Re: Re: Request for Patch Feedback: Lag & Lead Window Functions Can Ignore Nulls

Old thread link:
http://www.postgresql.org/message-id/CA+=vxNa5_N1q5q5OkxC0aQnNdbo2Ru6GVw+86wk+oNsUNJDLig@mail.gmail.com

On Thu, Apr 14, 2016 at 1:29 PM, Stephen Frost <sfrost@snowman.net> wrote:
> Jeff
>
> (Reviving an old thread for 2014...)

>
> Would you have time to work on this for 9.7..?  I came across a
> real-world use case for exactly this capability and was sorely
> disappointed to discover we didn't support it even though there had been
> discussion for years on it, which quite a few interested parties.
> 

First, I think the syntax is still implemented in a bad way. Right now
it's part of the OVER clause, and the IGNORE NULLS gets put into the
frame options. It doesn't match the way the spec defines the grammar,
and I don't see how it really makes sense that it's a part of the
frame options or the window object at all.

I think we need a need catalog support to say
whether a function honors IGNORE|RESPECT NULLS or not, which means we
also need support in CREATE FUNCTION.