Hello, As described in https://issues.apache.org/jira/browse/SOLR-13126 multiplicative boots (in certain conditions) seem to be broken since 7.3. The error seems to be introduced in https://issues.apache.org/jira/browse/LUCENE-8099. Reverting the SOLR parts to the now deprecated BoostingQuery again fixes the issue. The filed issue contains a test case and a patch with the revert (for testing purposes, not really a clean fix). We sadly couldn't find the actual issue, which seems to lie with the use of "FunctionScoreQuery" for boosting.
We were able to patch our 7.5 installation with the patch. As others might be affected as well, we hope this can be helpful in resolving this bug. To all SOLR/Lucene developers, thank you for your work. Looking trough the code base gave me a new appreciation of your work. Best Regards, Tobias PS: This issue was already posted by a colleague, "Inconsistent debugQuery score with multiplicative boost", but I wanted to create a new post with a clearer title.
