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Commitb577a57

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ALTER TABLE ... ALTER CONSTRAINT for FKs
Allow constraint attributes to be altered,so the default setting of NOT DEFERRABLEcan be altered to DEFERRABLE and back.Review by Abhijit Menon-Sen
1 parentce18b01 commitb577a57

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6 files changed

+204
-0
lines changed

6 files changed

+204
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lines changed

‎doc/src/sgml/ref/alter_table.sgml

Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -46,6 +46,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
4646
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
4747
ADD <replaceable class="PARAMETER">table_constraint</replaceable> [ NOT VALID ]
4848
ADD <replaceable class="PARAMETER">table_constraint_using_index</replaceable>
49+
ALTER CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
4950
VALIDATE CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable>
5051
DROP CONSTRAINT [ IF EXISTS ] <replaceable class="PARAMETER">constraint_name</replaceable> [ RESTRICT | CASCADE ]
5152
DISABLE TRIGGER [ <replaceable class="PARAMETER">trigger_name</replaceable> | ALL | USER ]
@@ -316,6 +317,16 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
316317
</listitem>
317318
</varlistentry>
318319

320+
<varlistentry>
321+
<term><literal>ALTER CONSTRAINT</literal></term>
322+
<listitem>
323+
<para>
324+
This form alters the attributes of a constraint that was previously
325+
created. Currently only foreign key constraints may be altered.
326+
</para>
327+
</listitem>
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</varlistentry>
329+
319330
<varlistentry>
320331
<term><literal>VALIDATE CONSTRAINT</literal></term>
321332
<listitem>

‎src/backend/commands/tablecmds.c

Lines changed: 138 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -275,6 +275,8 @@ static void AlterIndexNamespaces(Relation classRel, Relation rel,
275275
staticvoidAlterSeqNamespaces(RelationclassRel,Relationrel,
276276
OidoldNspOid,OidnewNspOid,ObjectAddresses*objsMoved,
277277
LOCKMODElockmode);
278+
staticvoidATExecAlterConstraint(Relationrel,AlterTableCmd*cmd,
279+
boolrecurse,boolrecursing,LOCKMODElockmode);
278280
staticvoidATExecValidateConstraint(Relationrel,char*constrName,
279281
boolrecurse,boolrecursing,LOCKMODElockmode);
280282
staticinttransformColumnNameList(OidrelId,List*colList,
@@ -2886,6 +2888,7 @@ AlterTableGetLockLevel(List *cmds)
28862888
caseAT_SetOptions:
28872889
caseAT_ResetOptions:
28882890
caseAT_SetStorage:
2891+
caseAT_AlterConstraint:
28892892
caseAT_ValidateConstraint:
28902893
cmd_lockmode=ShareUpdateExclusiveLock;
28912894
break;
@@ -3124,6 +3127,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
31243127
ATPrepAddInherit(rel);
31253128
pass=AT_PASS_MISC;
31263129
break;
3130+
caseAT_AlterConstraint:/* ALTER CONSTRAINT */
3131+
ATSimplePermissions(rel,ATT_TABLE);
3132+
break;
31273133
caseAT_ValidateConstraint:/* VALIDATE CONSTRAINT */
31283134
ATSimplePermissions(rel,ATT_TABLE);
31293135
/* Recursion occurs during execution phase */
@@ -3302,6 +3308,9 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
33023308
caseAT_AddIndexConstraint:/* ADD CONSTRAINT USING INDEX */
33033309
ATExecAddIndexConstraint(tab,rel, (IndexStmt*)cmd->def,lockmode);
33043310
break;
3311+
caseAT_AlterConstraint:/* ALTER CONSTRAINT */
3312+
ATExecAlterConstraint(rel,cmd, false, false,lockmode);
3313+
break;
33053314
caseAT_ValidateConstraint:/* VALIDATE CONSTRAINT */
33063315
ATExecValidateConstraint(rel,cmd->name, false, false,lockmode);
33073316
break;
@@ -6173,6 +6182,135 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
61736182
heap_close(pkrel,NoLock);
61746183
}
61756184

6185+
/*
6186+
* ALTER TABLE ALTER CONSTRAINT
6187+
*
6188+
* Update the attributes of a constraint.
6189+
*
6190+
* Currently only works for Foreign Key constraints.
6191+
* Foreign keys do not inherit, so we purposely ignore the
6192+
* recursion bit here, but we keep the API the same for when
6193+
* other constraint types are supported.
6194+
*/
6195+
staticvoid
6196+
ATExecAlterConstraint(Relationrel,AlterTableCmd*cmd,
6197+
boolrecurse,boolrecursing,LOCKMODElockmode)
6198+
{
6199+
Relationconrel;
6200+
SysScanDescscan;
6201+
ScanKeyDatakey;
6202+
HeapTuplecontuple;
6203+
Form_pg_constraintcurrcon=NULL;
6204+
Constraint*cmdcon=NULL;
6205+
boolfound= false;
6206+
6207+
Assert(IsA(cmd->def,Constraint));
6208+
cmdcon= (Constraint*)cmd->def;
6209+
6210+
conrel=heap_open(ConstraintRelationId,RowExclusiveLock);
6211+
6212+
/*
6213+
* Find and check the target constraint
6214+
*/
6215+
ScanKeyInit(&key,
6216+
Anum_pg_constraint_conrelid,
6217+
BTEqualStrategyNumber,F_OIDEQ,
6218+
ObjectIdGetDatum(RelationGetRelid(rel)));
6219+
scan=systable_beginscan(conrel,ConstraintRelidIndexId,
6220+
true,SnapshotNow,1,&key);
6221+
6222+
while (HeapTupleIsValid(contuple=systable_getnext(scan)))
6223+
{
6224+
currcon= (Form_pg_constraint)GETSTRUCT(contuple);
6225+
if (strcmp(NameStr(currcon->conname),cmdcon->conname)==0)
6226+
{
6227+
found= true;
6228+
break;
6229+
}
6230+
}
6231+
6232+
if (!found)
6233+
ereport(ERROR,
6234+
(errcode(ERRCODE_UNDEFINED_OBJECT),
6235+
errmsg("constraint \"%s\" of relation \"%s\" does not exist",
6236+
cmdcon->conname,RelationGetRelationName(rel))));
6237+
6238+
if (currcon->contype!=CONSTRAINT_FOREIGN)
6239+
ereport(ERROR,
6240+
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
6241+
errmsg("constraint \"%s\" of relation \"%s\" is not a foreign key constraint",
6242+
cmdcon->conname,RelationGetRelationName(rel))));
6243+
6244+
if (currcon->condeferrable!=cmdcon->deferrable||
6245+
currcon->condeferred!=cmdcon->initdeferred)
6246+
{
6247+
HeapTuplecopyTuple;
6248+
HeapTupletgtuple;
6249+
Form_pg_constraintcopy_con;
6250+
Form_pg_triggercopy_tg;
6251+
ScanKeyDatatgkey;
6252+
SysScanDesctgscan;
6253+
Relationtgrel;
6254+
6255+
/*
6256+
* Now update the catalog, while we have the door open.
6257+
*/
6258+
copyTuple=heap_copytuple(contuple);
6259+
copy_con= (Form_pg_constraint)GETSTRUCT(copyTuple);
6260+
copy_con->condeferrable=cmdcon->deferrable;
6261+
copy_con->condeferred=cmdcon->initdeferred;
6262+
simple_heap_update(conrel,&copyTuple->t_self,copyTuple);
6263+
CatalogUpdateIndexes(conrel,copyTuple);
6264+
6265+
InvokeObjectPostAlterHook(ConstraintRelationId,
6266+
HeapTupleGetOid(contuple),0);
6267+
6268+
heap_freetuple(copyTuple);
6269+
6270+
/*
6271+
* Now we need to update the multiple entries in pg_trigger
6272+
* that implement the constraint.
6273+
*/
6274+
tgrel=heap_open(TriggerRelationId,RowExclusiveLock);
6275+
6276+
ScanKeyInit(&tgkey,
6277+
Anum_pg_trigger_tgconstraint,
6278+
BTEqualStrategyNumber,F_OIDEQ,
6279+
ObjectIdGetDatum(HeapTupleGetOid(contuple)));
6280+
6281+
tgscan=systable_beginscan(tgrel,TriggerConstraintIndexId, true,
6282+
SnapshotNow,1,&tgkey);
6283+
6284+
while (HeapTupleIsValid(tgtuple=systable_getnext(tgscan)))
6285+
{
6286+
copyTuple=heap_copytuple(tgtuple);
6287+
copy_tg= (Form_pg_trigger)GETSTRUCT(copyTuple);
6288+
copy_tg->tgdeferrable=cmdcon->deferrable;
6289+
copy_tg->tginitdeferred=cmdcon->initdeferred;
6290+
simple_heap_update(tgrel,&copyTuple->t_self,copyTuple);
6291+
CatalogUpdateIndexes(tgrel,copyTuple);
6292+
6293+
InvokeObjectPostAlterHook(TriggerRelationId,
6294+
HeapTupleGetOid(tgtuple),0);
6295+
6296+
heap_freetuple(copyTuple);
6297+
}
6298+
6299+
systable_endscan(tgscan);
6300+
6301+
heap_close(tgrel,RowExclusiveLock);
6302+
6303+
/*
6304+
* Invalidate relcache so that others see the new attributes.
6305+
*/
6306+
CacheInvalidateRelcache(rel);
6307+
}
6308+
6309+
systable_endscan(scan);
6310+
6311+
heap_close(conrel,RowExclusiveLock);
6312+
}
6313+
61766314
/*
61776315
* ALTER TABLE VALIDATE CONSTRAINT
61786316
*

‎src/backend/parser/gram.y

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1941,6 +1941,21 @@ alter_table_cmd:
19411941
n->def =$2;
19421942
$$ = (Node *)n;
19431943
}
1944+
/* ALTER TABLE <name> ALTER CONSTRAINT ...*/
1945+
|ALTERCONSTRAINTnameConstraintAttributeSpec
1946+
{
1947+
AlterTableCmd *n = makeNode(AlterTableCmd);
1948+
Constraint *c = makeNode(Constraint);
1949+
n->subtype = AT_AlterConstraint;
1950+
n->def = (Node *) c;
1951+
c->contype = CONSTR_FOREIGN;/* others not supported, yet*/
1952+
c->conname =$3;
1953+
processCASbits($4, @4,"ALTER CONSTRAINT statement",
1954+
&c->deferrable,
1955+
&c->initdeferred,
1956+
NULL,NULL, yyscanner);
1957+
$$ = (Node *)n;
1958+
}
19441959
/* ALTER TABLE <name> VALIDATE CONSTRAINT ...*/
19451960
|VALIDATECONSTRAINTname
19461961
{

‎src/include/nodes/parsenodes.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1209,6 +1209,7 @@ typedef enum AlterTableType
12091209
AT_AddConstraint,/* add constraint */
12101210
AT_AddConstraintRecurse,/* internal to commands/tablecmds.c */
12111211
AT_ReAddConstraint,/* internal to commands/tablecmds.c */
1212+
AT_AlterConstraint,/* alter constraint */
12121213
AT_ValidateConstraint,/* validate constraint */
12131214
AT_ValidateConstraintRecurse,/* internal to commands/tablecmds.c */
12141215
AT_ProcessedConstraint,/* pre-processed add constraint (local in

‎src/test/regress/expected/foreign_key.out

Lines changed: 19 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1132,6 +1132,15 @@ CREATE TEMP TABLE fktable (
11321132
id int primary key,
11331133
fk int references pktable deferrable initially deferred
11341134
);
1135+
-- check ALTER CONSTRAINT
1136+
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE;
1137+
-- illegal option
1138+
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE INITIALLY DEFERRED;
1139+
ERROR: constraint declared INITIALLY DEFERRED must be DEFERRABLE
1140+
LINE 1: ...e ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE INITIALLY ...
1141+
^
1142+
-- reset
1143+
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY DEFERRED;
11351144
INSERT INTO pktable VALUES (5, 10);
11361145
BEGIN;
11371146
-- doesn't match PK, but no error yet
@@ -1142,6 +1151,16 @@ UPDATE fktable SET id = id + 1;
11421151
COMMIT;
11431152
ERROR: insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
11441153
DETAIL: Key (fk)=(20) is not present in table "pktable".
1154+
-- change the constraint definition and retest
1155+
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY IMMEDIATE;
1156+
BEGIN;
1157+
-- doesn't match PK, should throw error now
1158+
INSERT INTO fktable VALUES (0, 20);
1159+
ERROR: insert or update on table "fktable" violates foreign key constraint "fktable_fk_fkey"
1160+
DETAIL: Key (fk)=(20) is not present in table "pktable".
1161+
COMMIT;
1162+
-- reset
1163+
ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY DEFERRED;
11451164
-- check same case when insert is in a different subtransaction than update
11461165
BEGIN;
11471166
-- doesn't match PK, but no error yet

‎src/test/regress/sql/foreign_key.sql

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -818,6 +818,13 @@ CREATE TEMP TABLE fktable (
818818
fkintreferences pktable deferrable initially deferred
819819
);
820820

821+
-- check ALTER CONSTRAINT
822+
ALTERTABLE fktable ALTERCONSTRAINT fktable_fk_fkey NOT DEFERRABLE;
823+
-- illegal option
824+
ALTERTABLE fktable ALTERCONSTRAINT fktable_fk_fkey NOT DEFERRABLE INITIALLY DEFERRED;
825+
-- reset
826+
ALTERTABLE fktable ALTERCONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY DEFERRED;
827+
821828
INSERT INTO pktableVALUES (5,10);
822829

823830
BEGIN;
@@ -831,6 +838,19 @@ UPDATE fktable SET id = id + 1;
831838
-- should catch error from initial INSERT
832839
COMMIT;
833840

841+
-- change the constraint definition and retest
842+
ALTERTABLE fktable ALTERCONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY IMMEDIATE;
843+
844+
BEGIN;
845+
846+
-- doesn't match PK, should throw error now
847+
INSERT INTO fktableVALUES (0,20);
848+
849+
COMMIT;
850+
851+
-- reset
852+
ALTERTABLE fktable ALTERCONSTRAINT fktable_fk_fkey DEFERRABLE INITIALLY DEFERRED;
853+
834854
-- check same case when insert is in a different subtransaction than update
835855

836856
BEGIN;

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