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ALTER TABLE ... ALTER CONSTRAINT for FKs

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Allow constraint attributes to be altered,
so the default setting of NOT DEFERRABLE
can be altered to DEFERRABLE and back.

Review by Abhijit Menon-Sen
pull/6/head
Simon Riggs 12 years ago
parent 2f74e4ec50
commit f177cbfe67
6 changed files with 205 additions and 0 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 11
      doc/src/sgml/ref/alter_table.sgml
  2. 139
      src/backend/commands/tablecmds.c
  3. 15
      src/backend/parser/gram.y
  4. 1
      src/include/nodes/parsenodes.h
  5. 19
      src/test/regress/expected/foreign_key.out
  6. 20
      src/test/regress/sql/foreign_key.sql

11
doc/src/sgml/ref/alter_table.sgml
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@ -46,6 +46,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
ADD <replaceable class="PARAMETER">table_constraint</replaceable> [ NOT VALID ]
ADD <replaceable class="PARAMETER">table_constraint_using_index</replaceable>
ALTER CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
VALIDATE CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable>
DROP CONSTRAINT [ IF EXISTS ] <replaceable class="PARAMETER">constraint_name</replaceable> [ RESTRICT | CASCADE ]
DISABLE TRIGGER [ <replaceable class="PARAMETER">trigger_name</replaceable> | ALL | USER ]
@ -316,6 +317,16 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ALTER CONSTRAINT</literal></term>
<listitem>
<para>
This form alters the attributes of a constraint that was previously
created. Currently only foreign key constraints may be altered.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>VALIDATE CONSTRAINT</literal></term>
<listitem>

139
src/backend/commands/tablecmds.c
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@ -276,6 +276,8 @@ static void AlterIndexNamespaces(Relation classRel, Relation rel,
static void AlterSeqNamespaces(Relation classRel, Relation rel,
Oid oldNspOid, Oid newNspOid, ObjectAddresses *objsMoved,
LOCKMODE lockmode);
static void ATExecAlterConstraint(Relation rel, AlterTableCmd *cmd,
bool recurse, bool recursing, LOCKMODE lockmode);
static void ATExecValidateConstraint(Relation rel, char *constrName,
bool recurse, bool recursing, LOCKMODE lockmode);
static int transformColumnNameList(Oid relId, List *colList,
@ -2887,6 +2889,7 @@ AlterTableGetLockLevel(List *cmds)
case AT_SetOptions:
case AT_ResetOptions:
case AT_SetStorage:
case AT_AlterConstraint:
case AT_ValidateConstraint:
cmd_lockmode = ShareUpdateExclusiveLock;
break;
@ -3125,6 +3128,10 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
ATPrepAddInherit(rel);
pass = AT_PASS_MISC;
break;
case AT_AlterConstraint: /* ALTER CONSTRAINT */
ATSimplePermissions(rel, ATT_TABLE);
pass = AT_PASS_MISC;
break;
case AT_ValidateConstraint: /* VALIDATE CONSTRAINT */
ATSimplePermissions(rel, ATT_TABLE);
/* Recursion occurs during execution phase */
@ -3304,6 +3311,9 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
case AT_AddIndexConstraint: /* ADD CONSTRAINT USING INDEX */
ATExecAddIndexConstraint(tab, rel, (IndexStmt *) cmd->def, lockmode);
break;
case AT_AlterConstraint: /* ALTER CONSTRAINT */
ATExecAlterConstraint(rel, cmd, false, false, lockmode);
break;
case AT_ValidateConstraint: /* VALIDATE CONSTRAINT */
ATExecValidateConstraint(rel, cmd->name, false, false, lockmode);
break;
@ -6175,6 +6185,135 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
heap_close(pkrel, NoLock);
}
/*
* ALTER TABLE ALTER CONSTRAINT
*
* Update the attributes of a constraint.
*
* Currently only works for Foreign Key constraints.
* Foreign keys do not inherit, so we purposely ignore the
* recursion bit here, but we keep the API the same for when
* other constraint types are supported.
*/
static void
ATExecAlterConstraint(Relation rel, AlterTableCmd *cmd,
bool recurse, bool recursing, LOCKMODE lockmode)
{
Relation conrel;
SysScanDesc scan;
ScanKeyData key;
HeapTuple contuple;
Form_pg_constraint currcon = NULL;
Constraint *cmdcon = NULL;
bool found = false;
Assert(IsA(cmd->def, Constraint));
cmdcon = (Constraint *) cmd->def;
conrel = heap_open(ConstraintRelationId, RowExclusiveLock);
/*
* Find and check the target constraint
*/
ScanKeyInit(&key,
Anum_pg_constraint_conrelid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
scan = systable_beginscan(conrel, ConstraintRelidIndexId,
true, SnapshotNow, 1, &key);
while (HeapTupleIsValid(contuple = systable_getnext(scan)))
{
currcon = (Form_pg_constraint) GETSTRUCT(contuple);
if (strcmp(NameStr(currcon->conname), cmdcon->conname) == 0)
{
found = true;
break;
}
}
if (!found)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("constraint \"%s\" of relation \"%s\" does not exist",
cmdcon->conname, RelationGetRelationName(rel))));
if (currcon->contype != CONSTRAINT_FOREIGN)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("constraint \"%s\" of relation \"%s\" is not a foreign key constraint",
cmdcon->conname, RelationGetRelationName(rel))));
if (currcon->condeferrable != cmdcon->deferrable ||
currcon->condeferred != cmdcon->initdeferred)
{
HeapTuple copyTuple;
HeapTuple tgtuple;
Form_pg_constraint copy_con;
Form_pg_trigger copy_tg;
ScanKeyData tgkey;
SysScanDesc tgscan;
Relation tgrel;
/*
* Now update the catalog, while we have the door open.
*/
copyTuple = heap_copytuple(contuple);
copy_con = (Form_pg_constraint) GETSTRUCT(copyTuple);
copy_con->condeferrable = cmdcon->deferrable;
copy_con->condeferred = cmdcon->initdeferred;
simple_heap_update(conrel, &copyTuple->t_self, copyTuple);
CatalogUpdateIndexes(conrel, copyTuple);
InvokeObjectPostAlterHook(ConstraintRelationId,
HeapTupleGetOid(contuple), 0);
heap_freetuple(copyTuple);
/*
* Now we need to update the multiple entries in pg_trigger
* that implement the constraint.
*/
tgrel = heap_open(TriggerRelationId, RowExclusiveLock);
ScanKeyInit(&tgkey,
Anum_pg_trigger_tgconstraint,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(HeapTupleGetOid(contuple)));
tgscan = systable_beginscan(tgrel, TriggerConstraintIndexId, true,
SnapshotNow, 1, &tgkey);
while (HeapTupleIsValid(tgtuple = systable_getnext(tgscan)))
{
copyTuple = heap_copytuple(tgtuple);
copy_tg = (Form_pg_trigger) GETSTRUCT(copyTuple);
copy_tg->tgdeferrable = cmdcon->deferrable;
copy_tg->tginitdeferred = cmdcon->initdeferred;
simple_heap_update(tgrel, &copyTuple->t_self, copyTuple);
CatalogUpdateIndexes(tgrel, copyTuple);
InvokeObjectPostAlterHook(TriggerRelationId,
HeapTupleGetOid(tgtuple), 0);
heap_freetuple(copyTuple);
}
systable_endscan(tgscan);
heap_close(tgrel, RowExclusiveLock);
/*
* Invalidate relcache so that others see the new attributes.
*/
CacheInvalidateRelcache(rel);
}
systable_endscan(scan);
heap_close(conrel, RowExclusiveLock);
}
/*
* ALTER TABLE VALIDATE CONSTRAINT
*

15
src/backend/parser/gram.y
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@ -1943,6 +1943,21 @@ alter_table_cmd:
n->def = $2;
$$ = (Node *)n;
}
/* ALTER TABLE <name> ALTER CONSTRAINT ... */
| ALTER CONSTRAINT name ConstraintAttributeSpec
{
AlterTableCmd *n = makeNode(AlterTableCmd);
Constraint *c = makeNode(Constraint);
n->subtype = AT_AlterConstraint;
n->def = (Node *) c;
c->contype = CONSTR_FOREIGN; /* others not supported, yet */
c->conname = $3;
processCASbits($4, @4, "ALTER CONSTRAINT statement",
&c->deferrable,
&c->initdeferred,
NULL, NULL, yyscanner);
$$ = (Node *)n;
}
/* ALTER TABLE <name> VALIDATE CONSTRAINT ... */
| VALIDATE CONSTRAINT name
{

1
src/include/nodes/parsenodes.h
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@ -1209,6 +1209,7 @@ typedef enum AlterTableType
AT_AddConstraint, /* add constraint */
AT_AddConstraintRecurse, /* internal to commands/tablecmds.c */
AT_ReAddConstraint, /* internal to commands/tablecmds.c */
AT_AlterConstraint, /* alter constraint */
AT_ValidateConstraint, /* validate constraint */
AT_ValidateConstraintRecurse, /* internal to commands/tablecmds.c */
AT_ProcessedConstraint, /* pre-processed add constraint (local in

19
src/test/regress/expected/foreign_key.out
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@ -1132,6 +1132,15 @@ CREATE TEMP TABLE fktable (
id int primary key,
fk int references pktable deferrable initially deferred
);
-- check ALTER CONSTRAINT
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE;
-- illegal option
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE INITIALLY DEFERRED;
ERROR: constraint declared INITIALLY DEFERRED must be DEFERRABLE
LINE 1: ...e ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE INITIALLY ...
^
-- reset
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY DEFERRED;
INSERT INTO pktable VALUES (5, 10);
BEGIN;
-- doesn't match PK, but no error yet
@ -1142,6 +1151,16 @@ UPDATE fktable SET id = id + 1;
COMMIT;
ERROR: insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
DETAIL: Key (fk)=(20) is not present in table "pktable".
-- change the constraint definition and retest
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY IMMEDIATE;
BEGIN;
-- doesn't match PK, should throw error now
INSERT INTO fktable VALUES (0, 20);
ERROR: insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
DETAIL: Key (fk)=(20) is not present in table "pktable".
COMMIT;
-- reset
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY DEFERRED;
-- check same case when insert is in a different subtransaction than update
BEGIN;
-- doesn't match PK, but no error yet

20
src/test/regress/sql/foreign_key.sql
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@ -818,6 +818,13 @@ CREATE TEMP TABLE fktable (
fk int references pktable deferrable initially deferred
);
-- check ALTER CONSTRAINT
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE;
-- illegal option
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE INITIALLY DEFERRED;
-- reset
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY DEFERRED;
INSERT INTO pktable VALUES (5, 10);
BEGIN;
@ -831,6 +838,19 @@ UPDATE fktable SET id = id + 1;
-- should catch error from initial INSERT
COMMIT;
-- change the constraint definition and retest
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY IMMEDIATE;
BEGIN;
-- doesn't match PK, should throw error now
INSERT INTO fktable VALUES (0, 20);
COMMIT;
-- reset
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY DEFERRED;
-- check same case when insert is in a different subtransaction than update
BEGIN;

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