(PECL solr >= 0.9.2)
SolrQuery::getTermsSort — Returns an integer indicating how terms are sorted
SolrQuery::TERMS_SORT_INDEX indicates that the terms are returned by index order. SolrQuery::TERMS_SORT_COUNT implies that the terms are sorted by term frequency (highest count first)
此函数没有参数。
Returns an integer on success and NULL if not set.