[FLINK-3614] Remove Non-Keyed Window Operator

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.1.0
• Component/s: API / DataStream
• Assignee: Aljoscha Krettek
• Reporter: Aljoscha Krettek
• Created: 15/Mar/16 10:01
• Updated: 28/Feb/19 11:15
• Resolved: 05/Apr/16 15:21

Description

I propose to remove the special Non-Keyed Window Operator and implement non-parallel windows by using the standard WindowOperator with a dummy KeySelector.

Maintaining everything for two WindowOperators is a huge burden. The implementation is completely separate by now. For example, the Non-Keyed window operator does not use the StateBackend for state, i.e. cannot use RocksDB. Also, with upcoming changes (Merging/Session windows, aligned windows) this will only increase the maintenance burden.

Also, the fast AlignedProcessingTimeWindows operators also only support the Parallel/Keyed case.