On Sun, Jun 11, 2017 at 10:27 AM, Peter Geoghegan <p...@bowt.ie> wrote: > Note that I introduced a new, redundant exists() in the agg_lineitem > fact table subquery. It now takes 23 seconds for me on Tomas' 10GB > TPC-H dataset, whereas the original query took over 90 minutes. > Clearly we're missing a trick or two here. I think that you need a > DAG-shaped query plan to make this work well, though, so it is > certainly a big project.
On closer examination, this seems to be due to the number of heap accesses required by an index-only scan that the original query plan uses; my test case was invalid. All the same, I understand that moving predicates into many (TPC-H) subqueries is an important optimization, and hope that more work can be done in this area. -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers