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

["Danny Chan (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-2927?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Danny Chan closed CALCITE-2927.
-------------------------------
    Resolution: Not A Bug

> 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
>            Priority: Minor
>              Labels: pull-request-available
>             Fix For: next
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> 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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