private static Bytes makeCacheKey(final byte[] segmentId, final byte[] key) {
    final byte[] combined = new byte[segmentId.length + key.length];
    System.arraycopy(segmentId, 0, combined, 0, segmentId.length);
    System.arraycopy(key, 0, combined, segmentId.length, key.length);
    return Bytes.wrap(combined);
  }
Instantiates a new RocksDb columnar key value snapshot.

@param db the db
@param metrics the metrics
plugins/rocksdb/src/main/java/org/hyperledger/besu/plugin/services/storage/rocksdb/segmented/RocksDBColumnarKeyValueSnapshot.java