| From: | Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> |
|---|---|
| To: | Marc Mamin <M(dot)Mamin(at)intershop(dot)de>, 'Geoff Winkless' <pgsqladmin(at)geoff(dot)dj>, Postgres General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: select count(*); |
| Date: | 2015-06-11 14:30:33 |
| Message-ID: | 55799B89.2010902@aklaver.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
On 06/11/2015 07:17 AM, Marc Mamin wrote:
>>> That's the point. * has no meaning without FROM
>
>
>> But COUNT(*)
>>
>> does have meaning - it means "the number of rows".
>
> which rows? :-)
To follow up on the post from Chris Mair:
test=> select count(*), 'foo';
count | ?column?
-------+----------
1 | foo
See also:
http://www.postgresql.org/docs/9.4/interactive/functions-aggregate.html
count(*) bigint number of input rows
>
>> It's not counting the number of columns in the row, so postgres doesn't need to know what columns exist in the row to return a row count.
>
>> Geoff
>
>
--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com
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