Derby
  1. Derby
  2. DERBY-649 Useful indexes not used in UNION ALL
  3. DERBY-772

Handle pushing IN predicates into UNIONs. This would allow use of index if present improving performance.

    Details

    • Type: Sub-task Sub-task
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: 10.0.2.0, 10.1.2.1, 10.2.1.6
    • Fix Version/s: 10.1.3.1, 10.2.1.6
    • Component/s: SQL
    • Labels:
      None
    • Environment:
      generic

      Description

      While fix for DERBY-649 allows pushing binary predicates into SELECT statements that are underneath a UNOIN, it would also be good to allow IN operations to be pushed. Derby can rewrite IN operations in a way to allow use of index, if present.

      Derby currently rewrites: REF IN (1, 2, 3) to REF >=1 and REF <=3 and hence would allow use of index on REF, if present. Pushing this predicate into Union would allow use of index on REF for queries like:

      Select * from
      (SELECT REF, NAME from T1 UNION ALL SELECT REF, NAME from t2)
      where REF IN (1,2,3)

      1. DERBY-772.patch
        22 kB
        Satheesh Bandaram

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          • Assignee:
            Unassigned
            Reporter:
            Satheesh Bandaram
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            Dates

            • Created:
              Updated:
              Resolved:

              Development