Craig, I'm not using a TEMP TABLE in this DELETE however I have tried an ANALYZE prior to the DELETE but it hardly makes a dent in the time. Please look at the other follow-up email I just sent for full details. Greg -----Original Message----- From: Craig A. James [mailto:cjames@xxxxxxxxxxxxxxxx] Sent: Monday, April 09, 2007 5:58 PM To: Spiegelberg, Greg Cc: pgsql-performance@xxxxxxxxxxxxxx Subject: Re: [PERFORM] DELETE with filter on ctid Spiegelberg, Greg wrote: > We have a query which generates a small set of rows (~1,000) which are > to be used in a DELETE on the same table. The problem we have is that > we need to join on 5 different columns and it takes far too long. You may have encountered the same problem I did: You *must* run ANALYZE on a temporary table before you use in another query. It's surprising that this is true even for very small tables (a few hundred to a few thousand rows), but it is. I had a case where I created a "scratch" table like yours, and the before/after ANALYZE performance was the difference between 30 seconds and a few milliseconds for the same query. Craig
