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  1. Calcite
  2. CALCITE-41

Add rule to propagate constraints onto aliased columns

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Duplicate
    • Affects Version/s: None
    • Fix Version/s: 0.9.0-incubating
    • Component/s: None
    • Labels:

      Description

      Consider:

      SELECT *
      FROM emp JOIN dept ON emp.deptno = dept.deptno
      WHERE emp.deptno = 10

      Clearly we can push down "emp.deptno = 10" through the join. But we can also generate a constraint "dept.deptno = 10" on the other input to the join. This task is to add a rule to achieve that.

      The rule would propagate the constraints on column "a" onto column "b" when "a" and "b" are compared using "=" or other relational operator (e.g. ">") in a filter or join condition.

      The planner state should reflect the fact that such constraints are optional – i.e. the query produces the same result if the constraints are omitted – and therefore the constraints can be omitted if they turn out to be expensive to implement.

      ---------------- Imported from GitHub ----------------
      Url: https://github.com/julianhyde/optiq/issues/41
      Created by: julianhyde
      Labels:
      Created at: Fri May 17 01:13:26 CEST 2013
      State: open

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              • Assignee:
                julianhyde Julian Hyde
                Reporter:
                github-import GitHub Import
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