Re: Calculating selectivity for the query-planner on ts_vector colums.

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jesper Krogh <jesper(at)krogh(dot)cc>
Cc: "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Calculating selectivity for the query-planner on ts_vector colums.
Date: 2009-10-23 19:11:15
Message-ID: 25354.1256325075@sss.pgh.pa.us
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Jesper Krogh <jesper(at)krogh(dot)cc> writes:
> It seems to me that the row estimates on a ts_vector search is a bit on
> the low side for terms that is not in th MCV-list in pg_stats:

tsvector has its own selectivity estimator that's not like plain scalar
equality. Look into src/backend/tsearch/ts_selfuncs.c if you want to
see the rules.

regards, tom lane

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