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  1. MariaDB Server
  2. MDEV-204

Use the statistics from persistent statistical tables instead of the statistics provided by engine (MWL#250)

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    Details

    • Type: Task
    • Status: Closed (View Workflow)
    • Priority: Major
    • Resolution: Duplicate
    • Fix Version/s: None
    • Component/s: None
    • Labels:
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      Description

      This task adds the functionality that allows optionally to use use the
      statistics from persistent statistical tables [1] instead of the
      statistics provided by engine.

      It will allow

      • to have stable execution plans (with InnoDB) in mysql-test
      • to run DBT-3 benchmark (for InnoDB) without any hassle due to instability in chosen execution plans
      • to repeat bugs reported by users, that are triggered by a specific query plan and sensitive to statistics.
        • for this to work, it should be possible to populate statistical tables from the output of SHOW INDEX or have some other way of getting the statictics from a user.
      • to implement any statstics that we need, without requiring engines to support it natively. For example, we can store the cardinality for non-indexed columns. Or correlations between two columns.
      • to have identical plans on the master and on the slave
      • to avoid "eight random dives" of InnoDB, that are considered expensive
      • to have adequate statistics and query plans immediately after server startup, without (possibly long) warm-up time

      [1] http://askmonty.org/worklog/?tid=250

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              Assignee:
              igor Igor Babaev
              Reporter:
              igor Igor Babaev
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                Updated:
                Resolved:

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