Oleg Bartunov wrote:
>
> I got a problem with query:
>
> select distinct (date), bytes from access_log;
>
> which works but not as I expect. I thought this query will select
> all rows with distinct values of 'date' column, but it get
> distinct pairs 'date, bytes' . From documnetation I see
>
> "DISTINCT will eliminate all duplicate rows from the selection.
> DISTINCT ON column will eliminate all duplicates in the specified column;
> this is equivalent to using GROUP BY column.
If it is equivalent to GROUP BY then it should allow only aggregates
in non-distinct columns, like:
select distinct on date date, sum(bytes) from access_log;
If it does not, then it should be files as a bug imho.
-----------------
Hannu