Committed use discounts (CUDs) for Cloud Spanner provide deeply discounted prices in exchange for your commitment to continuously use a certain amount of Cloud Spanner compute resources for a year or longer.
Cloud Spanner CUDs are ideal when your spending on Cloud Spanner compute capacity involves a predictable minimum that you can commit to for at least a year.
Cloud Spanner CUD pricing
Cloud Spanner CUDs offer two levels of discounts, depending on the commitment period:
A one-year CUD gives you a 20 percent discount from the on-demand rate.
A three-year CUD gives you a 40 percent discount from the on-demand rate.
When you purchase a CUD, you choose a one- or three-year period, as well as a commitment amount: your expected Cloud Spanner expenditure on compute capacity per hour over that period. This commitment amount, after the application of your discount, becomes your commitment fee. You are then billed for this commitment fee on a monthly basis for the duration of the CUD's period. (For a full example, see An example Cloud Spanner CUD, below.)
The discount applies to any eligible usage in Cloud Spanner projects associated with the Cloud Billing account used to purchase the CUD, regardless of instance configuration or region. All CUDs apply to both regional and multi-region configurations.
Any expenditure beyond the commitment gets billed at the on-demand rate. As your Cloud Spanner usage grows, you can purchase additional CUDs to receive discounts on increased expenditures not covered by previous commitments.
If Cloud Spanner's on-demand rates change after you purchase a CUD, your commitment fee does not change, and you still receive the same discount percentage on applicable usage.
Resources eligible for Cloud Spanner CUDs
Cloud Spanner committed use discounts automatically apply to your spending on Cloud Spanner compute capacity (as measured in nodes or processing units) across projects. This flexibility helps you achieve a high utilization rate of your commitment across regions and projects without manual intervention, saving you time and money.
Cloud Spanner CUDs do not apply to your spending on Cloud Spanner storage, backup, or network egress.
Purchase a Cloud Spanner CUD
To purchase or manage Cloud Spanner committed use discounts for your Cloud Billing account, you must have a Billing Account Administrator role with that account.
You can purchase a Cloud Spanner CUD in the Google Cloud console billing page. Select the Commitments tab, then select the PURCHASE action at the top. Read the Purchasing spend-based commitments section in Google Cloud's documentation for more details.
After purchasing a CUD, the commitment goes into effect within the next hour. Its discounts are automatically applied to subsequent eligible usage.
Please note that, after your purchase a CUD, you cannot cancel its commitment. Make sure the size and duration of your commitment aligns with both your historical and your expected minimum expenditure on Cloud Spanner compute capacity.
In addition, before you purchase a commitment, please read the Service Specific Terms regarding Committed Units.
An example Cloud Spanner CUD scenario
Your commitment should represent your expected minimum hourly expenditure on Cloud Spanner compute capacity across your projects over the next one or three years.
As an example, say that you use Cloud Spanner instances in two
us-west2. You provision a
compute capacity of 10 nodes for an instance in
us-central1, and 20
nodes for an instance in
From the pricing page, you can calculate the approximate hourly commitment cost:
- Expenditure in
us-central1: 10 nodes * $0.90 per node per hour = $9.00 per hour
- Expenditure in
us-west2: 20 nodes * $1.08 per node per hour = $21.60 per hour
- Total expenditure across all regions: $9.00 + $21.60 = $30.60 per hour
If you expect to spend that minimum of $30.60 per hour continuously for
the next year or more, then you can make a commitment for that amount.
In other words, when purchasing that CUD, you would enter "
the hourly on-demand commitment amount.
If, on the other hand, you expect to scale down the compute capacity occasionally, you can make a commitment for a lower amount. Any expenditure above that limit is charged at the on-demand rate.
Continuing this example, assume that you do decide on a commitment of $30.60 per hour. As your next step, you choose the length of the commitment's period.
As a basis for comparison, compute the on-demand cost of Spanner compute capacity at the chosen commitment rate, without the application of any commitment discounts:
- Monthly cost based on on-demand pricing: $30.60 per hour * 730 hours = $22,338 per month
From here, you can calculate the monthly costs and savings you would see under a 1-year CUD, applying its 20% discount, compared to a year of paying the full on-demand rates:
- Monthly cost of a 1-year, $30.60/hour commitment: ($30.60 per hour - 20% discount) * 730 hours = $17,870.40 per month
- Total savings per month: $22,338 - $17,870.40 = $4,467.60
- Total savings with a 1-year, $30.60/hour commitment: $4,467.6 per month * 12 months = $53,611.20
You can apply similar math to calculating the costs and savings of a 3-year CUD, with its 40% discount compared to on-demand rates:
- Monthly cost of a 3-year, $30.60/hour commitment: ($30.60 per hour - 40% discount) * 730 hours = $13,402.80 per month
- Total savings per month: $22,338 - $13,402.80 = $8,935.20
- Total savings with a 3-year, $30.60/hour CUD: $8,935.20 per month * 36 months = $321,667.20
As you can see, a commitment that covers your expected minimum Cloud Spanner usage over the years to come can lead to significant savings. Read on for our recommendations on choosing the right CUD size for your Cloud Spanner projects.
Recommendations for choosing a commitment
While considering the purchase of Cloud Spanner CUDs, keep in mind the following:
Regions: Cloud Spanner CUDs apply across instance configurations or regions. They apply to both regional and multi-region configurations. If you have Cloud Spanner instances in multiple regions, calculate the expenditure across all the regions your projects use while making a commitment.
Projects: Determine the consistent baseline expenditure per project while calculating total commitment. Consider that production loads usually run 100% of the time, while development or staging environments may often run intermittently.
Instances: If you provision Cloud Spanner instances to use a steady level of compute capacity around the clock, consider buying CUDs fully covering their compute resource consumption. However, if you instead frequently scale your instances up or down, consider purchasing CUDs only for their baseline predictable usage.
If you have instances that you run only for bursts or brief durations, exclude them from your calculations.
Your commitment fee applies to every hour during the term of the commitment, regardless of actual usage. Choose your CUD's commitment amount carefully, based on both your historical Cloud Spanner usage and your future expectations. As long as your use of Cloud Spanner compute capacity stays above your committed expenditure level, you will enjoy the maximum possible discount for the length of that commitment.
Learn how to view your CUD reports.
Understand savings with cost breakdown reports.
See the list of Cloud Spanner SKUs that Cloud Spanner CUDs apply to.