On Fri, Jul 13, 2012 at 1:28 PM, Eoghan Murray <eoghan@qatano.com> wrote:
> Thank you Claudio,
>
> I haven't touched the 9.1 configuration (with the exception of toggling the
> enable_material setting). http://pastebin.com/nDjcYrUd
> As far as I can remember I haven't changed the 8.4 configuration:
> http://pastebin.com/w4XhDRX4
Maybe that's your problem. Postgres default configuration is not only
suboptimal, but also a poor reflection of your hardware (what's your
hardware, btw?). Which means postgres' expected costs won't hold. I'm
thinking especially about your effective_cache_size, which may
influence postgres' decision to use one join method vs another, but
many other settings would probable influence.
Spend a bit of time to configure both servers such that the
configuration reflects the hardware, and try your queries again.