title: How to track down a Drupal max_allowed_packet error?
body: <p>One of my staging sites has recently started spewing <strong>huge</strong> errors on every admin page along the lines of:</p>
  
  <p><code>User warning: Got a packet bigger than &#039;max_allowed_packet&#039; bytes query: UPDATE cache_update SET data = &#039;</code> ... <code>&#039;, created = 1298434692, expire = 1298438292, serialized = 1 WHERE cid = &#039;update_project_data&#039; in _db_query() (line 141 of /var/www/vhosts/mysite/mypath/includes/database.mysqli.inc).</code> <strong>(where "..." is about 1.5 million characters worth of serialized data)</strong></p>
  
  <p>How should I go about tracking down where the error originates? Would adding debugging code to _db_query do any good, since it gets called so much?</p>