[CALCITE-3211] List of MutableRel may fail to be identified by SubstitutionVisitor during matching

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.21.0
• Labels: pull-request-available
• Assignee: Unassigned
• Reporter: Jin Xing
• Created: 25/Jul/19 08:09
• Updated: 10/Sep/19 21:36
• Resolved: 31/Jul/19 07:17

Description

Current implementation of MutableRels::toMutables is as below:

  private static List<MutableRel> toMutables(List<RelNode> nodes) {
    return Lists.transform(nodes, MutableRels::toMutable);
  }

Thus every time we get from the result list, a new MutableRel will be created:

  private static class TransformingRandomAccessList<F, T> extends AbstractList<T>
      implements RandomAccess, Serializable {
    final List<F> fromList;
    final Function<? super F, ? extends T> function;

    TransformingRandomAccessList(List<F> fromList, Function<? super F, ? extends T> function) {
      this.fromList = checkNotNull(fromList);
      this.function = checkNotNull(function);
    }

    @Override
    public T get(int index) {
      return function.apply(fromList.get(index));
    }
......

As a result, https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/plan/SubstitutionVisitor.java#L514 SubstitutionVisitor will fail to check whether a node has been met/matched before

Issue Links

• links to: GitHub Pull Request #1330