Re: Slow HashAggregate/cache access

Alexandre de Arruda Paes <adaldeia(at)gmail(dot)com> wrote:

> We did the following tests:
>
> 1) Postgresql 9.3 and Oracle 10 in a desktop machine(8 GB RAM, 1 SATA disk,Core i5)
> 2) Postgresql 9.3 in a server + FC storage (128 GB RAM, Xeon 32 cores, SAS disks)

That's only part of the information we would need to be able to
give specific advice. Please read this page:

https://wiki.postgresql.org/wiki/SlowQueryQuestions

One possibility is that you are running with the default
configuration, rather than having tuned for the hardware. You are
very likely to need to adjust shared_buffers, effective_cache_size,
work_mem, maintenance_work_mem, random_page_cost, cpu_tuple_cost,
and (at least for the second machine) effective_io_concurrency. If
the queries have a lot of joins you may need to increase
from_collapse_limit and/or join_collapse_limit. You also may need
to adjust [auto]vacuum and/or background writer settings. Various
OS settings may matter, too.

To get a handle on all this, it might be worth looking for Greg
Smith's book on PostgreSQL high performance.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company