Re: inefficient query plan with left joined view

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От Tom Lane
Тема Re: inefficient query plan with left joined view
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Msg-id 4509.1043793660@sss.pgh.pa.us
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Ответ на Re: inefficient query plan with left joined view  (Andreas Pflug <Andreas.Pflug@web.de>)
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Andreas Pflug <Andreas.Pflug@web.de> writes:
> As the example shows even
> columns that are never used will be taken into account when checking
> has_nullable_targetlist.

It's not really practical to do otherwise, as the code that needs to
check this doesn't have access to a list of the columns actually used.
Even if we kluged things up enough to make it possible to find that out,
that would merely mean that *some* of your queries wouldn't have a
problem.

What about improving the intelligence of the nullability check --- or do
you have non-strict expressions in there?

            regards, tom lane

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