[CALCITE-4050] Traits Propagation for EnumerableMergeJoin Produces Incorrect Result

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.24.0
• Assignee: Unassigned
• Reporter: Jinpeng Wu
• Created: 08/Jun/20 07:04
• Updated: 25/Jul/20 15:00
• Resolved: 08/Jun/20 23:41

Description

In EnumerableMergeJoin's deriveTraits method, it uses a Map to record mapping from left keys to right keys (the keyMap variable). However, the left keys could have duplicate entries.
One example is JdbcTest.testJoinInCorrelatedSubQuery, the expected plan is

EnumerableProject(deptno=[$0], name=[$1], employees=[$2], location=[$3])
  EnumerableMergeJoin(condition=[AND(=($0, $5), =($0, $4))], joinType=[inner])
    EnumerableSort(sort0=[$0], dir0=[ASC])
      EnumerableTableScan(table=[[hr, depts]])
    EnumerableSort(sort0=[$1], sort1=[$0], dir0=[ASC], dir1=[ASC])
      ...

where left keys are [0, 0] , and right keys are [1, 0]. Deriving right child's traits may result in incorrect output.

Issue Links

• blocks: CALCITE-4052 Enable Top-down Optimization