Hi all, I am working a lot with Drupal and Apache Solr. There, we implemented a performance improvement that would, for filter-only queries (i.e., no "q" parameter, just "fq"s) instead move the filters to the "q.alt" parameter (idea based on this blog post [1]).
[1] https://web.archive.org/web/20120817044656/http://www.derivante.com/2009/04/27/100x-increase-in-solr-performance-and-throughput Before, we had "q.alt=*:*" to return all results and then filter via "fq". So, e.g., this query: q.alt=*:*&fq=field1:foo&fq=field2:bar becomes this: q.alt=(field1:foo) AND (field2:bar) However, now I've read some complaints that the former is actually faster, and some other people also pointed out (in separate discussions) that "fq" is much faster than "q". So, can anyone shed some lights on this, what the internal mechanics are that make the one or the other faster? Are there other suggestions for how to make a "filters-only" search as fast as possible? Also, can it be that it recently changed that the "q.alt" parameter now influences relevance (in Solr 5.x)? I could have sworn that wasn't the case previously. Thanks in advance, Thomas
