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  1. MariaDB Server
  2. MDEV-9999

Change the default value of optimizer_use_condition_selectivity

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    • Type: Task
    • Status: Closed (View Workflow)
    • Priority: Major
    • Resolution: Duplicate
    • Fix Version/s: N/A
    • Component/s: Optimizer
    • Labels:
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      Description

      Currently, the default for optimizer_use_condition_selectivity is 1

      https://mariadb.com/kb/en/mariadb/server-system-variables/#optimizer_use_condition_selectivity

      Meanings of values from here:

      1 Use selectivity of predicates as in MariaDB 5.5.
      2 Use selectivity of all range predicates supported by indexes.
      3 Use selectivity of all range predicates estimated without histogram.
      4 Use selectivity of all range predicates estimated with histogram.
      5 Additionally use selectivity of certain non-range predicates calculated on record sample.
      

      We could change the default to be 4. (This is not a big change as it may seem, because histograms are not collected automatically).

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              • Assignee:
                varun Varun Gupta
                Reporter:
                psergey Sergei Petrunia
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