| From: | Greg Smith <greg(at)2ndquadrant(dot)com> |
|---|---|
| To: | Hannu Krosing <hannu(at)krosing(dot)net> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Peter Hussey <peter(at)labkey(dot)com>, pgsql-performance <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Questions on query planner, join types, and work_mem |
| Date: | 2010-08-04 20:40:14 |
| Message-ID: | 4C59D02E.7040908@2ndquadrant.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
Hannu Krosing wrote:
> Do you mean "written to disk", or written out from shared_buffers to
> disk cache ?
>
The later turns into the former eventually, so both really. The kernel
will do some amount of write combining for you if you're lucky. But not
in all cases; it may decide to write something out to physical disk
before the second write shows up.
--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.us
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