title: Postgres postgis failed to re-find parent key in index for deletion target page
body: <p>I have problem with GiST index and autovacuum. My pg_log contains many errors</p>
  
  <blockquote>
    <p>ERROR:  failed to re-find parent key in index for "%TABLE" deletion target page</p>
    
    <blockquote>
      <p>CONTEXT:  automatic vacuum of table</p>
    </blockquote>
  </blockquote>
  
  <p>Why it may happens?</p>
  
  <p>Postgres - 9.1.14</p>