both of the mentioned features from Citus and Timescale are extensions on PostgreSQL, so they do not alter the way storage works in PostgreSQL in any meaningful

both of the mentioned features from Citus and Timescale are extensions on PostgreSQL, so they do not alter the way storage works in PostgreSQL in any meaningful manner. AlloyDB Seems better compared to Aurora, and they seem to share a significant amount of design principles with log-shipping, but now with an extra caching layer at or near the database instance. As for the 'columnar' features, from the release post it seems like AlloyDB does not specifically store the data at rest in a columnar format, but transforms the rows into columnar for analytical queries (but I'm not sure about that). That indeed improves performance of certain classes of queries.