Hello
Our application (VuFind, a library discovery tool) is speaking to a solr 3.5 index per
default. To get the facet values back, the param 'facet.sort' is sent in the request with
an empty value. Solr then delivers the called facets sorted by count, as it should be. A
request looks (simplified) like this:
http://[host:port]/solr/[core]/select/?q=*:*&rows=10&fl=*,score&start=0&facet=true&facet.mincount=1&facet.limit=30&facet.sort=&facet.field=authorStr&wt=xml
We switched from solr 3.5 to solr 4.1 and discovered that the request built by our
application yields an undesired result, facets are sorted by index. This is the behaviour:
* facet.sort= //with the empty value, facets are sorted by index
* facet.sort=count|index //obviously, facets are sorted as told
* no facet.sort parameter //facets are sorted by count, as the default should be
A quick test on a solr 4.0 instance shows that the behaviour is still backward compatible
with 3.5. An empty value delivers standard sorting by count, a non-existing parameter as well.
Short: 4.1 is not backwards compatible to 3.5 and to 4.0 with regard to facet
sorting.
We suspect this has to do with the change from boolean to string in the
setFacetSort Method:
http://lucene.apache.org/solr/api-4_0_0-BETA/org/apache/solr/client/solrj/SolrQuery.html#setFacetSort%28java.lang.String%29
Questions are:
* Is this known? I guess so
* Is there a way to fix this on the solr side?
* What are the reasons behind the change?
If not, we obviously should to this in the client app.
Regards
Oliver
