Uploaded image for project: 'Derby'
  1. Derby
  2. DERBY-6127

Tell users to make sure that the state of a user-defined aggregate needs to be serializable

    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 10.10.1.1
    • Fix Version/s: 10.10.2.0, 10.11.1.1
    • Component/s: Documentation
    • Labels:
      None

      Description

      The Reference Manual section on "CREATE DERBY AGGREGATE statement" should tell users to make sure that all of the state of their user-defined aggregate is really serializable. This is because the Aggregator interface extends java.io.Serializable. A user-defined aggregate may end up being serialized to disk when performing grouped aggregation over a large number of groups. That is, intermediate results may be serialized to disk for a query like the following. The serialization will fail if the user-defined aggregate contains non-serializable fields:

      select a, myAggregate( b ) from myTable group by a

        Attachments

        1. DERBY-6127.zip
          5 kB
          Kim Haase
        2. DERBY-6127.stat
          0.1 kB
          Kim Haase
        3. DERBY-6127.diff
          3 kB
          Kim Haase

          Issue Links

            Activity

              People

              • Assignee:
                chaase3 Kim Haase
                Reporter:
                rhillegas Rick Hillegas
              • Votes:
                0 Vote for this issue
                Watchers:
                4 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved: