Re: count(*) vs count(id)

On Wed, 2021-02-03 at 10:54 +0100, Karsten Hilbert wrote:
> > I just ran a few practical tests on large (~14mil rows) tables that have
> > multiple indexes.
> > SELECT COUNT(id) forces PostgreSQL to use the primary key index.
> > SELECT COUNT(*) allows PostgreSQL to chose an index to use and it seems to
> > be choosing one of smaller size which leads to less IO and hence returns
> > the result faster.
>
> Would you mind throwing in a test for
>
> select count(1) ...

No need to test. That will be slightly slower because it repeatedly checks
if 1 is NULL or not.

Yours,
Laurenz Albe
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