You can use the database layer to achieve read-write separation as well. Martin Fowler mentioned reporting databases. With Azure Sql Database which is a SAAS yo

You can use the database layer to achieve read-write separation as well. Martin Fowler mentioned reporting databases. With Azure Sql Database which is a SAAS you can pay for readable replicas. I have never used Google Spanner. But my understanding of Google Spanner database is it was designed from scratch so that reads never will slow down writes so it scales out of the box.