Jeff,
> Box #1 is our "production" server, and actually has more going on during
> the day than #2 which is the "test" server. #1 has "shared_buffers" set
> to 131072; #2 has it at 250000. Hardware, O/S and PostgreSQL versions are
> all identical. Software executing the query (Perl code using DBI) is the
> same.
First, I think you need to join the PGSQL-PERFORMANCE list; we discuss things
like your issue all the time there.
Collective wisdom on that list is that shared_buffer settings above 5000-6000
actually degrade performance by robbing the kernel buffer of resources. The
postgres shared_buffers are just a "holding area" for operations spooling to
the kernel buffer which actually does most of the work.
HTH.
--
-Josh BerkusAglio Database SolutionsSan Francisco
