Re: [PATCH] distinct aggregates within a window function WIP

On 4/21/20 5:06 PM, Eugen Konkov wrote:
> Hi. I read the thread.
>
> Probably this fiddle will be helpful for testing:
>
> https://dbfiddle.uk/?rdbms=postgres_12&fiddle=abe845142a5099d921d3729043fb8491
>
> I recently encountered a problem:
> Why Window-specific functions do not allow DISTINCT to be used within the function argument list?
>
> sum( DISTINCT order_cost ) OVER ( PARTITION BY invoice_id ORDER BY invoice_id, group_id RANGE unbound preceeding and unbound following )
>
> behavior is quite deterministic:
>
> ORDER BY will create peers in partition
> DISTINCT will get only one peer
>
> I resolve my problem via two subqueries, but it seems this logic may
> be applied to window functions (did not check this for other functions thought)

Sorry, I do not follow. What problem did you encounter?

Andreas