Because score desc is the default Lucene Solr behavior when no explicit
sort is specified, QueryParsing.parseSort() returns a null sort so that the
non-sort versions of the query execution routines get called. However the
caller SolrPluginUtils.parseSort issues that warning whenever it gets a
A little background:
I originally conceived of query operation chains (based on some of my
previous hacking in mechanical investing stock screens: select all
stocks; take top 10% lowest PE; then take the top 20 highest growth
rate; then sort descending by 13 week relative strength).
So, I
