Hi, You can see the field in AbstractStreamOperator
// We keep track of watermarks from both inputs, the combined input is the minimum // Once the minimum advances we emit a new watermark for downstream operators private long combinedWatermark = Long.MIN_VALUE; it will chose the Min watermark from the connect stream -- Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/