sort by relevance does nothing apachesolr drupal facet

In my dupal solr facet, when i do sort by title its working and it append ?solrsort=sort_title asc in url but sort by relevance does nothing with the results and does not append any parameter 开发者_StackOverflowin the url Can any one guide me about this Thanks in advance

By default without any sort parameters, Solr sort the results by score.
So you need not append any sort parameters when you intend to sort by relevance.