Re: sequential scan unduly favored over text search gin index

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: sushant354(at)gmail(dot)com
Cc: Tomas Vondra <tv(at)fuzzy(dot)cz>, pgsql-performance(at)postgresql(dot)org
Subject: Re: sequential scan unduly favored over text search gin index
Date: 2011-06-21 05:53:19
Message-ID: 4289.1308635599@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

Sushant Sinha <sushant354(at)gmail(dot)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

In response to

Responses

Browse pgsql-performance by date

  From Date Subject
Next Message Greg Smith 2011-06-21 06:33:40 Re: Contemplating SSD Hardware RAID
Previous Message Dan Harris 2011-06-21 03:54:26 Contemplating SSD Hardware RAID