GCP Professional Data Engineer Practice Question

AlloyDB for PostgreSQL is a fully managed, PostgreSQL-compatible service that separates compute and log-structured storage to deliver high write throughput and near-linear read scaling through read pools. It offers an integrated columnar engine that accelerates analytical queries by orders of magnitude on the same operational data, and Google handles replication, patching, and zero-downtime maintenance. Cloud SQL provides PostgreSQL compatibility but lacks the columnar accelerator and can suffer from replication lag under heavy write loads. Spanner's PostgreSQL interface is not identical to upstream PostgreSQL and would require more re-engineering, while BigQuery excels at analytics but is not suitable for high-write OLTP workloads and would force a dual-system architecture.