2009/4/15 Christian Schröder <cs@xxxxxxxxx>: > Grzegorz Jaśkiewicz wrote: >> >> set work_mem=24000; before running the query. >> >> postgres is doing merge and sort on disc, that's always slow. >> > > Ok, but why is the plan different in 8.2? As you can see the same query is > really fast in 8.2, but slow in 8.3. Did that set help ? I think Tom will know more about it, but probably (and I am guessing here, to be honest) - Materialize plan wasn't either available, or didn't appear too be a planners favourite. on 8.2 the two loops instead were were much faster. Can you try increasing stat target to 100, vacuum analyze and see if different plan is choosen ? Again, I don't know at that point why is it so - just trying to suggests things that I would try . >> is there an index on column isin ? >> > > There is a separate index on the isin column of the attachment_isins table > (attachment_isins_isin_idx). The other table (rec_isins) has the combination > of attachment and isin as primary key which creates an implicit index. Can > this index be used for the single column isin? And again: Why doesn't this > matter in 8.2?? well, it is a different major release, and differences between 8.2->8.3 are vast. -- GJ -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
