From: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
---|---|
To: | sthomas(at)optionshouse(dot)com |
Cc: | Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-performance(at)postgresql(dot)org, Greg Smith <greg(at)2ndQuadrant(dot)com> |
Subject: | Re: PostgreSQL settings for running on an SSD drive |
Date: | 2013-06-20 21:32:34 |
Message-ID: | 51C374F2.4050208@dunslane.net |
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Lists: | pgsql-performance |
On 06/20/2013 05:23 PM, Shaun Thomas wrote:
> On 06/20/2013 03:32 PM, Josh Berkus wrote:
>
>> Did you compare setting RPC to 1.0 vs. setting it to 1.1, or something
>> else just slightly higher than SPC?
>
> Yes, actually. My favored setting when we were on 8.3 was 1.5. But
> something with the planner changed pretty drastically when we went to
> 9.1, and we were getting some really bad query plans unless we
> *strongly* suggested RPC was cheap. I was afraid I'd have to go lower,
> but 1 seemed to do the trick.
>
That would be perverse, surely, but on Fusion-IO RPC = SPC seems to make
sense unless you assume that cache misses will be higher for random
reads than for sequential reads.
cheers
andrew
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