Why could GEQO produce plans with lower costs than the standard_join_search?

From: Donald Dong <xdong(at)csumb(dot)edu>
To: PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Why could GEQO produce plans with lower costs than the standard_join_search?
Date: 2019-05-07 23:29:04
Message-ID: 5A76B3F6-200F-4721-94E9-9C377F582568@csumb.edu
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Hi,

I was expecting the plans generated by standard_join_search to have lower costs
than the plans from GEQO. But after the results I have from a join order
benchmark show that GEQO produces plans with lower costs most of the time!

I wonder what is causing this observation? From my understanding,
standard_join_search is doing a complete search. So I'm not sure how the GEQO
managed to do better than that.

Thank you,
Donald Dong

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Michael Paquier 2019-05-07 23:43:11 Re: Heap lock levels for REINDEX INDEX CONCURRENTLY not quite right?
Previous Message Stephen Frost 2019-05-07 22:58:24 Re: New EXPLAIN option: ALL