Re: random_page_costs - are defaults of 4.0 realistic for SCSI RAID 1

From: Mark Mielke <mark(at)mark(dot)mielke(dot)cc>
To: Luke Lonergan <llonergan(at)greenplum(dot)com>
Cc: Carlo Stonebanks <stonec(dot)register(at)sympatico(dot)ca>, pgsql-performance(at)postgresql(dot)org
Subject: Re: random_page_costs - are defaults of 4.0 realistic for SCSI RAID 1
Date: 2007-09-10 20:52:56
Message-ID: 46E5AEA8.4010809@mark.mielke.cc
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Luke Lonergan wrote:
> Should be a lot higher, something like 10-15 is approximating accurate.
>
In my own case, I have a much smaller database that I normally work
with, where everything should fit in memory (100 Mbytes?), and reducing
it to 3.0 has resulted in consistently better timings for me. I think
this means that the planner doesn't understand my database size :
effective memory size ratio. :-)

Anyways - my point is that if you change the default to 10 you may hurt
people like me.

Cheers,
mark

--
Mark Mielke <mark(at)mielke(dot)cc>

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