Re: Pathify RHS unique-ification for semijoin planning - Mailing list pgsql-hackers

On Wed, Jul 23, 2025 at 5:11 PM Álvaro Herrera <alvherre@kurilemu.de> wrote:
> As a very trivial test on this patch, I ran the query in your opening
> email, both with and without the patch, scaling up the size of the table
> a little bit.

> This is a really nice improvement.  I think we could find queries that
> are arbitrarily faster, by feeding enough tuples to the unnecessary Sort
> nodes.

Thank you for testing this patch!

In addition to eliminating unnecessary sort nodes, this patch also
allows us to exploit pre-sorted paths that aren't necessarily the
cheapest total during the unique-ification step.  It also allows the
use of parallel plans for that step on large tables.  I think we could
also find queries that become faster as a result of these improvements.

Thanks
Richard