From: Ron Mayer <rm_pg@cheapcomplexdevices.com>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: pgsql-performance@postgresql.org, gnuoytr@rcn.com, Ron Mayer <rm_pg@cheapcomplexdevices.com>
Subject: Re: How does PG know if data is in memory?
Date: Tue, 12 Oct 2010 20:16:25 -0700
Message-ID: <4CB52489.8050309@cheapcomplexdevices.com> (raw)
In-Reply-To: <4CB42BFC0200002500036805@gw.wicourts.gov>
References: <AANLkTin5G0jXUbeNdC+1s9LQpk1ZpvDuX-6n90oonen3@mail.gmail.com>
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<20101011231134.ANB76937@ms14.lnh.mail.rcn.net>
<4CB42BFC0200002500036805@gw.wicourts.gov>
Kevin Grittner wrote:
>
> ...Sybase named caches...segment off portions of the memory for
> specific caches... bind specific database
> objects (tables and indexes) to specific caches. ...
>
> When I posted to the list about it, the response was that LRU
> eviction was superior to any tuning any human would do. I didn't
> and don't believe that....
>
> FWIW, the four main reasons for using it were:
> (1) Heavily used data could be kept fully cached in RAM...
Lightly-used-but-important data seems like another use case.
LRU's probably far better than me at optimizing for the total
throughput and/or average response time. But if there's a
requirement:
"Even though this query's very rare, it should respond
ASAP, even at the expense of the throughput of the rest
of the system."
it sounds like this kind of hand-tuning might be useful.
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To: pgsql-performance@postgresql.org
Cc: rm_pg@cheapcomplexdevices.com, Kevin.Grittner@wicourts.gov
Subject: Re: How does PG know if data is in memory?
In-Reply-To: <4CB52489.8050309@cheapcomplexdevices.com>
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