@Override
  public Stream<Pair<byte[], byte[]>> streamFromKey(
      final SegmentIdentifier segment, final byte[] startKey) {
    throwIfClosed();

    final RocksIterator rocksIterator =
        db.newIterator(columnFamilyMapper.apply(segment), readOptions);
    rocksIterator.seek(startKey);
    return RocksDbIterator.create(rocksIterator).toStream();
  }
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