From: Andrea Arcangeli <andrea@cpushare.com>
Cc: Jim C. Nasby <jnasby@pervasive.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: NOT LIKE much faster than LIKE?
Date: Wed, 11 Jan 2006 21:46:39 +0100
Message-ID: <20060111204639.GM15897@opteron.random> (raw)
In-Reply-To: <20060111203947.GL15897@opteron.random>
References: <20060110014447.GB18474@opteron.random>
<20060111184032.GS3902@pervasive.com>
<20060111203947.GL15897@opteron.random>
On Wed, Jan 11, 2006 at 09:39:47PM +0100, Andrea Arcangeli wrote:
> On Wed, Jan 11, 2006 at 12:40:32PM -0600, Jim C. Nasby wrote:
> > On Tue, Jan 10, 2006 at 02:44:47AM +0100, Andrea Arcangeli wrote:
> > > "cooperative" runs "WHERE kernel_version NOT LIKE '%% PREEMPT %%'", while
> > > "preempt" runs "WHERE kernel_version LIKE '%% PREEMPT %%'. The only difference
> >
> > One thing you could do is change the like to:
> >
> > WHERE position(' PREEMPT ' in kernel_version) != 0
>
> That alone fixed it, with this I don't even need the index (yet). Thanks
> a lot.
The fix is online already w/o index:
http://klive.cpushare.com/?branch=all&scheduler=preemptive
Of course I'm still fully available to test any fix for the previous
LIKE query if there's interest.
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To: pgsql-performance@postgresql.org
Cc: andrea@cpushare.com, jnasby@pervasive.com
Subject: Re: NOT LIKE much faster than LIKE?
In-Reply-To: <20060111204639.GM15897@opteron.random>
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