Github user greghogan commented on a diff in the pull request:
https://github.com/apache/flink/pull/4574#discussion_r139184023
--- Diff: docs/dev/types_serialization.md ---
@@ -115,6 +115,8 @@ conditions are fulfilled:
or have a public getter- and a setter- method that follows the Java beans
naming conventions for getters and setters.
+Note that when a data type can't be recognized as a POJO type, it will be
handled as GenericType.
--- End diff --
"... it will be processed as a GenericType and serialized with Kryo"? Is it
generally understood that use of Kryo can have a significant impact on
performance? It's not just serialization which is slower. It looks like if the
class does not implement `NormalizedKey` then objects are deserialized for each
comparison.
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