@Override
        protected Bytes getBaseKey(final Bytes indexKey) {
            final Window window = KeyFirstSessionKeySchema.extractWindow(indexKey.get());
            final byte[] key = KeyFirstSessionKeySchema.extractKeyBytes(indexKey.get());

            return TimeFirstSessionKeySchema.toBinary(Bytes.wrap(key), window.start(), window.end());
        }
A RocksDB backed time-ordered segmented bytes store for session key schema.
streams/src/main/java/org/apache/kafka/streams/state/internals/RocksDBTimeOrderedSessionSegmentedBytesStore.java