title: Solr drops/deletes all old documents while reindexing
body: <p>Version: <strong>Solr 4.1</strong></p>
  
  <p>Problem statement: </p>
  
  <ol>
  <li><p>Solr delete/drops all the old documents when we click on the full-import od Data import handler. After the full import is complete, every thing works fine.</p></li>
  <li><p>help me understand the JVM values attached as image, I am trying to connect it to the issue.</p></li>
  </ol>
  
  <p>As per my understanding solr will not delete/drop the old documents till the new documents are imported fully. But in my case it drops the old documents while new documents are partially imported.</p>
  
  <p>Details:</p>
  
  <ol>
  <li>We are using Solr Cloud with single shard and 2 replica.
  S1-R1--------S1-R2</li>
  <li>Using a amazon load balancer to balance the hit on each of them.</li>
  <li>Both of the solr are attached to 3 zookepers.</li>
  <li><p>Memory allocation: JAVA_OPTS="$JAVA_OPTS -Xms8192m -Xmx12288m -XX:PermSize=3072m -XX:MaxPermSize=8192m -Xss4m"</p></li>
  <li><p>The solr admin panel is showing:</p>
  
  <ul>
  <li>Physical Memory 98.2%</li>
  <li>Swap Space 0.0%</li>
  <li>File Descriptor Count 0.2%</li>
  <li>JVM-Memory 34.3%</li>
  </ul></li>
  </ol>
  
  <p><a href="https://i.stack.imgur.com/pZEN5.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pZEN5.jpg" alt="Solr Admin Panel JVM info"></a></p>