From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Thomas Kellerer <spam_eater@gmx.net>
To: pgsql-performance@lists.postgresql.org
Subject: Re: Surprising benchmark count(1) vs. count(*)
Date: Thu, 19 Sep 2019 12:22:42 +0200
Message-ID: <ab88db80f032933ff603d9d59745e8a09196bc1e.camel@cybertec.at> (raw)
In-Reply-To: <df354b76-a645-73fc-9645-4508e5291d71@gmx.net>
References: <df354b76-a645-73fc-9645-4508e5291d71@gmx.net>
On Thu, 2019-09-19 at 12:09 +0200, Thomas Kellerer wrote:
> https://blog.jooq.org/2019/09/19/whats-faster-count-or-count1/
>
> Is there a reason why count(*) seems to be faster?
"count(*)" is just the SQL standard's way of saying what you'd
normally call "count()", that is, an aggregate without arguments.
"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.
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
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Subject: Re: Surprising benchmark count(1) vs. count(*)
In-Reply-To: <ab88db80f032933ff603d9d59745e8a09196bc1e.camel@cybertec.at>
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