| From: | Shaun Thomas <sthomas(at)optionshouse(dot)com> |
|---|---|
| To: | Dave Johansen <davejohansen(at)gmail(dot)com> |
| Cc: | pgsql-performance <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Unexpected pgbench result |
| Date: | 2013-12-20 14:10:32 |
| Message-ID: | 52B44FD8.2030105@optionshouse.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On 12/19/2013 04:06 PM, Dave Johansen wrote:
> Right now, we're running a RAID 1 for pg_clog, pg_log and pg_xlog and
> then a RAID 1+0 with 12 disks for the data. Would there be any benefit
> to running a separate RAID 1+0 with a tablespace for the indexes?
Not really. PostgreSQL doesn't currently support parallel backend
fetches, aggregation, or really anything. It's looking like 9.4 will get
us a lot closer to that, but right now, everything is serial.
Serial or not, separate backends will have separate read concerns, and
PostgreSQL 9.2 and above *do* support index only scans. So
theoretically, you might actually see some benefit there. If it were me
and I had spindles available, I would just increase the overall size of
the pool. It's a lot easier than managing multiple tablespaces.
--
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 500 | Chicago IL, 60604
312-676-8870
sthomas(at)optionshouse(dot)com
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