Re: NOT LIKE much faster than LIKE? - Mailing list pgsql-performance

From Tom Lane
Subject Re: NOT LIKE much faster than LIKE?
Date
Msg-id 7924.1136950830@sss.pgh.pa.us
Whole thread Raw
In response to Re: NOT LIKE much faster than LIKE?  (Simon Riggs <simon@2ndquadrant.com>)
Responses Re: NOT LIKE much faster than LIKE?  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-performance
Simon Riggs <simon@2ndquadrant.com> writes:
> I meant use the same sampling approach as I was proposing for ANALYZE,
> but do this at plan time for the query. That way we can apply the
> function directly to the sampled rows and estimate selectivity.

I think this is so unlikely to be a win as to not even be worth spending
any time discussing.  The extra planning time across all queries will
vastly outweigh the occasional improvement in plan choice for some
queries.

            regards, tom lane

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