/** Collects all the StarTree leaves that match the provided dimension values */
 private void findMatchingLeaves(
     StarTreeIndexNode node, List<Integer> values, Set<StarTreeIndexNode> leaves) {
   if (node.isLeaf()) {
     leaves.add(node);
   } else {
     Integer value = values.get(node.getChildDimensionName());
     findMatchingLeaves(node.getChildren().get(value), values, leaves);
     findMatchingLeaves(node.getChildren().get(StarTreeIndexNode.all()), values, leaves);
   }
 }
  /**
   * Returns the unique metric values for each column.
   *
   * <p>The original unique values cannot be used because after aggregation, we almost certainly
   * have new values to encode that were not present in the original data set.
   */
  private Map<String, Set<Object>> computeUniqueMetricValues() {
    Map<String, Set<Object>> uniqueMetricValues = new HashMap<String, Set<Object>>();

    Iterator<StarTreeTableRow> tableIterator = starTreeBuilder.getTable().getAllCombinations();
    while (tableIterator.hasNext()) {
      StarTreeTableRow row = tableIterator.next();

      for (int i = 0; i < schema.getMetricNames().size(); i++) {
        String metricName = schema.getMetricNames().get(i);
        Object metricValue = row.getMetrics().get(i);
        Set<Object> uniqueValues = uniqueMetricValues.get(metricName);
        if (uniqueValues == null) {
          uniqueValues = new HashSet<Object>();
          uniqueMetricValues.put(metricName, uniqueValues);
        }
        uniqueValues.add(metricValue);
      }
    }

    return uniqueMetricValues;
  }