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     <h2 class="title">
      <a name="data-dictionary-limitations">
      </a>
      16.8 Data Dictionary Limitations
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  <a class="indexterm" name="idm46045167499952">
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  <p>
   This section describes temporary limitations introduced with the
      MySQL data dictionary.
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    <li class="listitem">
     <p>
      Manual creation of database directories under the data
          directory (for example, with
      <span class="command">
       <strong>
        mkdir
       </strong>
      </span>
      ) is
          unsupported. Manually created database directories are not
          recognized by the MySQL Server.
     </p>
    </li>
    <li class="listitem">
     <p>
      DDL operations take longer due to writing to storage, undo
          logs, and redo logs instead of
      <code class="filename">
       .frm
      </code>
      files.
     </p>
    </li>
   </ul>
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