Re: Abnormal performance difference between Postgres and MySQL
- From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
- To: "Robert Haas" <robertmhaas(at)gmail(dot)com>, "Farhan Husain" <russoue(at)gmail(dot)com>
- Cc: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>, <pgsql-performance(at)postgresql(dot)org>
- Subject: Re: Abnormal performance difference between Postgres and MySQL
- Date: Wed, 25 Feb 2009 16:10:36 -0600
- Message-id: <49A56D7C.EE98.0025.0@wicourts.gov> <text/plain>
>>> Farhan Husain <russoue(at)gmail(dot)com> wrote:
> The machine postgres is running on has 4 GB of RAM.
In addition to the other suggestions, you should be sure that
effective_cache_size is set to a reasonable value, which would
probably be somewhere in the neighborhood of '3GB'. This doesn't
affect actual RAM allocation, but gives the optimizer a rough idea how
much data is going to be kept in cache, between both the PostgreSQL
shared_memory setting and the OS cache. It can make better choices
with more accurate information.
-Kevin
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