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  1. HPCC
  2. HPCC-9763

Use flag generated by UNORDERED on a standard join

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    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 4.0.2
    • Component/s: Thor
    • Labels:
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      Description

      There are HINT's that can be supplied to a standard join, to tell it to use a multi threaded helper to match groups in parallel. Another HINT tells it, it can output the results unordered. In combination this can significantly speed up expensive join group matching.

      The code generator assumes aspects about the order of the join output, e.g. that a lightweight join will have it's output in sorted order or that a lookup join will preserve the order of the LHS.
      The HINT's change the order without the code generator's knowledge.

      This reordering should be explicit via a ECL flag.
      There is already a UNORDERED keyword, but it doesn't generate a flag.

      So:
      a) Generate the flag for engines to pick up
      b) Get Thor to use the flag in preference to HINT.

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            Assignee:
            jakesmith Jake Smith
            Reporter:
            jakesmith Jake Smith
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              Updated:
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