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      <a name="controlling-optimizer">
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      10.9 Controlling the Query Optimizer
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    <dt>
     <span class="section">
      <a href="controlling-query-plan-evaluation.html">
       10.9.1 Controlling Query Plan Evaluation
      </a>
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    </dt>
    <dt>
     <span class="section">
      <a href="switchable-optimizations.html">
       10.9.2 Switchable Optimizations
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     <span class="section">
      <a href="optimizer-hints.html">
       10.9.3 Optimizer Hints
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    <dt>
     <span class="section">
      <a href="index-hints.html">
       10.9.4 Index Hints
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    <dt>
     <span class="section">
      <a href="cost-model.html">
       10.9.5 The Optimizer Cost Model
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      <a href="optimizer-statistics.html">
       10.9.6 Optimizer Statistics
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  <p>
   MySQL provides optimizer control through system variables that
      affect how query plans are evaluated, switchable optimizations,
      optimizer and index hints, and the optimizer cost model.
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  <p>
   The server maintains histogram statistics about column values in
      the
   <code class="literal">
    column_statistics
   </code>
   data dictionary table
      (see
   <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics">
    Section 10.9.6, “Optimizer Statistics”
   </a>
   ). Like other data
      dictionary tables, this table is not directly accessible by users.
      Instead, you can obtain histogram information by querying
   <a class="link" href="information-schema-column-statistics-table.html" title="28.3.11 The INFORMATION_SCHEMA COLUMN_STATISTICS Table">
    <code class="literal">
     INFORMATION_SCHEMA.COLUMN_STATISTICS
    </code>
   </a>
   ,
      which is implemented as a view on the data dictionary table. You
      can also perform histogram management using the
   <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement">
    <code class="literal">
     ANALYZE TABLE
    </code>
   </a>
   statement.
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