final SearchRequestBuilder builder = client.prepareSearch(index);
        builder.setSize(size);
        builder.setQuery(buildQuery());
        builder.setRescorer(buildRescore(), windowSize);

        builder.execute(new ActionListener<SearchResponse>() {
            @Override

        if (skipDuplicateWords) {
            builder.setSize(size * 2);
        } else {
            builder.setSize(size);
        }

        // set query.
        final QueryBuilder q = buildQuery(query, fields);

        // set function score
        final QueryBuilder queryBuilder = buildFunctionScoreQuery(query, q);
        builder.addSort("_score", SortOrder.DESC);

        // set filter query.