Thanks Michael. I'll give some join alternatives a shot first... but, that's cool.
What about OFFSET 0 makes this approach work? I'm thinking the OFFSET 0 create an optimization barrier that prevents the planner from collapsing that sub-query into the top query, and enforces ordering in the query? I appreciate your thoughts, thank-you very much for the feedback. Mathieu On Wed, Aug 21, 2019 at 12:08 PM Michael Lewis <mle...@entrata.com> wrote: > If those conditions that are throwing off the stats are expected to be > minimally impactful/filtering few rows, then you can use the one > tried-and-true optimizer hint (aside from materialized CTEs, stylized > indexes, etc) --- OFFSET 0 at the end of a sub-query. > > SELECT * FROM ( [your existing query without the sub-selects that are > complicated and produce bad estimates] OFFSET 0 ) WHERE [your other > conditions that don't produce good estimates] > > If there is correlation between field1 and field2, you might also look at > CREATE STATISTICS assuming you are on PG 10 or 11. > > Before I do any of that, I would try LEFT JOIN for Table3 and Table4 then > use the where conditon "AND 2 = COALESCE( Table3.Status, Table4.Status" > and see if the optimizer likes that option better. >
