Awesome, that did the trick. Thanks Tom! So I understand better, why is my case not the normal, better case? (I assume the long-term fix is post-9.0, right?) On Feb 15, 2010, at 9:26 AM, Tom Lane wrote: > Ben Chobot <bench@xxxxxxxxxxxxxxx> writes: >> On Feb 15, 2010, at 7:59 AM, Kevin Grittner wrote: >>> Could you show the query, along with table definitions (including >>> indexes)? > >> Oh, yeah, I suppose that would help. :) > >> http://wood.silentmedia.com/bench/query_and_definitions > > It looks like the problem is that the EXISTS sub-query is getting > converted into a join; which is usually a good thing but in this case it > interferes with letting the users table not be scanned completely. > The long-term fix for that is to support nestloop inner indexscans where > the index key comes from more than one join level up, but making that > happen isn't too easy. > > In the meantime, I think you could defeat the "optimization" by > inserting LIMIT 1 in the EXISTS sub-query. > > regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
