Github user sihuazhou commented on a diff in the pull request: https://github.com/apache/flink/pull/5582#discussion_r191446989 --- Diff: flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBKeySerializationUtils.java --- @@ -138,4 +138,12 @@ private static void writeVariableIntBytes( value >>>= 8; } while (value != 0); } + + public static byte[] serializeKeyGroup(int keyGroup, int keyGroupPrefixBytes) { + byte[] startKeyGroupPrefixBytes = new byte[keyGroupPrefixBytes]; --- End diff -- Good point! There is one problem with this PR, After confirming with RocksDB the `deleteRange()` is still a experimental feature of RocksDB...even thought I did some experiments on this `deleteRange()` in our case, and I did find any downside, I'm not sure whether we should still use the `deleteRange()`, but the `deleteRange()` should be used for the recovery of the incremental checkpoint definitely when it's stable. What do you think?
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