How to do facet group query on Apache solr
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I am doing a facet query on solr.. Which gives me facets and its count for each item... But now I want to perform a group query on facets.. Which gives me count according to group...

Example
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Below is the data

Item1: Nike shoes (size:8,9,10)
Item2 : Reebok Shoes(size:8,9,10)

Now in this case my brand facet query returns me result as below  

 - Nike:3 
  
 - Reebok:3


The result I required is  

 - Nike:1 
 - Reebok:1

Regards