[Marco van Herwaarden]

It is done in the mark_thread_read() function of ./includes/functions_bigthree.php.

I would however advice against changing it, as it is not using a sutdown query on purpose:

PHP Code:

  // can't be shutdown as we do a read query below on this table
  $db->query_write("
   REPLACE INTO " . TABLE_PREFIX . "threadread
    (threadid, userid, readtime)
   VALUES
    ($threadinfo[threadid], $userid, $time)
  ");