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  1. MariaDB ColumnStore
  2. MCOL-1882

Aggregates performance degradation between 1.1 and 1.2

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    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Major
    • Resolution: Duplicate
    • Affects Version/s: 1.2.1
    • Fix Version/s: Icebox
    • Component/s: PrimProc
    • Labels:
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      Description

      There is a major performance degradation between 1.2 and 1.1. Here is the test bed.

      MariaDB [test]> desc t1;
      +-------+--------+------+-----+---------+-------+
      | Field | Type   | Null | Key | Default | Extra |
      +-------+--------+------+-----+---------+-------+
      | a     | double | YES  |     | NULL    |       |
      | b     | double | YES  |     | NULL    |       |
      +-------+--------+------+-----+---------+-------+
      2 rows in set (0.00 sec)
      MariaDB [test]> select count(*) from t1;
      +-----------+
      | count(*)  |
      +-----------+
      | 560023752 |
      +-----------+
      1 row in set (2.46 sec)
      

      Version 1.1 timings for the query

      MariaDB [test]> select max(a),max(b) from t1;
      selec count(*) from t1;
      +--------+--------+
      | max(a) | max(b) |
      +--------+--------+
      |      1 |      1 |
      +--------+--------+
      1 row in set (14.66 sec)
      

      1.2 timings for the query with the same hardware, standart lib, boost

      MariaDB [test]> select max(a),max(b) from t1;
      selec count(*) from t1;
      +--------+--------+
      | max(a) | max(b) |
      +--------+--------+
      |      1 |      1 |
      +--------+--------+
      1 row in set (27.53 sec)
      

      According with the assembly transcript of the code the problem caused by excesive locking for atomic ref counter increase whilst running shared_pointer copy constructor in rowaggregation.cpp by RowAggregation::updateEntry().

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              Assignee:
              LinuxJedi Andrew Hutchings (Inactive)
              Reporter:
              drrtuy Roman
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                Dates

                Created:
                Updated:
                Resolved:

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