Re: Nested Loop "Killer" on 8.1

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От Tom Lane
Тема Re: Nested Loop "Killer" on 8.1
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Msg-id 5388.1245963930@sss.pgh.pa.us
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Ответ на Re: Nested Loop "Killer" on 8.1  (Greg Stark <gsstark@mit.edu>)
Ответы Re: Nested Loop "Killer" on 8.1  (Greg Stark <gsstark@mit.edu>)
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Greg Stark <gsstark@mit.edu> writes:
> On Wed, Jun 24, 2009 at 1:43 PM, Dave North<DNorth@signiant.com> wrote:
> Why use "like" for a constant string with no % or _ characters? If you
> used = the planner might be able to come up with a better estimate.

Uh, it appears to me the string *does* contain _ characters; perhaps the
OP has neglected to escape those?

The planner does know enough to estimate LIKE with a fixed pattern as
being equivalent to =.  I think it knew that even back in 8.1, but am
too lazy to look right now.

            regards, tom lane

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