Re: [PATCH] distinct aggregates within a window function WIP - Mailing list pgsql-hackers

From Eugen Konkov
Subject Re: [PATCH] distinct aggregates within a window function WIP
Date
Msg-id 186624638.20200422100519@yandex.ru
Whole thread Raw
In response to Re: [PATCH] distinct aggregates within a window function WIP  (Andreas Karlsson <andreas@proxel.se>)
Responses Re: [PATCH] distinct aggregates within a window function WIP  (Eugen Konkov <kes-kes@yandex.ru>)
List pgsql-hackers
Hello Andreas,

Tuesday, April 21, 2020, 6:17:00 PM, you wrote:

> 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
unboundfollowing )
 
>> 
>> 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?

Lack of DISTINCT for window function SUM



-- 
Best regards,
Eugen Konkov




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