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  1. MariaDB ColumnStore
  2. MCOL-4004

Reduce computation complexity of group_concat()

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    Details

    • Type: New Feature
    • Status: Open (View Workflow)
    • Priority: Minor
    • Resolution: Unresolved
    • Affects Version/s: 1.5
    • Fix Version/s: 5.7.1
    • Component/s: ExeMgr
    • Labels:
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      Description

      As of 1.5 group_concat tries to precisely calculate the length of a result string elements. This is waistfull thus we should employ an heuristic,e.g. all of the elements takes 75% of the maximum length for the datatype.
      We can compare the resulting string length with the allowed maximum length in ::getResult(). The refactoring is partially done(for DECIMALS) in MCOL-641.
      Given this approach the estimate should be also calculated only once given we know RowGroup size.

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            Assignee:
            toddstoffel Todd Stoffel
            Reporter:
            drrtuy Roman
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              Dates

              Created:
              Updated: