Hi there, It looks like Flink does not support fields containing a dot character in the watermark.
The validation done on Flink code to determine whether the property is "nested", is to check if they contain a dot in the name, so even if the property is not nested, but contains a dot, it is reported as not valid: https://github.com/apache/flink/blob/master/flink-table/flink-table-planner/src/main/java/org/apache/flink/table/planner/connectors/DynamicSourceUtils.java#L604-L609 If we were to remove this check, are there other reasons why watermarks cannot be based on a nested field? Ideally we would actually like to run with watermarks based on nested fields. WDYT? Kind regards, David. Unless otherwise stated above: IBM United Kingdom Limited Registered in England and Wales with number 741598 Registered office: PO Box 41, North Harbour, Portsmouth, Hants. PO6 3AU