X-czh commented on code in PR #25797: URL: https://github.com/apache/flink/pull/25797#discussion_r1903954648
########## docs/content/docs/dev/datastream/fault-tolerance/serialization/types_serialization.md: ########## @@ -167,6 +168,24 @@ input.keyBy(_.word) Flink supports all Java and Scala primitive types such as `Integer`, `String`, and `Double`. +#### Common Collection Types + +Since Flink 2.0, Flink comes with dedicated serialization support for common Java collection types, which is more efficient than going +through a general purpose serialization framework. Currently, only `Map`, `List`, `Set` and its super interface `Collection` +are supported. To utilize it, you need to declare the collection type with: + +1. Concrete type arguments: e.g. `List<String>` but not `List`, `List<T>`, or `List<?>`, as Flink needs them to dispatch + serialization of the element types. +2. Interface types: e.g. `List<String>` but not `LinkedList<String>`, as Flink does not preserve the underlying + implementation types across serialization. + +Other nonqualified collection types will be handled by Flink as general class types. If the implementation types are Review Comment: The serialized values are in bytes, so basically it is not human-readable, nor self-describing. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
