[FLINK-21165] Timestamps/Watermarks chained erroneously with previous operator

• Type: Bug
• Status: Open
• Priority: Not a Priority
• Resolution: Unresolved
• Affects Version/s: 1.11.1, 1.12.0
• Component/s: API / DataStream
• Labels: auto-deprioritized-major auto-deprioritized-minor
• Assignee: Unassigned
• Reporter: zlzhang0122
• Created: 27/Jan/21 12:44
• Updated: 06/Nov/21 22:38

Description

When using assignTimestampAndWatermarks function separately, if it can satisfied the chaining condition, it will chained erroneously with previous operator.

For example, I have a code like bellow: 

// code placeholder
DataStream<UserAction> ds = dataSource.map(xxx).setParallelism(1);

ds.assignTimestampAndWatermarks(xxxx);

DataStream<UserAction> rsStream = ds.keyBy(xxx).timeWindow(xxx).sum(xxx).setParallelism(2);

I will get the JobGraph bellow.

If I change my code to this:

// code placeholder
DataStream<UserAction> ds = dataSource.map(xxx).setParallelism(1); 

DataStream<UserAction> watermarkStream = ds.assignTimestampAndWatermarks(xxxx); 

DataStream<UserAction> rsStream = watermarkStream.keyBy(xxx).timeWindow(xxx).sum(xxx).setParallelism(2);

I will get the same JobGraph, at the same time the actual execution result is not the same.

I think the first JobGraph have some problem and should not show like that, maybe the Timestamps/Watermarks operator should show separately and should not chaining with previous operator.