From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jim C. Nasby <jnasby@pervasive.com>
Cc: Andrea Arcangeli <andrea@cpushare.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: NOT LIKE much faster than LIKE?
Date: Wed, 11 Jan 2006 16:13:20 -0500
Message-ID: <28232.1137014000@sss.pgh.pa.us> (raw)
In-Reply-To: <20060111210221.GD63175@pervasive.com>
References: <20060110014447.GB18474@opteron.random>
<20060111184032.GS3902@pervasive.com>
<20060111203947.GL15897@opteron.random>
<20060111210221.GD63175@pervasive.com>
"Jim C. Nasby" <jnasby@pervasive.com> writes:
> On Wed, Jan 11, 2006 at 09:39:47PM +0100, Andrea Arcangeli wrote:
>> The index only helps the above query with = 0 and not the one with != 0,
>> but it seems not needed in practice.
> I suspect this is because of a lack of stats for functional indexes.
No, it's because != isn't an indexable operator.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, jnasby@pervasive.com, andrea@cpushare.com
Subject: Re: NOT LIKE much faster than LIKE?
In-Reply-To: <28232.1137014000@sss.pgh.pa.us>
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