[jira] [Created] (CALCITE-2927) The javadoc and implement of RuleQueue.computeImportance() is inconsistent

["Meng Wang (JIRA)" <ji...@apache.org>]

Meng Wang created CALCITE-2927:
----------------------------------

             Summary: The javadoc and implement of RuleQueue.computeImportance() is inconsistent
                 Key: CALCITE-2927
                 URL: https://issues.apache.org/jira/browse/CALCITE-2927
             Project: Calcite
          Issue Type: Bug
          Components: core
    Affects Versions: 1.18.0
            Reporter: Meng Wang
             Fix For: next


In the javadoc of _computeImportance()_, it shows the importance of node is Sum{_computeImportanceOfChild()_}, but in the implementation it shows Max{_computeImportanceOfChild()_}, this is inconsistent. The Javadoc has some errors, it will cause some confusion.

 
{code:java}
// /**
 * Computes the <dfn>importance</dfn> of a node. Importance is defined as
 * follows:
 *
 * <ul>
 * <li>the root {@link RelSubset} has an importance of 1</li>
 * <li>the importance of any other subset is the sum of its importance to
 * its parents</li>
 * <li>The importance of children is pro-rated according to the cost of the
 * children. Consider a node which has a cost of 3, and children with costs
 * of 2 and 5. The total cost is 10. If the node has an importance of .5,
 * then the children will have importance of .1 and .25. The retains .15
 * importance points, to reflect the fact that work needs to be done on the
 * node's algorithm.</li>
 * </ul>
 *
 * <p>The formula for the importance <i>I</i> of node n is:
 *
 * <blockquote>I<sub>n</sub> = Sum<sub>parents p of n</sub>{I<sub>p</sub> .
 * W <sub>n, p</sub>}</blockquote>
 *
 * <p>where W<sub>n, p</sub>, the weight of n within its parent p, is
 *
 * <blockquote>W<sub>n, p</sub> = Cost<sub>n</sub> / (SelfCost<sub>p</sub> +
 * Cost<sub>n0</sub> + ... + Cost<sub>nk</sub>)
 * </blockquote>
 */
double computeImportance(RelSubset subset) {
  double importance;
  if (subset == planner.root) {
    // The root always has importance = 1
    importance = 1.0;
  } else {
    final RelMetadataQuery mq = subset.getCluster().getMetadataQuery();

    // The importance of a subset is the max of its importance to its
    // parents
    importance = 0.0;
    for (RelSubset parent : subset.getParentSubsets(planner)) {
      final double childImportance =
          computeImportanceOfChild(mq, subset, parent);
      importance = Math.max(importance, childImportance);
    }
  }
  LOGGER.trace("Importance of [{}] is {}", subset, importance);
  return importance;
}
{code}
 

 



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