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Remove arbitrary ALTER TABLE .. ADD COLUMN restriction.

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The previous coding prevented ALTER TABLE .. ADD COLUMN from being used
with a non-NULL default in situations where the table's rowtype was being
used elsewhere.  But this is a completely arbitrary restriction since
you could do the same operation in multiple steps (add the column, add
the default, update the table).

Inspired by a patch from Noah Misch, though I didn't use his code.
This commit is contained in:
Robert Haas
2011-01-26 06:23:23 -05:00
parent 64bc872761
commit a06e41deeb
3 changed files with 17 additions and 8 deletions
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8
src/backend/commands/tablecmds.c
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@ -142,6 +142,7 @@ typedef struct AlteredTableInfo
List *newvals; /* List of NewColumnValue */
bool new_notnull; /* T if we added new NOT NULL constraints */
bool new_changeoids; /* T if we added/dropped the OID column */
bool new_changetypes; /* T if we changed column types */
Oid newTableSpace; /* new tablespace; 0 means no change */
/* Objects to rebuild after completing ALTER TYPE operations */
List *changedConstraintOids; /* OIDs of constraints to rebuild */
@ -3378,14 +3379,14 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
}
/*
* If we need to rewrite the table, the operation has to be propagated to
* tables that use this table's rowtype as a column type.
* If we change column data types or add/remove OIDs, the operation has to
* be propagated to tables that use this table's rowtype as a column type.
*
* (Eventually this will probably become true for scans as well, but at
* the moment a composite type does not enforce any constraints, so it's
* not necessary/appropriate to enforce them just during ALTER.)
*/
if (newrel)
if (tab->new_changetypes || tab->new_changeoids)
find_composite_type_dependencies(oldrel->rd_rel->reltype,
RelationGetRelationName(oldrel),
NULL);
@ -6429,6 +6430,7 @@ ATPrepAlterColumnType(List **wqueue,
newval->expr = (Expr *) transform;
tab->newvals = lappend(tab->newvals, newval);
tab->new_changetypes = true;
}
else if (tab->relkind == RELKIND_FOREIGN_TABLE)
{