Flink 1.20 Adds Significant Improvements Along w/Deprecations

What this post added

This post details the technical advancements in Apache Flink 1.20, including the introduction of the `DISTRIBUTED BY` clause for unified bucketing strategies in Flink SQL (FLIP-376), the `MATERIALIZED` table concept for managing data freshness and automating refresh jobs (FLIP-435), and parallel aggregations on non-keyed streams for the DataStream API (FLIP-380). It also covers operational improvements like unified file merging for checkpoints (FLIP-306), RocksDB SST file compaction (FLINK-26050), and batch job recovery from JobMaster failures (FLIP-383). The post highlights API deprecations in preparation for Flink 2.0.