Waiting for PostgreSQL 19 – Implement ALTER TABLE … MERGE

PostgreSQL 19 introduces ALTER TABLE commands for merging and splitting partitions. The new MERGE PARTITIONS command combines multiple partitions into one, while SPLIT PARTITION divides a single partition into several. Both operations currently hold ACCESS EXCLUSIVE locks during execution, making them unsuitable for large tables under high load, but they provide a foundation for future optimizations with reduced locking and potential parallelism. These features were previously attempted in PostgreSQL 17 but were rolled back due to issues.