AMAZON RDS FOR POSTGRESQL 17.4

Summary from the TLDR Web Dev newsletter

Jepsen tested Amazon RDS for PostgreSQL multi-AZ clusters and found that they violate Snapshot Isolation, the strongest consistency model supported across all endpoints. The clusters had G-nonadjacent cycles and anomalies across various versions (13.15 to 17.4), suggesting that they had weaker consistency models like Parallel Snapshot Isolation. This behavior is less safe than a single-node PostgreSQL system.