presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/metadata/ShardIterator.java/ShardIterator/fetchNode
class ShardIterator:    private String fetchNode(int id, UUID shardUuid)
    {
        String node = dao.getNodeIdentifier(id);
        if (node == null) {
            throw new PrestoException(RAPTOR_ERROR, format("Missing node ID [%s] for shard: %s", id, shardUuid));
        }
        return node;
    }