Re: pb with join plan

On Tue, Jun 20, 2023 at 10:14 PM David Rowley <dgrowleyml(at)gmail(dot)com> wrote:

> On Wed, 21 Jun 2023 at 07:42, Marc Millas <marc(dot)millas(at)mokadb(dot)com> wrote:
> > But if I do the same with clause one OR clause 2, I have to kill the
> request after an hour, seeing the filesystem showing more than 140 Mb of
> increased usage.
>
> > So, before providing the 3 explain plans (I must anonymize everything,
> so somewhat boring) I would like to know if there is some obvious thing I
> am missing.
> > all tables have been vacuum analyzed.
>
> I believe you can anonymise the explain with https://explain.depesz.com/
>
> link to the anonymized plan of the req with one clause :
https://explain.depesz.com/s/TWp4

It's pretty hard to say until we see the query, but having an OR in
> the join condition makes it impossible to Hash or Merge join, so
> perhaps it's slow due to Nested Loop join.
>
> You could consider rewriting the query to use a UNION or a UNION ALL
> separating out each branch of the OR into a UNION of its own. That
> would allow Hash and Merge join to work again. However, that's all
> speculation until you provide more details.
>
> https://wiki.postgresql.org/wiki/Guide_to_reporting_problems
>
> David
>

Marc MILLAS