From: Greg Stark <gsstark@mit.edu>
To: Andrea Arcangeli <andrea@cpushare.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: NOT LIKE much faster than LIKE?
Date: 10 Jan 2006 10:11:18 -0500
Message-ID: <87y81oyv6x.fsf@stark.xeocode.com> (raw)
In-Reply-To: <20060110034721.GC20168@opteron.random>
References: <20060110014447.GB18474@opteron.random>
<24021.1136858688@sss.pgh.pa.us>
<20060110022303.GA20168@opteron.random>
<24372.1136861684@sss.pgh.pa.us>
<20060110034721.GC20168@opteron.random>
Andrea Arcangeli <andrea@cpushare.com> writes:
> Fixing this with proper stats would be great indeed. What would be the
> most common value for the kernel_version? You can see samples of the
> kernel_version here http://klive.cpushare.com/2.6.15/ . That's the
> string that is being searched against both PREEMPT and SMP.
Try something like this where attname is the column name and tablename is,
well, the tablename:
db=> select most_common_vals from pg_stats where tablename = 'region' and attname = 'province';
most_common_vals
------------------
{ON,NB,QC,BC}
Note that there's a second column most_common_freqs and to do this would
really require doing a weighted average based on the frequencies.
--
greg
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To: pgsql-performance@postgresql.org
Cc: gsstark@mit.edu, andrea@cpushare.com, tgl@sss.pgh.pa.us
Subject: Re: NOT LIKE much faster than LIKE?
In-Reply-To: <87y81oyv6x.fsf@stark.xeocode.com>
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