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     <h2 class="title">
      <a name="data-dictionary-transactional-storage">
      </a>
      16.3 Transactional Storage of Dictionary Data
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  <p>
   The data dictionary schema stores dictionary data in transactional
      (
   <code class="literal">
    InnoDB
   </code>
   ) tables. Data dictionary tables are
      located in the
   <code class="filename">
    mysql
   </code>
   database together with
      non-data dictionary system tables.
  </p>
  <p>
   Data dictionary tables are created in a single
   <code class="literal">
    InnoDB
   </code>
   tablespace named
   <code class="filename">
    mysql.ibd
   </code>
   , which resides in the MySQL data
      directory. The
   <code class="filename">
    mysql.ibd
   </code>
   tablespace file must
      reside in the MySQL data directory and its name cannot be modified
      or used by another tablespace.
  </p>
  <p>
   Dictionary data is protected by the same commit, rollback, and
      crash-recovery capabilities that protect user data that is stored
      in
   <code class="literal">
    InnoDB
   </code>
   tables.
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