Details
-
Improvement
-
Status: Reopened
-
Not a Priority
-
Resolution: Unresolved
-
1.2.1, 1.3.0
-
None
-
None
Description
Placing timestamp assignment (and watermark generation) directly or indirectly after a union is generally not desirable as it may lead to surprising results at the client side. Ideally, timestamp assignment (and watermark generation) is best placed as close as possible to the data sources. It would be nice to generate a warning to the user (i.e. to the log) before job execution if the framework detects timestamp assignment (directly or indirectly placed) after a union.
Some more background information for this issue can be found in this email thread: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/union-followed-by-timestamp-assignment-watermark-generation-td13036.html