Re: procost for to_tsvector

On Wed, Mar 11, 2015 at 02:40:16PM +0000, Andrew Gierth wrote:
> An issue that comes up regularly on IRC is that text search queries,
> especially on relatively modest size tables or for relatively
> non-selective words, often misplan as a seqscan based on the fact that
> to_tsvector has procost=1.
>
> Clearly this cost number is ludicrous.
>
> Getting the right cost estimate would obviously mean taking the cost of
> detoasting into account, but even without doing that, there's a strong
> argument that it should be increased to at least the order of 100.
> (With the default cpu_operator_cost that would make each to_tsvector
> call cost 0.25.)
>
> (The guy I was just helping on IRC was seeing a slowdown of 100x from a
> seqscan in a query that selected about 50 rows from about 500.)

Where are we on setting increasing procost for to_tsvector?

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Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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