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  1. MariaDB ColumnStore
  2. MCOL-4691

Major Regression: Selects with aggregates 2x slower in 5.x than in 1.2 (due to collation support)

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    Details

    • Type: Bug
    • Status: Open (View Workflow)
    • Priority: Critical
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: 23.08
    • Component/s: None
    • Labels:
    • Sprint:
      2021-7, 2021-8, 2021-9, 2021-10, 2021-11, 2021-12

      Description

      First pointed out by Quinnstreet, now confirmed by Roman. This requires profiling in both releases and identification of where the extra time is eaten.

      While it also shows lack of user scaling in both releases, that part is not the focus of this ticket (there is related ticket for that). This one is only about raw difference between releases. Roman has the environment and a reproduction.

      tail_num is VARCHAR(6). The table's charset is utf8.

      In 1.2 tests

      root@ip-172-31-23-117:/data/slapit#  ./sysbench_series.sh  slap4.lua
      select s from (select count(*) as s from flights group by tail_num)sub;
      #users                                        Average time
      1          avg:                                133.84
      2          avg:                                141.78
      3          avg:                                175.30
      4          avg:                                215.92
      5          avg:                                251.24
      6          avg:                                281.05
      7          avg:                                327.09
      8          avg:                                366.62
      9          avg:                                411.97
      10          avg:                                456.93
      11          avg:                                506.55
      

      in 5.2.2 tests

      select s from (select count(*) as s from flights group by tail_num)sub;
      root@ip-172-31-3-254:/data/slapit# ./sysbench_series.sh slap4.lua
      1          avg:                                  381.95
      2          avg:                                  284.49
      3          avg:                                  336.59
      4          avg:                                  427.69
      5          avg:                                  527.38
      6          avg:                                  622.61
      7          avg:                                  720.63
      8          avg:                                  830.55
      9          avg:                                  927.50
      10          avg:                                 1032.59
      

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              Assignee:
              alexey.vorovich alexey vorovich
              Reporter:
              gdorman Gregory Dorman
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                Dates

                Created:
                Updated:

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