private static String _getSearchEngineId(Document document) {
    String entryClassName = document.get("entryClassName");

    Indexer indexer = IndexerRegistryUtil.getIndexer(entryClassName);

    String searchEngineId = indexer.getSearchEngineId();

    if (_log.isDebugEnabled()) {
      _log.debug("Search engine ID for " + indexer.getClass() + " is " + searchEngineId);
    }

    return searchEngineId;
  }