[FLINK-22314] AggRecordsCombiner should combine buffered records first instead of accumulate on state directly

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Component/s: Table SQL / Runtime
• Assignee: Jark Wu
• Reporter: Jark Wu
• Created: 16/Apr/21 12:15
• Updated: 17/Apr/21 14:42
• Resolved: 17/Apr/21 14:42

Description

In Window TVF Aggregation, currently, the AggRecordsCombiner accumulates buffered records on state directly. This is not good for performance. We can accumulate records in memory first, and then merge the accumulator into state, if the aggs support merge() method. This can reduce lots of state accessing when having COUNT DISTINCT.