From: | Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com> |
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To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
Cc: | pgsql-performance(at)postgresql(dot)org, gnuoytr(at)rcn(dot)com, Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com> |
Subject: | Re: How does PG know if data is in memory? |
Date: | 2010-10-13 03:16:25 |
Message-ID: | 4CB52489.8050309@cheapcomplexdevices.com |
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Lists: | pgsql-performance |
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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