From: Tom Lane <tgl@sss.pgh.pa.us>
To: sushant354@gmail.com
Cc: Tomas Vondra <tv@fuzzy.cz>
Cc: pgsql-performance@postgresql.org
Subject: Re: sequential scan unduly favored over text search gin index
Date: Tue, 21 Jun 2011 01:53:19 -0400
Message-ID: <4289.1308635599@sss.pgh.pa.us> (raw)
In-Reply-To: <1308623134.1747.1.camel@dragflick>
References: <1308584339.2488.12.camel@dragflick>
<4DFF27C5020000250003E9A4@gw.wicourts.gov>
<1308585840.2488.13.camel@dragflick>
<4DFF990F.8080906@fuzzy.cz>
<1308623134.1747.1.camel@dragflick>
Sushant Sinha <sushant354@gmail.com> writes:
>> I guess you could poke the planner towards the bitmap scan by lowering
>> the random_page_cost (the default value is 4, I'd say lowering it to 2
>> should do the trick).
> The numbers that I gave was after setting random_page_cost = 1.0 After
> this I don't know what to do.
I think part of the issue here is that the @@ operator is expensive,
and so evaluating it once per row is expensive, but the pg_proc.procost
setting for it doesn't adequately reflect that. You could experiment
with tweaking that setting ...
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, sushant354@gmail.com, tv@fuzzy.cz
Subject: Re: sequential scan unduly favored over text search gin index
In-Reply-To: <4289.1308635599@sss.pgh.pa.us>
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