final SearchEngineClient searchEngineClient = ComponentUtil.getSearchEngineClient();
                final String index = fessConfig.getIndexDocumentUpdateIndex();
                searchEngineClient.admin().indices().prepareRefresh(index).execute().actionGet();
                final long numOfDeleted = searchEngineClient.deleteByQuery(index, queryBuilder);
                logger.info("[{}] Deleted {} stale documents.", dataConfig.getName(), numOfDeleted);

    //                                                                              ======
    public RefreshResponse refresh() {
        return client.admin().indices().prepareRefresh(asEsIndex()).execute().actionGet(refreshTimeout);
    }

    // ===================================================================================

    //                                                                              ======
    public RefreshResponse refresh() {
        return client.admin().indices().prepareRefresh(asEsIndex()).execute().actionGet(refreshTimeout);
    }

    // ===================================================================================

    //                                                                              ======
    public RefreshResponse refresh() {
        return client.admin().indices().prepareRefresh(asEsIndex()).execute().actionGet(refreshTimeout);
    }

    // ===================================================================================

     * @return the refresh status code
     */
    protected int refreshIndex(final SearchEngineClient searchEngineClient, final String index) {
        final RefreshResponse response = searchEngineClient.admin().indices().prepareRefresh(index).execute().actionGet();
        if (logger.isDebugEnabled()) {
            logger.debug("[{}] refresh status: {} ({}/{}/{})", index, response.getStatus(), response.getTotalShards(),

     */
    public long getDocumentCount(final String indexName) {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        try {
            client.admin().indices().prepareRefresh(indexName).execute().actionGet(fessConfig.getIndexIndicesTimeout());
            try (CurlResponse response = ComponentUtil.getCurlHelper().get("/" + indexName + "/_count").execute()) {