title: Optimizing MySQL query with nested select statements?
body: <p>I've got <em>read-only</em> access to a MySQL database, and I need to loop through the following query about 9000 times, each time with a different $content_path_id.  I'm calling this from within a PERL script that's pulling the '$content_path_id's from a file.</p>
  
  <pre><code>SELECT an.uuid FROM alf_node an WHERE an.id IN 
      (SELECT anp.node_id FROM alf_node_properties anp WHERE anp.long_value IN 
          (SELECT acd.id FROM alf_content_data acd WHERE acd.content_url_id = $content_path_id));
  </code></pre>
  
  <p>Written this way, it's taking <em>forever</em> to do each query (approximately 1 minute each).  I'd really rather not wait 9000+ minutes for this to complete if I don't have to.  Is there some way to speed up this query?  Maybe via a join? My current SQL skills are embarrassingly rusty...</p>