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    <div>
     <h4 class="title">
      <a name="collation-diagnostics">
      </a>
      12.14.4.3 Diagnostics During Index.xml Parsing
     </h4>
    </div>
   </div>
  </div>
  <p>
   The MySQL server generates diagnostics when it finds problems
          while parsing the
   <code class="filename">
    Index.xml
   </code>
   file:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      Unknown tags are written to the error log. For example,
              the following message results if a collation definition
              contains a
      <code class="literal">
       &lt;aaa&gt;
      </code>
      tag:
     </p>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-none"><div class="docs-select-all right" id="sa72810425"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[Warning] Buffered warning: Unknown LDML tag:
'charsets/charset/collation/rules/aaa'</code></pre>
     </div>
    </li>
    <li class="listitem">
     <p>
      If collation initialization is not possible, the server
              reports an
      <span class="quote">
       “
       <span class="quote">
        Unknown collation
       </span>
       ”
      </span>
      error, and
              also generates warnings explaining the problems, such as
              in the previous example. In other cases, when a collation
              description is generally correct but contains some unknown
              tags, the collation is initialized and is available for
              use. The unknown parts are ignored, but a warning is
              generated in the error log.
     </p>
    </li>
    <li class="listitem">
     <p>
      Problems with collations generate warnings that clients
              can display with
      <a class="link" href="show-warnings.html" title="15.7.7.42 SHOW WARNINGS Statement">
       <code class="literal">
        SHOW
              WARNINGS
       </code>
      </a>
      . Suppose that a reset rule contains an
              expansion longer than the maximum supported length of 6
              characters:
     </p>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-xml"><div class="docs-select-all right" id="sa33482238"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-xml"><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>reset</span><span class="token punctuation">&gt;</span></span>abcdefghi<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>reset</span><span class="token punctuation">&gt;</span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>i</span><span class="token punctuation">&gt;</span></span>x<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>i</span><span class="token punctuation">&gt;</span></span></code></pre>
     </div>
     <p>
      An attempt to use the collation produces warnings:
     </p>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa63166861"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SELECT</span> _utf8mb4<span class="token string">'test'</span> <span class="token keyword">COLLATE</span> utf8mb4_test_ci<span class="token punctuation">;</span>
<span class="token output">ERROR 1273 (HY000)<span class="token punctuation">:</span> Unknown collation<span class="token punctuation">:</span> 'utf8mb4_test_ci'</span>
<span class="token prompt">mysql&gt;</span> <span class="token keyword">SHOW</span> <span class="token keyword">WARNINGS</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Level   <span class="token punctuation">|</span> Code <span class="token punctuation">|</span> Message                                <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Error   <span class="token punctuation">|</span> 1273 <span class="token punctuation">|</span> Unknown collation: 'utf8mb4_test_ci'   <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Warning <span class="token punctuation">|</span> 1273 <span class="token punctuation">|</span> Expansion is too long at 'abcdefghi=x' <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
     </div>
    </li>
   </ul>
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