title: Apply Solr filter query to only part of the search results
body: <p>I have a Solr solution working which requires two queries, but I'm looking for a way to do it in a single query.  My idea is that if I can figure out a way to do this, I wont have to incur the overhead of twice the load on the Solr cluster.  </p>
  
  <p>The details: I'm running a simple query like "q=camera" with a query filter of say "fq=type:digital". The second query is identical to the first, but the filter is the inverse, like "fq=-type:digital"  I'm imagining that if there's a way to run a single query while applying the first filter to get the first set of topDocs, then generate a second set with the second filter the results could be merged and returned ( it doesn't matter if sorting resorts and mixes the two sets).  </p>
  
  <p>I experimented with partitioning the data by marking a specific field during indexing, into two different groups and then using Solr "grouping" queries, but the response time for these wasn't acceptable in my setup. </p>
  
  <p>I'm looking for suggestions the most Solr congruent approach to experiment with: tuning to improve the two-query solution performance, or investigating a kind of custom Solr post-filter ( I read Yonik's 2/2012 blog post ).</p>
  
  <p>I have to implement this in Solr 3.5, although if there's a slam dunk solution in 4.0 I'll eventually be able to move to that.</p>