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Commita06e41d

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Remove arbitrary ALTER TABLE .. ADD COLUMN restriction.
The previous coding prevented ALTER TABLE .. ADD COLUMN from being usedwith a non-NULL default in situations where the table's rowtype was beingused elsewhere. But this is a completely arbitrary restriction sinceyou could do the same operation in multiple steps (add the column, addthe default, update the table).Inspired by a patch from Noah Misch, though I didn't use his code.
1 parent64bc872 commita06e41d

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3 files changed

+17
-8
lines changed

3 files changed

+17
-8
lines changed

‎src/backend/commands/tablecmds.c

Lines changed: 5 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -142,6 +142,7 @@ typedef struct AlteredTableInfo
142142
List*newvals;/* List of NewColumnValue */
143143
boolnew_notnull;/* T if we added new NOT NULL constraints */
144144
boolnew_changeoids;/* T if we added/dropped the OID column */
145+
boolnew_changetypes;/* T if we changed column types */
145146
OidnewTableSpace;/* new tablespace; 0 means no change */
146147
/* Objects to rebuild after completing ALTER TYPE operations */
147148
List*changedConstraintOids;/* OIDs of constraints to rebuild */
@@ -3378,14 +3379,14 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
33783379
}
33793380

33803381
/*
3381-
* If weneed to rewrite the table, the operation has to be propagated to
3382-
* tables that use this table's rowtype as a column type.
3382+
* If wechange column data types or add/remove OIDs, the operation has to
3383+
*be propagated totables that use this table's rowtype as a column type.
33833384
*
33843385
* (Eventually this will probably become true for scans as well, but at
33853386
* the moment a composite type does not enforce any constraints, so it's
33863387
* not necessary/appropriate to enforce them just during ALTER.)
33873388
*/
3388-
if (newrel)
3389+
if (tab->new_changetypes||tab->new_changeoids)
33893390
find_composite_type_dependencies(oldrel->rd_rel->reltype,
33903391
RelationGetRelationName(oldrel),
33913392
NULL);
@@ -6429,6 +6430,7 @@ ATPrepAlterColumnType(List **wqueue,
64296430
newval->expr= (Expr*)transform;
64306431

64316432
tab->newvals=lappend(tab->newvals,newval);
6433+
tab->new_changetypes= true;
64326434
}
64336435
elseif (tab->relkind==RELKIND_FOREIGN_TABLE)
64346436
{

‎src/test/regress/expected/rowtypes.out

Lines changed: 6 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -82,11 +82,14 @@ select * from people;
8282
(Joe,Blow) | 01-10-1984
8383
(1 row)
8484

85-
--atthemoment this will not work due toALTER TABLE inadequacy:
85+
-- thedefault doesn't need to propagate through tothe rowtypes, so this is OK
8686
alter table fullname add column suffix text default '';
87-
ERROR: cannotalter table"fullname" because column"people"."fn" uses its rowtype
88-
--butthisshould work:
87+
alter table fullname drop columnsuffix;
88+
-- thisone, without a default, is OK too
8989
alter table fullname add column suffix text default null;
90+
-- but this should fail, due to ALTER TABLE inadequacy
91+
alter table fullname alter column suffix set data type integer using null;
92+
ERROR: cannot alter table "fullname" because column "people"."fn" uses its rowtype
9093
select * from people;
9194
fn | bd
9295
-------------+------------

‎src/test/regress/sql/rowtypes.sql

Lines changed: 6 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -45,12 +45,16 @@ insert into people values ('(Joe,Blow)', '1984-01-10');
4545

4646
select*from people;
4747

48-
--atthemoment this will not work due toALTER TABLE inadequacy:
48+
-- thedefault doesn't need to propagate through tothe rowtypes, so this is OK
4949
altertable fullname add column suffixtext default'';
50+
altertable fullname drop column suffix;
5051

51-
--butthisshould work:
52+
-- thisone, without a default, is OK too
5253
altertable fullname add column suffixtext defaultnull;
5354

55+
-- but this should fail, due to ALTER TABLE inadequacy
56+
altertable fullname alter column suffixset data typeinteger usingnull;
57+
5458
select*from people;
5559

5660
-- test insertion/updating of subfields

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