*/
    public SuggestDeleteResponse deleteDocumentWords() {
        if (logger.isInfoEnabled()) {
            logger.info("Deleting document words: index={}", index);
        }
        return deleteWordsByKind(FieldNames.DOC_FREQ, SuggestItem.Kind.DOCUMENT, item -> item.setDocFreq(0), SuggestItem.Kind.QUERY,
                SuggestItem.Kind.USER);
    }

    /**
     * Deletes query words.