Github user tzulitai commented on a diff in the pull request: https://github.com/apache/flink/pull/5885#discussion_r184694977 --- Diff: flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBKeyedStateBackend.java --- @@ -1116,148 +1115,177 @@ private void restoreKeyGroupsShardWithTemporaryHelperInstance( // ------------------------------------------------------------------------ /** - * Creates a column family handle for use with a k/v state. When restoring from a snapshot - * we don't restore the individual k/v states, just the global RocksDB database and the - * list of column families. When a k/v state is first requested we check here whether we - * already have a column family for that and return it or create a new one if it doesn't exist. + * Registers a k/v state information, which includes its state id, type, RocksDB column family handle, and serializers. * - * <p>This also checks whether the {@link StateDescriptor} for a state matches the one - * that we checkpointed, i.e. is already in the map of column families. + * When restoring from a snapshot, we donât restore the individual k/v states, just the global RocksDB database and + * the list of k/v state information. When a k/v state is first requested we check here whether we + * already have a registered entry for that and return it (after some necessary state compatibility checks) + * or create a new one if it does not exist. */ - @SuppressWarnings("rawtypes, unchecked") - protected <N, S> ColumnFamilyHandle getColumnFamily( - StateDescriptor<?, S> descriptor, TypeSerializer<N> namespaceSerializer) throws IOException, StateMigrationException { + private Tuple2<ColumnFamilyHandle, RegisteredKeyedBackendStateMetaInfo<?, ?>> tryRegisterKvStateInformation( --- End diff -- I did not go with this approach because of the extra tuples introduced. Though, TBH, I wasn't sure which was the better approach, this or the one you pointed out. I would not be against this version.
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