Flink 2.1 introduces DeltaJoin and MultiJoin, revolutionary join operators designed to tackle the excessive state management challenges in streaming applications. By externalizing state retrieval and leveraging Apache Fluss's efficient prefix lookup capabilities, these innovations aim to improve checkpoint efficiency and scalability, addressing the long-standing issues of traditional streaming joins. The article also contrasts Flink's approach with alternatives like RisingWave and Feldera, highlighting different philosophies in handling streaming state and joins.