@Override
  public Stream<byte[]> streamKeys(final SegmentIdentifier segment) {
    throwIfClosed();

    final RocksIterator rocksIterator =
        db.newIterator(columnFamilyMapper.apply(segment), readOptions);
    rocksIterator.seekToFirst();
    return RocksDbIterator.create(rocksIterator).toStreamKeys();
  }
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