Re: Understanding tsearch2 performance

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: <ivoras(at)freebsd(dot)org>,<pgsql-performance(at)postgresql(dot)org>
Subject: Re: Understanding tsearch2 performance
Date: 2010-07-14 14:03:26
Message-ID: 4C3D7D5E0200002500033548@gw.wicourts.gov
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Ivan Voras < ivoras(at)freebsd(dot)org > wrote:
> On 07/14/10 15:49, Stephen Frost wrote:

>> Regarding the statistics, it's entirely possible that the index
>> is *not* the fastest way to pull this data (it's nearly 10% of
>> the table..)
>
> I think that what I'm asking here is: is it reasonable for
> tsearch2 to extract 8,500 rows from an index of 90,000 rows in 118
> ms, given that the approximately same task can be done with an
> unindexed "LIKE" operator in nearly the same time?

The answer is "yes." When it's 10% of the table, a sequential scan
can be more efficient than an index, as Stephen indicated.

-Kevin

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