Re: Hash Join vs Nested Loops in 7.2.1 ...

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От Tom Lane
Тема Re: Hash Join vs Nested Loops in 7.2.1 ...
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Msg-id 10456.1018381931@sss.pgh.pa.us
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Ответ на Re: Hash Join vs Nested Loops in 7.2.1 ...  (Ed Loehr <pggeneral@bluepolka.net>)
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Ed Loehr <pggeneral@bluepolka.net> writes:
> What I neglected to mention was that the planner was *choosing* the
> slower hashjoin plan over the much faster nested loop plan without any
> PGOPTIONS set or any postgresql.conf changes to enable_*, thus the
> motivation for a "thumb on the scales."  After upping the number of
> shared buffers, it has begun choosing the smart plan 1-second plan,

Interesting.  The estimated cost of indexscans is dependent on
shared_buffers, but not so dependent that I'd have expected it to make a
difference here.  What were the EXPLAIN numbers you were getting, again?

            regards, tom lane

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