Re: NOT LIKE much faster than LIKE?

От: Andrea Arcangeli
Тема: Re: NOT LIKE much faster than LIKE?
Дата: ,
Msg-id: 20060111204639.GM15897@opteron.random
(см: обсуждение, исходный текст)
Ответ на: Re: NOT LIKE much faster than LIKE?  (Andrea Arcangeli)
Список: pgsql-performance

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NOT LIKE much faster than LIKE?  (Andrea Arcangeli, )
 Re: NOT LIKE much faster than LIKE?  (Tom Lane, )
  Re: NOT LIKE much faster than LIKE?  (Andrea Arcangeli, )
   Re: NOT LIKE much faster than LIKE?  (Christopher Kings-Lynne, )
    Re: NOT LIKE much faster than LIKE?  (Andrea Arcangeli, )
   Re: NOT LIKE much faster than LIKE?  (Tom Lane, )
    Re: NOT LIKE much faster than LIKE?  (Andrea Arcangeli, )
     Re: NOT LIKE much faster than LIKE?  (Greg Stark, )
    Re: NOT LIKE much faster than LIKE?  (Matteo Beccati, )
     Re: NOT LIKE much faster than LIKE?  (Tom Lane, )
      Re: NOT LIKE much faster than LIKE?  (Simon Riggs, )
       Re: NOT LIKE much faster than LIKE?  (Tom Lane, )
        Re: NOT LIKE much faster than LIKE?  (Simon Riggs, )
         Re: NOT LIKE much faster than LIKE?  (Tom Lane, )
          Re: NOT LIKE much faster than LIKE?  (Simon Riggs, )
           Re: NOT LIKE much faster than LIKE?  (Andrea Arcangeli, )
        Re: NOT LIKE much faster than LIKE?  (Simon Riggs, )
   Re: NOT LIKE much faster than LIKE?  (Stephan Szabo, )
 Re: NOT LIKE much faster than LIKE?  (Andrea Arcangeli, )
  Re: NOT LIKE much faster than LIKE?  (Tom Lane, )
   Re: NOT LIKE much faster than LIKE?  (Andrea Arcangeli, )
 Re: NOT LIKE much faster than LIKE?  ("Jim C. Nasby", )
  Re: NOT LIKE much faster than LIKE?  (Andrea Arcangeli, )
   Re: NOT LIKE much faster than LIKE?  (Andrea Arcangeli, )
   Re: NOT LIKE much faster than LIKE?  ("Jim C. Nasby", )
    Re: NOT LIKE much faster than LIKE?  (Tom Lane, )

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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