Google Cloud recently announced the launch of Committed Use Discounts (CUDs) for Cloud Spanner. The option triggers a 20% to 40% discount on the on-demand price of the managed relational database in exchange for a commitment of one or three years.
Discounts apply to the compute capacity, measured in nodes or processing units, across instance configurations and regions, and are designed for workloads with predictable needs. Shambhu Hegde, product manager at Google Cloud, explains how they apply:
Once you make a commitment to spend a certain amount on an hourly basis on Spanner from a billing account, you can get discounts on instances in different instance configurations, regions, and projects associated with that billing account. Both regional and multi-region instances can utilize the same spend commitment. (...) If for business reasons you need to migrate your application from single region to multi-region in future, you can do so with the same commitment while continuing to enjoy the discounts.
Source: https://cloud.google.com/blog/products/databases/spanner-committed-use-discounts-help-reduce-costs
The CUDs are available in all regions and do not apply to storage, backup, and network egress costs. Hegde adds an example of use case that would benefit from CUDs:
Let's say you have a couple of Spanner instances in different regions and you have provisioned a total of 125 nodes. Let’s say you are consistently spending an average of $100/hour on this computer capacity. Let's further assert that you feel confident this usage rate will not decline over the next year. This sort of steady usage represents an excellent opportunity to buy a Spanner committed use discount—in this case, a one-year commitment to spend $100/hour on Spanner nodes, in exchange for a 20% discount to that commitment.
Introduced five years ago, Cloud Spanner is a globally distributed, scalable database service on Google Cloud that provides horizontal scaling and RDBMS features without sharding or clustering. The introduction of PostgreSQL interface and of the Spanner dialect for SQLAlchemy are Cloud Spanner improvements recently covered by InfoQ.
Committed use discounts are available on different services on Google Cloud: resource-based discounts are offered for Compute Engine, while spend-based discounts exist for Cloud Spanner, Cloud SQL, VMware Engine, Cloud Run, and Google Kubernetes Engine in autopilot mode.
Google is not the only cloud provider that allows committing capacity on a database to obtain price reductions. Azure offers reserved capacity for Azure Cosmos DB. Amazon has DynamoDB reservations and reserved instances for Aurora, MySQL, MariaDB, PostgreSQL, Oracle and SQL Server database engines, but they both lack the regional flexibility of the CUDs on Cloud Spanner.
One-year commitments on Cloud Spanner provide a 20% discount, three-year commitments provide a 40% discount. The commitment fee for the compute capacity is billed monthly.