private List<String> getChildrenFieldNames(PartitionFieldNode root) throws MetaException {
    List<String> childFields = new ArrayList<>(3);
    for (PartitionFieldNode child : root.getChildren()) {
      if (child.getFieldName().lastIndexOf(".") < 0) {
        throw new MetaException("Error parsing multi-valued field name " + child.getFieldName());
      }
      childFields.add(child.getFieldName().substring(child.getFieldName().lastIndexOf(".") + 1));
    }
    return childFields;
  }
Given a list of partition ids, returns the List of partially filled partitions based on the
projection list used to instantiate this PartitionProjectionEvaluator
@param partitionIds List of partition ids corresponding to the Partitions objects which are requested
@return Partitions where each partition has only the projected fields set
@throws MetaException
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/PartitionProjectionEvaluator.java