Exam Professional Cloud Database Engineer topic 1 question 113 discussion

D - spanner ABC it is about Cloud SQL and the options don't offer anything to improve writing latency

Another metric to note is that the latency for regional persistent disk with solid-state drives (SSD) is higher than it would be for a zonal persistent disk with SSD. https://cloud.google.com/sql/docs/mysql/high-availability#ha-performance

To minimize write latency in a single-region web application, Option C (zonal Cloud SQL without HA) is the optimal choice. By avoiding synchronous replication across zones, it ensures write operations are committed with minimal overhead. While this configuration lacks automatic failover, it aligns with the priority of reducing latency for write-heavy workloads. Alternatives like HA Cloud SQL or Cloud Spanner introduce multi-zone synchronization, which inherently increases latency.

I vote for C. There is zero mention of HA or 4x9s (if so, then for sure Spanner - D). More critically, CloudSQL-Postgres would have measurably and consistently lower write latency than Spanner on single row writes (which would be this use case).

multiples zonas has more latency

The only one with write latency is regional Spanner

Correct answer is D - Use Cloud Spanner in a regional configuration.

its Cloud SQL vs Spanner . Spanner has advantage in writing latency

A, B, C. replicas and HA will help in improving read latency only. Cloud SQL enables customers to implement horizontal scaling of read-only workloads using read replicas. It might degrade the write latency. D. Spanner satisfies the requirement without sacrificing availability

I think D.

Spanner has higher write latency than other options

D: just choose Cloud Spanner over Cloud SQL

A and B add latency. C screams of an anti-pattern to me (no HA). Spanner satisfies the requirement without sacrificing availability, so D.