Yes, you're right Yoann: we write too many documents to the index. This can be measured / assert by the JSR-352 standard MetricType.WRITE_COUNT in the test. You can see my implementation (v3) if there's anything helpful https://github.com/yrodiere/hibernate-search/compare/jsr352...mincong-h:HSEARCH-2758-fix-index-progress-v3