When doing a search like
http://localhost:8983/solr/select?group=true&group.func=product(fildname1,fieldname2)&group.facet=true&facet=true&facet.field=fieldname3
an error is returned in response where facets are normally returned:
java.lang.ArrayIndexOutOfBoundsException: 0 at org.apache.solr.request.SimpleFacets.getGroupedCounts(SimpleFacets.java:358) ...
The function used can be any function, not product only. There is no such error if group.facet is omitted or group.field is used instead of group.func. It seems that group.field parameter is expected to be defined when calculating grouped facets.
The question: is there another way to use both query functions, or an appropriate work-around, or a tip on where in Solr source to look into this?
This question cross posted from a Solr Jira issue 3742. This issue relates to Solr 4 beta that launched very recently.
