.setFetchSource(false).setSize(fessConfig.getPageScoreBoosterMaxFetchSizeAsInteger()).execute().actionGet(requestTimeout);
        return Arrays.stream(response.getHits().getHits()).map(SearchHit::getId).toArray(n -> new String[n]);
    };

    protected Function<Map<String, Object>, Long> requestHandler = params -> {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();

        int count = 0;
        String scrollId = response.getScrollId();
        try {
            while (scrollId != null) {
                final SearchHits searchHits = response.getHits();
                final SearchHit[] hits = searchHits.getHits();
                if (hits.length == 0) {
                    break;
                }

                final BulkRequestBuilder bulkRequest = client.prepareBulk();

                .setQuery(queryBuilder).setSize(0).setTrackTotalHits(true).execute().actionGet(fessConfig.getIndexSearchTimeout());
        final TotalHits totalHits = countResponse.getHits().getTotalHits();
        if (totalHits != null) {
            return totalHits.value;
        }
        return 0;
    }

    public long deleteBySessionId(final String sessionId) {