Hi, SOLR-7036 introduced a new faster method for group.facet, which uses UnInvertedField. It was patched for version 4.x. Over the last week, my colleague uploaded a new patch that work against the trunk.
We would really appreciate if anyone could take a look at it and give us some feedback about it. Full details and performance tests results were also added to the JIRA issue. We are willing to work at it and if possible backport it to an older branch. Link: https://issues.apache.org/jira/browse/SOLR-7036 Thanks in advance,