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<title>平滑重建索引</title>
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<a href="http://www.xunsearch.com" target="_blank">Xunsearch PHP-SDK</a> v1.3.2 权威指南
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	<h1 id="-">平滑重建索引</h1>

<p>前一章讲到有些情况不得不需要重建索引，可以用 <a href="../api/XSIndex.html#clean">XSIndex::clean</a> 立即全部清空所有数据，
然后再把现有数据全部添加到索引数据库中。</p>

<p>但这种方式的缺点对于线上项目是难以容忍的，因此可以选择使用平滑重建方式。它的内部实现
相当于在一个临时区域开辟新库，把所有的添加操作全部更新到新库，直到您完成重建，完成后
再用新库替代旧库用于搜索。</p>

<p>在编代码时，把所有的 <a href="../api/XSIndex:add.html">XSIndex:add</a> 操作都放进 <a href="../api/XSIndex.html#beginRebuild">XSIndex::beginRebuild</a> 和 
<a href="../api/XSIndex.html#endRebuild">XSIndex::endRebuild</a> 之间即可。写法参考如下：</p>

<div class="hl-code"><div class="php-hl-main"><pre><span class="php-hl-comment">//</span><span class="php-hl-comment"> 宣布开始重建索引</span>
<span class="php-hl-var">$index</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">beginRebuild</span><span class="php-hl-brackets">(</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;
 
</span><span class="php-hl-comment">//</span><span class="php-hl-comment"> 然后在此开始添加数据</span><span class="php-hl-code">
...
</span><span class="php-hl-var">$index</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">add</span><span class="php-hl-brackets">(</span><span class="php-hl-var">$doc</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;
...
 
</span><span class="php-hl-comment">//</span><span class="php-hl-comment"> 告诉服务器重建完比</span>
<span class="php-hl-var">$index</span><span class="php-hl-code">-&gt;</span><span class="php-hl-identifier">endRebuild</span><span class="php-hl-brackets">(</span><span class="php-hl-brackets">)</span><span class="php-hl-code">;</span></pre></div></div>

<blockquote class="note">
<p><strong>Note:</strong> 为确保重建的顺利完成，请在重建时不要对同一个项目开启多个进程、
  连接同时交替重建以免发生错乱。</p>
</blockquote>

<div class="revision">$Id$</div>
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		<div class="prev"><a href="index.clean.html">&laquo; 清空索引</a></div>
			<div class="next"><a href="index.buffer.html">使用索引缓冲区 &raquo;</a></div>
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