It's exciting to see TTL state cleanup feature in 1.8. I have a question regarding the migration of existing TTL state to the newer version.
Looking at the Pull Request [1] that introduced this feature, it seems like that Flink is leveraging RocksDB's compaction filter to remove stale state. I assume this means that state will only be cleaned on compaction. If I have a significant amount of stale TTL state, some of which may have already been compacted to higher levels already, upgrading to 1.8 may not clean them. Is this assumption correct? If so, is the best approach to take a full snapshot/checkpoint and restore it to 1.8 to have them been cleaned on initialization? Thanks, [1] https://github.com/dataArtisans/frocksdb/pull/1 -- Ning
