Oleks V

> > I don't know of anyone working on it @Tangruilin -- I have assigned it to you; As @comphead says, this is probably a task that needs some design...

Moving to draft as it is expected more actions before PR can be finally reviewed

Related to #6108

looking fwd for the PR :)

Weird thing, it might be a bigger problem behind ``` DataFusion CLI v36.0.0 ❯ select lag(a) over () as x1 from (select 2 id, 'b' a union all select 1...

> > lgtm thanks @andygrove I think in followup we will put this check separately into its own CI task, what do you think? > > Hi @comphead. Are you...

@sunchao @viirya cc

@alamb are we okay to support such syntax in DF? ``` select first_value(a) ignore nulls over (partition by id order by id) from (select 1 id, 'a' a union all...

Thanks @viirya Looks like currently the DF is able to parse the SQL 2016 standard syntax for this specific case, so it is probably worth to try implementing IGNORE NULLS...

It seems there is no defined opinion yet, I'll create a PR and we can discuss in details