Re: Why is a sort required for this query? (IS NULL predicate on leading key column) - Mailing list pgsql-performance

Jerry Brenner <jbrenner@guidewire.com> writes:
> I'm wondering why a sort is required for this query, as the index should be
> providing the required ordering to satisfy the ORDER BY clause.  Does it
> have to do with the IS NULL predicate on the leading key column in the
> index?

IS NULL is not seen as an equality condition, no.  It's pretty much
of a hack that makes it an indexable condition at all, and we don't
really do any advanced optimization with it.

            regards, tom lane