I am using Solr to power faceting features for our e-commerce application. Its been implemented in standard way as described here https://wiki.apache.org/solr/SimpleFacetParameters#Tagging_and_excluding_Filters
On application side, we have used facets returned by Solr to offer filtering experience on UI and the URLs are built using the facets as params. These parameters are then used to further pass on the faceting parameters for fq into Solr.
This works great except that our URLs are case sensitive as the moment we change to small case the facet query no longer work and gives us Undefined field error.
How can we have Case insensitive Solr Query for Faceting but still preserve case for results that are being used to display facets?