| From: | Andrea Arcangeli <andrea(at)cpushare(dot)com> |
|---|---|
| To: | |
| Cc: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: NOT LIKE much faster than LIKE? |
| Date: | 2006-01-11 20:46:39 |
| Message-ID: | 20060111204639.GM15897@opteron.random |
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| Thread: | |
| Lists: | pgsql-performance |
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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