title: Confirmation before removing all unused index in the datastore (GAE / Java)
body: <p>I have a website in production, and I would like to avoid doing a big mistake...
  I would like to use vaccum index command </p>
  
  <blockquote>
    <p>./appengine-java-sdk/bin/appcfg.sh vacuum_indexes myapp/war</p>
  </blockquote>
  
  <p>Does a backup can help restoring all indexes ?<br>
  Have you any recomendation before doing this kind of operation ?<br>
  Here is my datastore-indexes.xml: </p>
  
  <pre><code>&lt;datastore-index kind="Event"   ancestor="false" source="manual"&gt;
  &lt;property name="date_list"      direction="asc" /&gt;
  &lt;property name="e_name"         direction="asc" /&gt;  
  &lt;/datastore-index&gt;
  &lt;datastore-index kind="U"       ancestor="false" source="manual"&gt;
  &lt;property name="u02_name"       direction="asc" /&gt;
  &lt;property name="u04_zona"       direction="asc" /&gt;
  &lt;/datastore-index&gt;
  &lt;datastore-index kind="S"       ancestor="false" source="manual"&gt;
  &lt;property name="cookie"         direction="asc" /&gt;
  &lt;property name="dateCreated"    direction="asc" /&gt;
  &lt;/datastore-index&gt;
  </code></pre>
  
  <p>Here is a screeshot of my current indexes status (in red, are the indexes I should actually use):
  <img src="https://i.stack.imgur.com/ZWWlL.jpg" alt="enter image description here">
  Thanks you,</p>