[jira] [Created] (CALCITE-7514) MultiJoinOptimizeBushyRule throws AssertionError when a join condition references 3 or more factors

["Sean Broeder (Jira)" <ji...@apache.org>]

Sean Broeder created CALCITE-7514:
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             Summary: MultiJoinOptimizeBushyRule throws AssertionError when a join condition references 3 or more factors
                 Key: CALCITE-7514
                 URL: https://issues.apache.org/jira/browse/CALCITE-7514
             Project: Calcite
          Issue Type: Bug
          Components: core
            Reporter: Sean Broeder
            Assignee: Sean Broeder


MultiJoinOptimizeBushyRule.onMatch builds a list of Edge objects from multiJoin.getJoinFilters() and assumes every edge connects exactly two factors. When a join condition references three or more factors — for
  example, a CASE expression that spans three tables — LoptMultiJoin.createEdge produces an edge whose factors.cardinality() is 3, causing an AssertionError in the edge comparator:

  java.lang.AssertionError: {0, 1, 2}
      at MultiJoinOptimizeBushyRule$1.rowCountDiff(MultiJoinOptimizeBushyRule.java:147)
      at MultiJoinOptimizeBushyRule$1.compare(MultiJoinOptimizeBushyRule.java:143)
      at MultiJoinOptimizeBushyRule.minPos(MultiJoinOptimizeBushyRule.java:347)
      at MultiJoinOptimizeBushyRule.chooseBestEdge(MultiJoinOptimizeBushyRule.java:329)
      at MultiJoinOptimizeBushyRule.onMatch(MultiJoinOptimizeBushyRule.java:157)

  The class Javadoc already acknowledges this as a known gap:

  * TODO:
  *   <li>Join conditions that touch 1 factor.
  *   <li>Join conditions that touch 3 factors.

This can be reproduced with the following query:
  SELECT e1.ename
  FROM emp e1, dept d, emp e2
  WHERE e1.deptno = d.deptno
    AND e2.deptno = d.deptno
    AND d.deptno = CASE WHEN e1.sal > 1000 THEN e2.empno ELSE e1.empno END

  With pre-program FILTER_INTO_JOIN (bottom-up) + JOIN_TO_MULTI_JOIN, the CASE condition spans all three factors and ends up in the MultiJoin's joinFilter. When MULTI_JOIN_OPTIMIZE_BUSHY fires, the assertion in
  rowCountDiff fails.

Expected behavior: The rule handles conditions that touch ≠ 2 factors gracefully, producing a valid join tree.

 Actual behavior: AssertionError at rowCountDiff (line 147), chooseBestEdge (line 329), or the edge-rewrite loop (line 244), depending on which assertion is reached first.




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