From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomasz Ostrowski <tometzky@batory.org.pl>
Cc: pgsql-bugs@postgresql.org
Subject: Re: query very slow when enable_seqscan=on
Date: Tue, 04 Jul 2006 14:15:54 -0400
Message-ID: <25494.1152036954@sss.pgh.pa.us> (raw)
In-Reply-To: <20060704144406.GA21511@batory.org.pl>
References: <20060703203105.GA2801@batory.org.pl>
<7353.1151967946@sss.pgh.pa.us>
<20060704083733.GA20102@batory.org.pl>
<13853.1152021389@sss.pgh.pa.us>
<20060704144406.GA21511@batory.org.pl>
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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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, tometzky@batory.org.pl, pgsql-bugs@postgresql.org
Subject: Re: query very slow when enable_seqscan=on
In-Reply-To: <25494.1152036954@sss.pgh.pa.us>
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