Having read this chapter, you should now be familiar with the concept of relational databases on the cloud, transactions, and ACID-support. You will have some clarity around how Cloud SQL can be used to set up MySQL or PostgreSQL databases on the GCP and some of the considerations in choosing between Cloud SQL and Cloud Spanner. You will also be familiar with the intricacies of replicas and backups on Cloud SQL. Finally, we have also discussed how Cloud Spanner represents a cutting-edge, Google-proprietary RDBMS that can scale horizontally to support pretty much any dataset size and level of QPS (queries-per-second).