There is a bug in FullOuter and RightOuter Join mode!

[aminakov]

Just do that code and see both 1 and 2 steps.

In step 1. you can see 2 values in ww Table instead of 1 (which you can see in Source step. 

In step 2. you can still see row with null valiues, despite the filter for not null values.

That's a relation - fundamental function for data handling, please fix the bug urgently!

let
    Source = Table.NestedJoin(Table.Buffer(#table(type table [k = number, w = text], {{1, "w"}, {2, "w"}})), {"k"}, Table.Buffer(#table(type table [k = number, w = text], {{2, "k"}, {4, "w"}})), {"k"}, "ww", JoinKind.FullOuter),
    #"1.Zombie Values if filter Null" = Table.SelectRows(Source, each ([w] = null)), 
    #"2.Zombie Null Rows when filter not null" = Table.SelectRows(Source, each ([w] <> null))
in 
    #"2.Zombie Null Rows when filter not null"

[v-chuncz-msft]

@aminakov 

You may try to change it as follows.

Source = Table.Buffer(Table.NestedJoin

[aminakov]

I can do Table.AddIndexColumn, but please could you say when you fix the bug?

And could you say why Table.AddIndexColumn solves the problem? I understand why Table.Buffer does that, but not undestand why Table.AddIndexColumn helps.