03 03:30:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -36,7 +36,7 @@ extern void AlterRelationNamespaceInternal(Relation classRel, Oid relOid,
Oid oldNspOid, Oid newNspOid,
bool hasDependEntry);
extern void ExecuteTruncate(List *relations);
extern void ExecuteTruncate(TruncateStmt *stmt);
extern void renameatt(Oid myrelid,
const char *oldattname,

3
src/include/nodes/parsenodes.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.301 2006/02/19 00:04:27 neilc Exp $
* $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.302 2006/03/03 03:30:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1314,6 +1314,7 @@ typedef struct TruncateStmt
{
NodeTag type;
List *relations; /* relations (RangeVars) to be truncated */
DropBehavior behavior; /* RESTRICT or CASCADE behavior */
} TruncateStmt;
/* ----------------------

54
src/test/regress/expected/truncate.out
View File

@ -40,30 +40,37 @@ CREATE TABLE trunc_e (a int REFERENCES truncate_a, b int REFERENCES trunc_c);
TRUNCATE TABLE truncate_a; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
HINT: Truncate table "trunc_b" at the same time.
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE truncate_a,trunc_b; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "trunc_e" references "truncate_a" via foreign key constraint "trunc_e_a_fkey".
HINT: Truncate table "trunc_e" at the same time.
HINT: Truncate table "trunc_e" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE truncate_a,trunc_b,trunc_e; -- ok
TRUNCATE TABLE truncate_a,trunc_e; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
HINT: Truncate table "trunc_b" at the same time.
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "trunc_d" references "trunc_c" via foreign key constraint "trunc_d_a_fkey".
HINT: Truncate table "trunc_d" at the same time.
HINT: Truncate table "trunc_d" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c,trunc_d; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "trunc_e" references "trunc_c" via foreign key constraint "trunc_e_b_fkey".
HINT: Truncate table "trunc_e" at the same time.
HINT: Truncate table "trunc_e" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c,trunc_d,trunc_e; -- ok
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
HINT: Truncate table "trunc_b" at the same time.
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a,trunc_b; -- ok
TRUNCATE TABLE truncate_a RESTRICT; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE truncate_a CASCADE; -- ok
NOTICE: truncate cascades to table "trunc_b"
NOTICE: truncate cascades to table "trunc_e"
-- circular references
ALTER TABLE truncate_a ADD FOREIGN KEY (col1) REFERENCES trunc_c;
-- Add some data to verify that truncating actually works ...
@ -75,19 +82,19 @@ INSERT INTO trunc_e VALUES (1,1);
TRUNCATE TABLE trunc_c;
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "trunc_d" references "trunc_c" via foreign key constraint "trunc_d_a_fkey".
HINT: Truncate table "trunc_d" at the same time.
HINT: Truncate table "trunc_d" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c,trunc_d;
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "trunc_e" references "trunc_c" via foreign key constraint "trunc_e_b_fkey".
HINT: Truncate table "trunc_e" at the same time.
HINT: Truncate table "trunc_e" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c,trunc_d,trunc_e;
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "truncate_a" references "trunc_c" via foreign key constraint "truncate_a_col1_fkey".
HINT: Truncate table "truncate_a" at the same time.
HINT: Truncate table "truncate_a" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a;
ERROR: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
HINT: Truncate table "trunc_b" at the same time.
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a,trunc_b;
-- Verify that truncating did actually work
SELECT * FROM truncate_a
@ -106,6 +113,33 @@ SELECT * FROM trunc_e;
---+---
(0 rows)
-- Add data again to test TRUNCATE ... CASCADE
INSERT INTO trunc_c VALUES (1);
INSERT INTO truncate_a VALUES (1);
INSERT INTO trunc_b VALUES (1);
INSERT INTO trunc_d VALUES (1);
INSERT INTO trunc_e VALUES (1,1);
TRUNCATE TABLE trunc_c CASCADE; -- ok
NOTICE: truncate cascades to table "trunc_d"
NOTICE: truncate cascades to table "trunc_e"
NOTICE: truncate cascades to table "truncate_a"
NOTICE: truncate cascades to table "trunc_b"
SELECT * FROM truncate_a
UNION ALL
SELECT * FROM trunc_c
UNION ALL
SELECT * FROM trunc_b
UNION ALL
SELECT * FROM trunc_d;
col1
------
(0 rows)
SELECT * FROM trunc_e;
a | b
---+---
(0 rows)
DROP TABLE truncate_a,trunc_c,trunc_b,trunc_d,trunc_e CASCADE;
NOTICE: drop cascades to constraint trunc_e_a_fkey on table trunc_e
NOTICE: drop cascades to constraint trunc_b_a_fkey on table trunc_b

21
src/test/regress/sql/truncate.sql
View File

@ -30,6 +30,9 @@ TRUNCATE TABLE trunc_c,trunc_d,trunc_e; -- ok
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a; -- fail
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a,trunc_b; -- ok
TRUNCATE TABLE truncate_a RESTRICT; -- fail
TRUNCATE TABLE truncate_a CASCADE; -- ok
-- circular references
ALTER TABLE truncate_a ADD FOREIGN KEY (col1) REFERENCES trunc_c;
@ -55,4 +58,22 @@ SELECT * FROM truncate_a
SELECT * FROM trunc_d;
SELECT * FROM trunc_e;
-- Add data again to test TRUNCATE ... CASCADE
INSERT INTO trunc_c VALUES (1);
INSERT INTO truncate_a VALUES (1);
INSERT INTO trunc_b VALUES (1);
INSERT INTO trunc_d VALUES (1);
INSERT INTO trunc_e VALUES (1,1);
TRUNCATE TABLE trunc_c CASCADE; -- ok
SELECT * FROM truncate_a
UNION ALL
SELECT * FROM trunc_c
UNION ALL
SELECT * FROM trunc_b
UNION ALL
SELECT * FROM trunc_d;
SELECT * FROM trunc_e;
DROP TABLE truncate_a,trunc_c,trunc_b,trunc_d,trunc_e CASCADE;