Matt Zagrabelny <mzagrabe@d.umn.edu> writes: > On Mon, Feb 1, 2021 at 5:57 PM Rob Sargent <robjsargent@gmail.com> wrote: >> You got one null from count(*) likely.
> What is count(*) counting then? I thought it was rows.
Yeah, but count(id) only counts rows where id isn't null.
I guess I'm still not understanding it...
I don't have any rows where id is null:
$ select count(*) from call_records where id is null; count ═══════ 0 (1 row)
Time: 0.834 ms $
select count(id) from call_records where id is null; count ═══════ 0 (1 row)
Time: 0.673 ms
Which field is count(*) counting if it is counting nulls?
You're doing a left join, so I guess there's no row where call_records.timestamp::date = 2020-08-30. That would result with a NULL id.