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  1. MariaDB ColumnStore
  2. MCOL-4527 Simple query performace is degraded between 5.4 and 5.5
  3. MCOL-4528

Analyze and explain the reasons for the difference between 5.4 and 5.5

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    Details

    • Type: Sub-Task
    • Status: Closed (View Workflow)
    • Priority: Major
    • Resolution: Done
    • Affects Version/s: None
    • Fix Version/s: 5.5.2
    • Component/s: N/A
    • Labels:
      None
    • Sprint:
      2021-2, 2021-3

      Description

      Basic facts as known today:

      • Available traces show 2x elapsed time between 5.4 and 5.5
      • They also show 50% difference in LIO
      • This is almost certainly NOT extent elimination problem. The reason for this statement is that when this query was run using utf8, it did not do extent elimination, and the difference was close to 4x on elapsed and 3x on LIO.
      • Personal opinions point to CPU overhead of collations. But before this is positively determined - the difference in LIO needs to be explaind.
        REPEAT: this task is RESEARCH and diagnosis only. No solutions are to be proposed at this time.

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            Assignee:
            David.Hall David Hall
            Reporter:
            gdorman Gregory Dorman
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              Dates

              Created:
              Updated:
              Resolved:

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