Re: Information Schema and constraint names not unique

Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> writes:
> On Thu, Nov 06, 2003 at 11:42:13AM -0500, Tom Lane wrote:
>> I don't have a problem with switching from "$1" to "tablename_$1", or
>> some such, for auto-generated constraint names. But if it's not
>> guaranteed unique, does it really satisfy Philip's concern?

> It certainly _is_ unique within a schema ...
> (But what happens to the constraint name when the table is renamed?)

Exactly. Also consider manually-assigned constraint names that happen
to look like "foo_$n" --- these could cause trouble if table foo is
created later. To make a guarantee of uniqueness would require more
infrastructure than just a simple hack of the constraint name generator
logic.

BTW we also have some problems with auto-generated names for column
constraints; these generally look like "tablename_columnname", and
that's not unique:

regression=# create table foo (f1 int check (f1 > 0) check (f1 < 10));
ERROR: check constraint "foo_f1" already exists

regards, tom lane