(PECL solr >= 0.9.2)
Sorts the fields in the document
public bool SolrDocument::sort ( int $sortOrderBy [, int $sortDirection = SolrDocument::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 sortOrderBy parameter must be one of :
* SolrDocument::SORT_FIELD_NAME
* SolrDocument::S