Hi, Pulsar community Currently, we retain all null-key messages during topic compaction, which I don't think is necessary because when you use topic compaction, it means that you want to retain the value according to the key, so retaining null-key messages is meaningless.
Additionally, retaining all null-key messages will double the storage cost, and we'll never be able to clean them up since the compacted topic has not supported the retention policy yet. In summary, I don't think we should retain null-key messages during topic compaction. Looking forward to your feedback! Thanks, Cong Zhao
