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Dawid Wysakowicz commented on FLINK-2971:
-----------------------------------------
Thanks for assigning me to this issue. I've started working on it, but I
encountered a problem I wanted to discuss. I wanted to enhance {{Table}} with
methods like:
{code}
def join(right: Table): Table
def join(right: Table, onColumns: String): Table
def join(right: Table, onColumns: Expression): Table
def join(right: Table, onColumns: Expression, joinType: JoinType): Table
{code}
Those method enable users to specify join condition and joinType (join
condition pushed from {{filter}} or {{where}} disables the outer joins).
Unfortunately right know it is impossible to resolve
{{UnresolvedFieldReference}} to a field of one of many inputs. I proposed a
solution(table.scala:437-447), but I am not sure if it is elegant enough.
My WIP branch: https://github.com/dawidwys/flink/tree/outerJoin
> Add outer joins to the Table API
> --------------------------------
>
> Key: FLINK-2971
> URL: https://issues.apache.org/jira/browse/FLINK-2971
> Project: Flink
> Issue Type: New Feature
> Components: Table API
> Reporter: Timo Walther
> Assignee: Dawid Wysakowicz
>
> Since Flink now supports outer joins, the Table API can also support left,
> right and full outer joins.
> Given that null values are properly supported by RowSerializer etc.
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