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     <h4 class="title">
      <a name="key-cache-block-size">
      </a>
      10.10.2.5 Key Cache Block Size
     </h4>
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  <p>
   It is possible to specify the size of the block buffers for an
          individual key cache using the
   <a class="link" href="server-system-variables.html#sysvar_key_cache_block_size">
    <code class="literal">
     key_cache_block_size
    </code>
   </a>
   variable. This permits tuning of the performance of I/O
          operations for index files.
  </p>
  <p>
   The best performance for I/O operations is achieved when the
          size of read buffers is equal to the size of the native
          operating system I/O buffers. But setting the size of key
          nodes equal to the size of the I/O buffer does not always
          ensure the best overall performance. When reading the big leaf
          nodes, the server pulls in a lot of unnecessary data,
          effectively preventing reading other leaf nodes.
  </p>
  <p>
   To control the size of blocks in the
   <code class="filename">
    .MYI
   </code>
   index file of
   <code class="literal">
    MyISAM
   </code>
   tables, use the
   <a class="link" href="server-options.html#option_mysqld_myisam-block-size">
    <code class="option">
     --myisam-block-size
    </code>
   </a>
   option at
          server startup.
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