title: Solr Re-index behavior
body: <p>I am new to Solr and I am trying to understand its behavior during a re-index. 
  I have a batch process running that selects data from a relational table and adds it to a Solr index.</p>
  
  <p>From what I understand reading about Solr, there are two cases when you need to do a re-index</p>
  
  <p>Case 1: When new rows gets inserted into your table (source data)
   Case 2: When any of column type changes and you have to change the schema accordingly.</p>
  
  <p>Does the old data remain available in Case 1 for users to search against while the re-index is happening? </p>
  
  <p>What happens during a schema change as the old data will no longer match the new schema ? What kind of behavior will users experience when they perform a search ?</p>
  
  <p>I could not find any clear answers to these questions online. Any clarification is appreciated.</p>