Jeff Janes <jeff.janes@xxxxxxxxx> writes: > On Wed, May 24, 2017 at 1:42 PM, Sam Saffron <sam.saffron@xxxxxxxxx> wrote: >> I have this query that is not picking the right index unless I hard code >> dates: >> ... > Maybe it should first execute the subquery and then re-plan the rest of the > query based on the results. But there is no provision for it to do that, > and no concrete plans (that I know of) to implement such a thing. I don't know of any plans for that, either. >> The results here simply do not make sense to me, should I be piping >> dates in here to avoid this issue and running 2 queries instead of 1? > That is the most pragmatic approach. It isn't very nice, but the > alternatives are worse. You could probably get the behavior you want by replacing the subquery with a "stable" function: create function first_topic_unread_for(userid int) returns timestamp as 'select first_topic_unread_at from user_stats us where us.user_id = $1' language sql stable; SELECT "topics".* FROM "topics" WHERE topics.last_unread_at >= first_topic_unread_for(1); This should convince the planner to pre-run the function to get an estimated result at plan time. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
