Toke Eskildsen has been working with Lucene and Solr for 8 years, most of that time as technical lead on all things search at the State and University Library, Denmark. During that time he has developed a full hierarchical faceting system for Lucene (LUCENE-2369 / SOLR-2412) and written a patch for improving faceting performance for high cardinality fields in Solr (SOLR-5894). He is somewhat fixated on bit fiddling and search performance.