Files not properly deleted from swish_fulltext

I found that there were files in swish_fulltext table that either whose paths had been changed or whose nodes had been deleted. My thought was to always delete all swish_fulltext records associated with a node anytime the node is submitted or deleted. Deleting by the filepath doesn't catch files whose filepaths have changed.

/**
* Implementation of hook_nodeapi(). Updates Full Text Information on Node Update.
*/
function swish_nodeapi(&$node, $op) {
  switch($op) {
    case "insert":
    case "update":
    case "submit":
    // Check if this node has any references in the files table
    // Note: we do this because other attachments might not be found in $node->file
    $result = db_query("SELECT filepath FROM {files} WHERE nid = %d", $node->nid);
    if (db_num_rows($result) && $node->nid) {
      // If there's a result in files, then delete everything in swish_fulltext for this node and re-populate.
      db_query("DELETE FROM {swish_fulltext} WHERE nid = %d", $node->nid);
      while ($row = db_fetch_object($result)) {
        $text = _swish_do_text_extract($row->filepath);
        // Do a delete and reinsert, in case anything has gone wrong before and the row isn't there already
        db_query("DELETE FROM {swish_fulltext} WHERE filepath = '%s'", $row->filepath);
        db_query("INSERT INTO {swish_fulltext} (filepath, nid, `fulltext`) VALUES ('%s',%d,'%s')", $row->filepath, $node->nid, $text);
      }
    }
    break;
    case "update index":
      // return text to be placed in the search index
    break;
    case "search result":
      // return items to be added to search results
    break;
    case "delete":
    // Check if this node has any references in the files table
    // Note: we do this because other attachments might not be found in $node->file
    $result = db_query("SELECT filepath FROM {files} WHERE nid = %d", $node->nid);
    if (db_num_rows($result) && $node->nid) {
      // If there's a result, then delete everything in swish_fulltext for this node.
      db_query("DELETE FROM {swish_fulltext} WHERE nid = %d", $node->nid);
    }
    break;
   }
}

Perhaps I'm way off base on this, but this seems to more accurately help make sure we don't have files in swish_fulltext that shouldn't be there.