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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

    • 2021-7, 2021-8, 2021-9, 2021-10, 2021-11, 2021-12

    Description

      First pointed out by Quinnstreet, now confirmed by drrtuy. 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. drrtuy 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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        Issue Links

          is blocked by

          Task - A task that needs to be done. MCOL-4791 Fix ColumnCommand fudged data type format to clearly identify CHAR vs VARCHAR

          • Major - Major loss of function.
          • Stalled

          Task - A task that needs to be done. MCOL-4801 Replace Row methods getStringLength() and getStringPointer() to getConstString()

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Task - A task that needs to be done. MDEV-26572 Improve simple multibyte collation performance on the ASCII range

          • Major - Major loss of function.
          • Closed
          relates to

          Task - A task that needs to be done. MCOL-2000 varchar specified sizing is not in characters

          • Major - Major loss of function.
          • Closed

          New Feature - A new feature of the product, which has yet to be developed. MCOL-5043 Reduce a number of pre-spawned ExeMgr threads

          • Major - Major loss of function.
          • Stalled

          New Feature - A new feature of the product, which has yet to be developed. MCOL-5044 Improve PP thread pool with a fair scheduler

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MCOL-4593 Multiple concurrent queries with aggregates are bottlenecked, result in lack of user scalability

          • Trivial - Cosmetic problem like misspelt words or misaligned text.
          • Stalled

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            People

              leonid.fedorov Leonid Fedorov
              gdorman Gregory Dorman (Inactive)
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              Dates

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                Updated:
                Resolved:

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