Re: FILTER clause for non-aggregate window functions

Андрей Жиденков <[email protected]> Tue, 12 Dec 2017 19:53:01 +0300

Newsgroups	gmane.comp.db.postgresql.sql
Message-ID	<CAN=gQ4Aa5i16eWC_UgsPswpMBsVy6Pshvmq76E=Y4gk98OLg8A@mail.gmail.com>

I could not put the restrictions in WHERE because I want them to be applied
only to the window frame, not to all selected rows.

On 12 Dec. 2017 18:35, "Tom Lane" <[email protected]> wrote:

> =?UTF-8?B?0JDQvdC00YDQtdC5INCW0LjQtNC10L3QutC+0LI=?= <[email protected]>
> writes:
> > Why FILTER is not implemented for non-aggregate functions?
>
> The SQL standard only describes FILTER for aggregates.  I'm not sure
> offhand whether it'd be semantically sensible for window functions.
> In any case, seems like most of the cases where you'd want it can be
> expressed equally well by putting the restriction into WHERE.
>
>                         regards, tom lane
>