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Re: query very slow when enable_seqscan=on - Mailing list pgsql-bugs

From Tom Lane
Subject Re: query very slow when enable_seqscan=on
Date
Msg-id 25494.1152036954@sss.pgh.pa.us
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In response to Re: query very slow when enable_seqscan=on  (Tomasz Ostrowski <tometzky@batory.org.pl>)
Responses Re: query very slow when enable_seqscan=on  (Tomasz Ostrowski <tometzky@batory.org.pl>)
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Tomasz Ostrowski <tometzky@batory.org.pl> writes:
> So why estimate regex expressions if there is no estimation possible?
> Let's set this estimate to be pessimistic (match everything or
> everything not null) and it will choose better plans.

Better plans for this specific example, worse plans for other cases.
Life is not that simple.

            regards, tom lane

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