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Commitf177cbf

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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 parent2f74e4e commitf177cbf

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6 files changed

+205
-0
lines changed

6 files changed

+205
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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>
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<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.
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</para>
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</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: 139 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -276,6 +276,8 @@ static void AlterIndexNamespaces(Relation classRel, Relation rel,
276276
staticvoidAlterSeqNamespaces(RelationclassRel,Relationrel,
277277
OidoldNspOid,OidnewNspOid,ObjectAddresses*objsMoved,
278278
LOCKMODElockmode);
279+
staticvoidATExecAlterConstraint(Relationrel,AlterTableCmd*cmd,
280+
boolrecurse,boolrecursing,LOCKMODElockmode);
279281
staticvoidATExecValidateConstraint(Relationrel,char*constrName,
280282
boolrecurse,boolrecursing,LOCKMODElockmode);
281283
staticinttransformColumnNameList(OidrelId,List*colList,
@@ -2887,6 +2889,7 @@ AlterTableGetLockLevel(List *cmds)
28872889
caseAT_SetOptions:
28882890
caseAT_ResetOptions:
28892891
caseAT_SetStorage:
2892+
caseAT_AlterConstraint:
28902893
caseAT_ValidateConstraint:
28912894
cmd_lockmode=ShareUpdateExclusiveLock;
28922895
break;
@@ -3125,6 +3128,10 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
31253128
ATPrepAddInherit(rel);
31263129
pass=AT_PASS_MISC;
31273130
break;
3131+
caseAT_AlterConstraint:/* ALTER CONSTRAINT */
3132+
ATSimplePermissions(rel,ATT_TABLE);
3133+
pass=AT_PASS_MISC;
3134+
break;
31283135
caseAT_ValidateConstraint:/* VALIDATE CONSTRAINT */
31293136
ATSimplePermissions(rel,ATT_TABLE);
31303137
/* Recursion occurs during execution phase */
@@ -3304,6 +3311,9 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
33043311
caseAT_AddIndexConstraint:/* ADD CONSTRAINT USING INDEX */
33053312
ATExecAddIndexConstraint(tab,rel, (IndexStmt*)cmd->def,lockmode);
33063313
break;
3314+
caseAT_AlterConstraint:/* ALTER CONSTRAINT */
3315+
ATExecAlterConstraint(rel,cmd, false, false,lockmode);
3316+
break;
33073317
caseAT_ValidateConstraint:/* VALIDATE CONSTRAINT */
33083318
ATExecValidateConstraint(rel,cmd->name, false, false,lockmode);
33093319
break;
@@ -6175,6 +6185,135 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
61756185
heap_close(pkrel,NoLock);
61766186
}
61776187

6188+
/*
6189+
* ALTER TABLE ALTER CONSTRAINT
6190+
*
6191+
* Update the attributes of a constraint.
6192+
*
6193+
* Currently only works for Foreign Key constraints.
6194+
* Foreign keys do not inherit, so we purposely ignore the
6195+
* recursion bit here, but we keep the API the same for when
6196+
* other constraint types are supported.
6197+
*/
6198+
staticvoid
6199+
ATExecAlterConstraint(Relationrel,AlterTableCmd*cmd,
6200+
boolrecurse,boolrecursing,LOCKMODElockmode)
6201+
{
6202+
Relationconrel;
6203+
SysScanDescscan;
6204+
ScanKeyDatakey;
6205+
HeapTuplecontuple;
6206+
Form_pg_constraintcurrcon=NULL;
6207+
Constraint*cmdcon=NULL;
6208+
boolfound= false;
6209+
6210+
Assert(IsA(cmd->def,Constraint));
6211+
cmdcon= (Constraint*)cmd->def;
6212+
6213+
conrel=heap_open(ConstraintRelationId,RowExclusiveLock);
6214+
6215+
/*
6216+
* Find and check the target constraint
6217+
*/
6218+
ScanKeyInit(&key,
6219+
Anum_pg_constraint_conrelid,
6220+
BTEqualStrategyNumber,F_OIDEQ,
6221+
ObjectIdGetDatum(RelationGetRelid(rel)));
6222+
scan=systable_beginscan(conrel,ConstraintRelidIndexId,
6223+
true,SnapshotNow,1,&key);
6224+
6225+
while (HeapTupleIsValid(contuple=systable_getnext(scan)))
6226+
{
6227+
currcon= (Form_pg_constraint)GETSTRUCT(contuple);
6228+
if (strcmp(NameStr(currcon->conname),cmdcon->conname)==0)
6229+
{
6230+
found= true;
6231+
break;
6232+
}
6233+
}
6234+
6235+
if (!found)
6236+
ereport(ERROR,
6237+
(errcode(ERRCODE_UNDEFINED_OBJECT),
6238+
errmsg("constraint \"%s\" of relation \"%s\" does not exist",
6239+
cmdcon->conname,RelationGetRelationName(rel))));
6240+
6241+
if (currcon->contype!=CONSTRAINT_FOREIGN)
6242+
ereport(ERROR,
6243+
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
6244+
errmsg("constraint \"%s\" of relation \"%s\" is not a foreign key constraint",
6245+
cmdcon->conname,RelationGetRelationName(rel))));
6246+
6247+
if (currcon->condeferrable!=cmdcon->deferrable||
6248+
currcon->condeferred!=cmdcon->initdeferred)
6249+
{
6250+
HeapTuplecopyTuple;
6251+
HeapTupletgtuple;
6252+
Form_pg_constraintcopy_con;
6253+
Form_pg_triggercopy_tg;
6254+
ScanKeyDatatgkey;
6255+
SysScanDesctgscan;
6256+
Relationtgrel;
6257+
6258+
/*
6259+
* Now update the catalog, while we have the door open.
6260+
*/
6261+
copyTuple=heap_copytuple(contuple);
6262+
copy_con= (Form_pg_constraint)GETSTRUCT(copyTuple);
6263+
copy_con->condeferrable=cmdcon->deferrable;
6264+
copy_con->condeferred=cmdcon->initdeferred;
6265+
simple_heap_update(conrel,&copyTuple->t_self,copyTuple);
6266+
CatalogUpdateIndexes(conrel,copyTuple);
6267+
6268+
InvokeObjectPostAlterHook(ConstraintRelationId,
6269+
HeapTupleGetOid(contuple),0);
6270+
6271+
heap_freetuple(copyTuple);
6272+
6273+
/*
6274+
* Now we need to update the multiple entries in pg_trigger
6275+
* that implement the constraint.
6276+
*/
6277+
tgrel=heap_open(TriggerRelationId,RowExclusiveLock);
6278+
6279+
ScanKeyInit(&tgkey,
6280+
Anum_pg_trigger_tgconstraint,
6281+
BTEqualStrategyNumber,F_OIDEQ,
6282+
ObjectIdGetDatum(HeapTupleGetOid(contuple)));
6283+
6284+
tgscan=systable_beginscan(tgrel,TriggerConstraintIndexId, true,
6285+
SnapshotNow,1,&tgkey);
6286+
6287+
while (HeapTupleIsValid(tgtuple=systable_getnext(tgscan)))
6288+
{
6289+
copyTuple=heap_copytuple(tgtuple);
6290+
copy_tg= (Form_pg_trigger)GETSTRUCT(copyTuple);
6291+
copy_tg->tgdeferrable=cmdcon->deferrable;
6292+
copy_tg->tginitdeferred=cmdcon->initdeferred;
6293+
simple_heap_update(tgrel,&copyTuple->t_self,copyTuple);
6294+
CatalogUpdateIndexes(tgrel,copyTuple);
6295+
6296+
InvokeObjectPostAlterHook(TriggerRelationId,
6297+
HeapTupleGetOid(tgtuple),0);
6298+
6299+
heap_freetuple(copyTuple);
6300+
}
6301+
6302+
systable_endscan(tgscan);
6303+
6304+
heap_close(tgrel,RowExclusiveLock);
6305+
6306+
/*
6307+
* Invalidate relcache so that others see the new attributes.
6308+
*/
6309+
CacheInvalidateRelcache(rel);
6310+
}
6311+
6312+
systable_endscan(scan);
6313+
6314+
heap_close(conrel,RowExclusiveLock);
6315+
}
6316+
61786317
/*
61796318
* ALTER TABLE VALIDATE CONSTRAINT
61806319
*

‎src/backend/parser/gram.y

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1943,6 +1943,21 @@ alter_table_cmd:
19431943
n->def =$2;
19441944
$$ = (Node *)n;
19451945
}
1946+
/* ALTER TABLE <name> ALTER CONSTRAINT ...*/
1947+
|ALTERCONSTRAINTnameConstraintAttributeSpec
1948+
{
1949+
AlterTableCmd *n = makeNode(AlterTableCmd);
1950+
Constraint *c = makeNode(Constraint);
1951+
n->subtype = AT_AlterConstraint;
1952+
n->def = (Node *) c;
1953+
c->contype = CONSTR_FOREIGN;/* others not supported, yet*/
1954+
c->conname =$3;
1955+
processCASbits($4, @4,"ALTER CONSTRAINT statement",
1956+
&c->deferrable,
1957+
&c->initdeferred,
1958+
NULL,NULL, yyscanner);
1959+
$$ = (Node *)n;
1960+
}
19461961
/* ALTER TABLE <name> VALIDATE CONSTRAINT ...*/
19471962
|VALIDATECONSTRAINTname
19481963
{

‎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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