[FLINK-10978] Add FlatAggregate operator to batch Table API

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: Table SQL / API
• Labels: auto-unassigned
• Assignee: Unassigned
• Reporter: sunjincheng
• Created: 22/Nov/18 02:55
• Updated: 27/Apr/21 23:11

Description

Add FlatAggregate operator to batch Table API as described in Google doc .

The usage:

val res = tab
 .groupBy('a) // leave out groupBy-clause to define global table aggregates
 .flatAgg(fun: TableAggregateFunction)  // output has columns 'a, 'b, 'c
 .select('a, 'c)