We need to make sure DSQ instances don't end up in the query cache.
It's important that the DrillSidewaysScorer (bulk scorer implementation) actually runs during query evaluation in order to populate the "sideways" FacetsCollector instances with "near miss" docs. If it gets cached, this won't happen.
There may also be an implication around acceptDocs getting honored as well. zacharymorn may be able to provide more details.
UPDATE: The original issue I detailed above isn't actually an issue since DrillDownQuery doesn't implement equals, so the cache always misses and it always executes the BulkScorer ( DrillSidewaysScorer ). Tricky! There is a separate issue found by Zach (as mentioned above) related to "acceptDocs" though. See below conversation and link off to the separate PR conversation for more details.