title: Collect all Gerrit reviews
body: <p>For my current research, I want to gather all closed reviews from <a href="https://www.gerritcodereview.com" rel="nofollow noreferrer">Gerrit</a> instance, e.g from <a href="https://gerrit.googlesource.com/gerrit" rel="nofollow noreferrer">Gerrit itself</a>.</p>
  
  <p>My first attempt was to go via the REST API. However, there is a <a href="https://gerrit-review.googlesource.com/Documentation/access-control.html#capability_queryLimit" rel="nofollow noreferrer">limit for queries</a>, set by the Gerrit administrator. So I cannot collect all reviews and it is quite slow for large instances. </p>
  
  <p>There would be a tool, namely <a href="https://github.com/chaoss/grimoirelab-perceval" rel="nofollow noreferrer">Perceval</a>, but this requires SSH access, which I do not have, obviously.</p>
  
  <p>So I think I need to go over git. As far as I understood, all reviews/changes under review are stored in <code>refs/changes/...</code>. </p>
  
  <p>So I  </p>
  
  <pre><code>git ls-remote https://gerrit.googlesource.com/gerrit | grep /changes/ | awk '{print $2;}' 
  </code></pre>
  
  <p>which lists all heads:</p>
  
  <pre><code>...
  refs/changes/99/99999/3
  refs/changes/99/99999/4
  refs/changes/99/99999/5
  refs/changes/99/99999/meta
  ...
  </code></pre>
  
  <p>Then I can iterate through this list. 
  But</p>
  
  <pre><code>git fetch https://gerrit.googlesource.com/gerrit refs/changes/99/99999/meta
  </code></pre>
  
  <p>does not work. </p>
  
  <p>I also tried to mirror the git repository with</p>
  
  <pre><code>git clone --mirror https://gerrit.googlesource.com/gerrit
  </code></pre>
  
  <p>but this does not include the <code>changes</code> folder.</p>
  
  <p>Am I on the wrong track? What can I do instead? Of course, completely new ideas are also welcome!</p>