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  1. Derby
  2. DERBY-4977

XPLAIN reports negative EXECUTE_TIME for some parts of a join

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Minor
    • Resolution: Unresolved
    • Affects Version/s: 10.7.1.1
    • Fix Version/s: None
    • Component/s: SQL
    • Urgency:
      Low
    • Issue & fix info:
      Repro attached

      Description

      I see that if I execute a join against the system tables with XPLAIN and statistics timing enabled, some of the rows in SYSXPLAIN_RESULTSET_TIMINGS have negative values in the EXECUTE_TIME column.

      Here are the contents of the SYSXPLAIN_RESULTSET_TIMINGS after two runs with the attached repro script:

      ij> select execute_time from my_schema.sysxplain_resultset_timings;
      EXECUTE_TIME
      --------------------
      -1
      0
      0
      -6
      9
      16

      6 rows selected

      ij> select execute_time from my_schema.sysxplain_resultset_timings;
      EXECUTE_TIME
      --------------------
      -1
      1
      0
      -7
      10
      15

      6 rows selected

      Note the two rows with negative values in both of the examples.

        Attachments

        1. timing.sql
          0.5 kB
          Knut Anders Hatlen

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            People

            • Assignee:
              Unassigned
              Reporter:
              knutanders Knut Anders Hatlen
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              Dates

              • Created:
                Updated: