(PECL solr >= 0.9.2)
Sorts the fields within the document
public bool SolrInputDocument::sort ( int $sortOrderBy [, int $sortDirection = SolrInputDocument::SORT_ASC ] )
The fields are rearranged according to the specified criteria and sort direction
Fields can be sorted by boost values, field names and number of values.
The $order_by parameter must be one of :
* SolrInputDocument::SORT_FIELD_NAME