Re: Surprising benchmark count(1) vs. count(*)

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От
Tom Lane
Тема
Re: Surprising benchmark count(1) vs. count(*)
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22758.1568902312@sss.pgh.pa.us
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Re: Surprising benchmark count(1) vs. count(*) (Thomas Kellerer)
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Surprising benchmark count(1) vs. count(*) Thomas Kellerer <spam_eater@gmx.net>
Re: Surprising benchmark count(1) vs. count(*) Laurenz Albe <laurenz.albe@cybertec.at>
Re: Surprising benchmark count(1) vs. count(*) Thomas Kellerer <spam_eater@gmx.net>
Re: Surprising benchmark count(1) vs. count(*) Tom Lane <tgl@sss.pgh.pa.us>
Re: Surprising benchmark count(1) vs. count(*) Adam Brusselback <adambrusselback@gmail.com>
Re: Surprising benchmark count(1) vs. count(*) Tom Lane <tgl@sss.pgh.pa.us> 
Thomas Kellerer  writes:
> Laurenz Albe schrieb am 19.09.2019 um 12:22:
>> "count(1)" has to check if 1 IS NULL for each row, because NULL
>> values are not counted.  "count(*)" doesn't have to do that.

> But 1 is a constant, why does it need to check it for each row? 

[ shrug... ]  There's no special optimization for that case.
And I can't say that it seems attractive to add one.

			regards, tom lane
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