Github user StefanRRichter commented on a diff in the pull request: https://github.com/apache/flink/pull/5885#discussion_r183996477 --- Diff: flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBKeyedStateBackend.java --- @@ -1125,59 +1125,62 @@ private void restoreKeyGroupsShardWithTemporaryHelperInstance( * that we checkpointed, i.e. is already in the map of column families. */ @SuppressWarnings("rawtypes, unchecked") - protected <N, S> ColumnFamilyHandle getColumnFamily( + protected <N, S> Tuple2<ColumnFamilyHandle, RegisteredKeyedBackendStateMetaInfo<N, S>> getColumnFamilyAndStateSerializer( --- End diff -- I think this method has grown way too complex over time, and looking at the `Tuple2` return type it becomes more and more clear that this code is mixing up 2 different concerns and could be untangled a bit. I would suggest to separate this into: 1) checking if this is a new state (does the map contain the name string), this is like a inlined check in current calling code. 2) If yes, do the serializer checks and configuration magic and create the `RegisteredKeyedBackendStateMetaInfo`. this goes to a separate method that is called by the current caller. 3) Request the column family, either by new registration or the existing one. can use the result from step 1 or recheck. this goes in another separate method called by the current caller. x) Optional: helper method that does steps 1-3 if we otherwise duplicate them too much.
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