Derby
  1. Derby
  2. DERBY-3314

RAND(SEED INTEGER) builtin function always returns the same random value for a given seed.

    Details

    • Type: Bug Bug
    • Status: Open
    • Priority: Minor Minor
    • Resolution: Unresolved
    • Affects Version/s: 10.3.1.4, 10.3.2.1, 10.4.1.3
    • Fix Version/s: None
    • Component/s: SQL
    • Urgency:
      Normal

      Description

      RAND or

      {fn RAND(seed)}

      exists to match the JDBC specification (section C.1)
      RAND(integer) Random floating point for seed integer

      Trouble is that Derby creates a new Random() instance for every call leading to the same return value for the same seed. Seems to be useful, the function should return a new random number even when handed the same seed.

      Some more specification is probably needed, when does a sequence based upon a seed start?

      • first call by any connection
      • sequence within a connection
      • sequence within a sql context (e.g. procedure call, statement etc.)

      Also need to be wary of memory leaks if the engine needs to hold onto Random objects beyond the lifetime of the RAND call.

      ij> values rand(3);
      1
      ----------------------
      0.731057369148862

      1 row selected
      ij> values rand(3);
      1
      ----------------------
      0.731057369148862

      1 row selected
      ij> values

      {fn rand(3)}

      ;
      1
      ----------------------
      0.731057369148862

      1 row selected

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            • Assignee:
              Unassigned
              Reporter:
              Daniel John Debrunner
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              Dates

              • Created:
                Updated:

                Development