From: | Klint Gore <kg(at)kgb(dot)une(dot)edu(dot)au> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Jim C(dot)Nasby <jnasby(at)pervasive(dot)com>, pgsql-performance(at)postgresql(dot)org, Jeffrey Tenny <jeffrey(dot)tenny(at)comcast(dot)net> |
Subject: | Re: performance question (something to do w/ parameterized |
Date: | 2006-05-09 00:10:19 |
Message-ID: | 445FDDEB225.3451KG@129.180.47.120 |
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Lists: | pgsql-hackers pgsql-performance |
On Mon, 08 May 2006 19:37:37 -0400, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Jeffrey Tenny <jeffrey(dot)tenny(at)comcast(dot)net> writes:
> > The server was already running with random_page_cost=2 today for all tests, because of
> > the mods I've made to improve other problem queries in the past (my settings noted below, and
> > before in another msg on this topic).
>
> > So to nail this particular query something additional is required (even lower random_page_cost?).
> > What's a good value for slower processors/memory and database in memory?
>
> If you're pretty sure the database will always be RAM-resident, then 1.0
> is the theoretically correct value.
Would it be possible to craft a set of queries on specific data that
could advise a reasonable value for random_page_cost?
What sort of data distribution and query type would be heavily dependant
on random_page_cost? i.e. randomness of the data, size of the data
compared to physical memory.
klint.
+---------------------------------------+-----------------+
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