Greg Spiegelberg wrote:
I've been following this thread closely as I have the same problem with an UPDATE. Everything is identical here right down to the strace output.
Has anyone found a workaround or resolved the problem? If not, I have test systems here which I can use to help up test and explore.
I'm still gathering data. The explain analyze I'd expected to finish Thursday afternoon hasn't yet. I'm going to kill it and try a few smaller runs, increasing in size, until the behavior manifests.
I've replaced my atrocious UPDATE with the following.
begin; -- Drop all contraints alter table ORIG drop constraint ...; -- Drop all indexes drop index ...; -- Update update ORIG set column=... where...; commit;
Problem is when I recreate the indexes and add the constraints back on ORIG I end up with the same long running process. The original UPDATE runs for about 30 minutes on a table of 400,000 with the WHERE matching about 70% of the rows. The above runs for about 2 minutes without adding the constraints or indexes however adding the constraints and creating the dropped indexes negates any gain.
RedHat 7.3 + Kernel 2.4.24 + ext3 + PostgreSQL 7.3.5 Dual PIII 1.3'ishGHz, 2GB Memory U160 OS drives and a 1Gbps test SAN on a Hitachi 9910
-- Greg Spiegelberg Sr. Product Development Engineer Cranel, Incorporated. Phone: 614.318.4314 Fax: 614.431.8388 Email: [EMAIL PROTECTED] Cranel. Technology. Integrity. Focus.
---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match