On Wed, 21 Jun 2023 at 07:42, Marc Millas <marc.millas@mokadb.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.
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.