Re: should check collations when creating partitioned index

Jeff Davis <pgsql@j-davis.com> writes:
> In the patch, you check for an exact collation match. Considering this
> case only depends on equality, I think it would be correct if the
> requirement was that (a) both collations are deterministic; or (b) the
> collations match exactly.

You keep harping on this idea that we are only concerned with equality,
but I think you are wrong.  We expect a btree index to provide ordering
not only equality, and this example definitely is a btree index.

Possibly, with a great deal more specificity added to the check, we
could distinguish the cases where ordering can't matter and allow
collation variance then.  I do not see the value of that, especially
not when measured against the risk of introducing subtle bugs.

            regards, tom lane