I thought about it for quite some time, whether I should write about it, and how. That's why there is delay since:
On 6th of April 2024, Alexander Korotkov committed patch:
Implement ALTER TABLE ... MERGE PARTITIONS ... command This new DDL command merges several partitions into the one partition of the target table. The target partition is created using new createPartitionTable() function with parent partition as the template. This commit comprises quite naive implementation which works in single process and holds the ACCESS EXCLUSIVE LOCK on the parent table during all the operations including the tuple routing. This is why this new DDL command can't be recommended for large partitioned tables under a high load. However, this implementation come in handy in certain cases even as is. Also, it could be used as a foundation for future implementations with lesser locking and possibly parallel. Discussion: https://postgr.es/m/c73a1746-0cd0-6bdd-6b23-3ae0b7c0c582%40postgrespro.ru Author: Dmitry Koval Reviewed-by: Matthias van de Meent, Laurenz Albe, Zhihong Yu, Justin Pryzby Reviewed-by: Alvaro Herrera, Robert Haas, Stephane Tachoires
and, also on 6th of April 2024, Alexander Korotkov committed patch:
Implement ALTER TABLE ... SPLIT PARTITION ... command This new DDL command splits a single partition into several parititions. Just like ALTER TABLE ... MERGE PARTITIONS ... command, new patitions are created using createPartitionTable() function with parent partition as the template. This commit comprises quite naive implementation which works in single process and holds the ACCESS EXCLUSIVE LOCK on the parent table during all the operations including the tuple routing. This is why this new DDL command can't be recommended for large partitioned tables under a high load. However, this implementation come in handy in certain cases even as is. Also, it could be used as a foundation for future implementations with lesser locking and possibly parallel. Discussion: https://postgr.es/m/c73a1746-0cd0-6bdd-6b23-3ae0b7c0c582%40postgrespro.ru Author: Dmitry Koval Reviewed-by: Matthias van de Meent, Laurenz Albe, Zhihong Yu, Justin Pryzby Reviewed-by: Alvaro Herrera, Robert Haas, Stephane Tachoires
Continue reading Waiting for PostgreSQL 17 – MERGE / SPLIT partitions