<div id="docs-body">
 <div class="section">
  <div class="titlepage">
   <div>
    <div>
     <h2 class="title">
      <a name="data-dictionary-file-removal">
      </a>
      16.2 Removal of File-based Metadata Storage
     </h2>
    </div>
   </div>
  </div>
  <a class="indexterm" name="idm46045167771040">
  </a>
  <p>
   In previous MySQL releases, dictionary data was partially stored
      in metadata files. Issues with file-based metadata storage
      included expensive file scans, susceptibility to file
      system-related bugs, complex code for handling of replication and
      crash recovery failure states, and a lack of extensibility that
      made it difficult to add metadata for new features and relational
      objects.
  </p>
  <p>
   The metadata files listed below are removed from MySQL. Unless
      otherwise noted, data previously stored in metadata files is now
      stored in data dictionary tables.
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      <code class="filename">
       .frm
      </code>
      files: Table metadata files. With
          the removal of
      <code class="filename">
       .frm
      </code>
      files:
     </p>
     <div class="itemizedlist">
      <ul class="itemizedlist" style="list-style-type: circle; ">
       <li class="listitem">
        <p>
         The 64KB table definition size limit imposed by the
         <code class="filename">
          .frm
         </code>
         file structure is removed.
        </p>
       </li>
       <li class="listitem">
        <p>
         The Information Schema
         <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table">
          <code class="literal">
           TABLES
          </code>
         </a>
         table's
         <code class="literal">
          VERSION
         </code>
         column reports a
              hardcoded value of
         <code class="literal">
          10
         </code>
         , which is the
              last
         <code class="filename">
          .frm
         </code>
         file version used in MySQL
              5.7.
        </p>
       </li>
      </ul>
     </div>
    </li>
    <li class="listitem">
     <p>
      <code class="filename">
       .par
      </code>
      files: Partition definition files.
      <code class="literal">
       InnoDB
      </code>
      stopped using partition definition
          files in MySQL 5.7 with the introduction of native
          partitioning support for
      <code class="literal">
       InnoDB
      </code>
      tables.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="filename">
       .TRN
      </code>
      files: Trigger namespace files.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="filename">
       .TRG
      </code>
      files: Trigger parameter files.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="filename">
       .isl
      </code>
      files:
      <code class="literal">
       InnoDB
      </code>
      Symbolic Link files containing the location of
      <a class="link" href="glossary.html#glos_file_per_table" title="file-per-table">
       file-per-table
      </a>
      tablespace files created outside of the data directory.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="filename">
       db.opt
      </code>
      files: Database configuration
          files. These files, one per database directory, contained
          database default character set attributes.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="filename">
       ddl_log.log
      </code>
      file: The file contained
          records of metadata operations generated by data definition
          statements such as
      <a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement">
       <code class="literal">
        DROP TABLE
       </code>
      </a>
      and
      <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
       <code class="literal">
        ALTER TABLE
       </code>
      </a>
      .
     </p>
    </li>
   </ul>
  </div>
 </div>
 <br/>
</div>
