Re: count(*) vs count(id)
| От | Matt Zagrabelny |
|---|---|
| Тема | Re: count(*) vs count(id) |
| Дата | |
| Msg-id | CAOLfK3XBUxP3jbAnKVn9cei4hh4snozhVj5yjxCipVnYvwfTsA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: count(*) vs count(id) (Tom Lane <tgl@sss.pgh.pa.us>) |
| Ответы |
Re: count(*) vs count(id)
Re: count(*) vs count(id) Re: count(*) vs count(id) Re: count(*) vs count(id) |
| Список | pgsql-general |
On Mon, Feb 1, 2021 at 6:35 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
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
$
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
count
═══════
0
(1 row)
Time: 0.673 ms
Which field is count(*) counting if it is counting nulls?
-m
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