title: Do you use EnsureIndex() only once, or for evey document you insert into the database?
body: <p>I'm learning how to use LiteDB. Here's a bit of C# code I use to insert a .Net object into the database:</p>
  
  <pre><code>     // Create new YacksProjectInfo object and insert it into the database
       YacksProjectInfo projectInfo = new YacksProjectInfo(AssemblyName, moduleNumber);
       yacksProjects.Insert(projectInfo);  // Id field generated automatically
       yacksProjects.EnsureIndex((YacksProjectInfo x) =&gt; x.ProjectName);
       yacksProjects.EnsureIndex((YacksProjectInfo x) =&gt; x.ModuleNumber);
  </code></pre>
  
  <p>In other words, I'm using the EnsureIndex() method every time I add a new object to the database. But I'm guessing this isn't necessary, that you only need to do it once after inserting the first object.</p>
  
  <p>Can someone confirm if EnsureIndex() needs to be done every time, or if once is enough?</p>