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Estimate RU/s using the Azure Cosmos DB capacity planner - API for NoSQL

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APPLIES TO: NoSQL

Note

If you are planning a data migration to Azure Cosmos DB and all that you know is the number of vcores and servers in your existing sharded and replicated database cluster, please also read about estimating request units using vCores or vCPUs

Configuring your Azure Cosmos DB databases and containers with the right amount of provisioned throughput, or Request Units (RU/s), for your workload is essential to optimizing cost and performance. This article describes how to use the Azure Cosmos DB capacity planner to get an estimate of the required RU/s and cost of your workload when using the API for NoSQL. If you are using API for MongoDB, see how to use capacity calculator with MongoDB article.

Capacity planner modes

Mode Description
Basic Provides a quick, high-level RU/s and cost estimate. This mode assumes the default Azure Cosmos DB settings for indexing policy, consistency, and other parameters.

Use basic mode for a quick, high-level estimate when you are evaluating a potential workload to run on Azure Cosmos DB. To learn more, see how to estimate cost with basic mode.
Advanced Provides a more detailed RU/s and cost estimate, with the ability to tune more settings—indexing policy, consistency level, and other parameters that affect the cost and throughput.

Use advanced mode when you are estimating RU/s for a new project or want a more detailed estimate. To learn more, see how to estimate cost with advanced mode.

Estimate provisioned throughput and cost using basic mode

To get a quick estimate for your workload using the basic mode, navigate to the capacity planner. Enter in the following parameters based on your workload:

Input Description
API Choose API for NoSQL
Number of regions Azure Cosmos DB is available in all Azure regions. Select the number of regions required for your workload. You can associate any number of regions with your Azure Cosmos DB account. See global distribution in Azure Cosmos DB for more details.
Multi-region writes If you enable multi-region writes, your application can read and write to any Azure region. If you disable multi-region writes, your application can write data to a single region.

Enable multi-region writes if you expect to have an active-active workload that requires low latency writes in different regions. For example, an IOT workload that writes data to the database at high volumes in different regions.

Multi-region writes guarantees 99.999% read and write availability. Multi-region writes require more throughput when compared to the single write regions. To learn more, see how RUs are different for single and multiple-write regions article.
Total data stored in transactional store Total estimated data stored(GB) in the transactional store in a single region.
Use analytical store Choose On if you want to use analytical store. Enter the Total data stored in analytical store, it represents the estimated data stored (GB) in the analytical store in a single region.
Item size The estimated size of the data item (for example, document), ranging from 1 KB to 2 MB.
Queries/sec Number of queries expected per second per region. The average RU charge to run a query is estimated at 10 RUs.
Point reads/sec Number of point read operations expected per second per region. Point reads are the key/value lookup on a single item ID and a partition key. To learn more about point reads, see the options to read data article.
Creates/sec Number of create operations expected per second per region.
Updates/sec Number of update operations expected per second per region. When you choose automatic indexing, the estimated RU/s for the update operation is calculated as one property being changed per an update.
Deletes/sec Number of delete operations expected per second per region.

After filling the required details, select Calculate. The Cost Estimate tab shows the total cost for storage and provisioned throughput. You can expand the Show Details link in this tab to get the breakdown of the throughput required for different CRUD and query requests. Each time you change the value of any field, select Calculate to recalculate the estimated cost.

Capacity planner basic mode

Estimate provisioned throughput and cost using advanced mode

Advanced mode allows you to provide more settings that impact the RU/s estimate. To use this option, navigate to the capacity planner and sign in to the tool with an account you use for Azure. The sign-in option is available at the right-hand corner.

After you sign in, you can see more fields compared to the fields in basic mode. Enter the other parameters based on your workload.

Input Description
API Azure Cosmos DB is a multi-model and multi-API service. Choose API for NoSQL.
Number of regions Azure Cosmos DB is available in all Azure regions. Select the number of regions required for your workload. You can associate any number of regions with your Azure Cosmos DB account. See global distribution in Azure Cosmos DB for more details.
Multi-region writes If you enable multi-region writes, your application can read and write to any Azure region. If you disable multi-region writes, your application can write data to a single region.

Enable multi-region writes if you expect to have an active-active workload that requires low latency writes in different regions. For example, an IOT workload that writes data to the database at high volumes in different regions.

Multi-region writes guarantees 99.999% read and write availability. Multi-region writes require more throughput when compared to the single write regions. To learn more, see how RUs are different for single and multiple-write regions article.
Default consistency Azure Cosmos DB supports 5 consistency levels, to allow developers to balance the tradeoff between consistency, availability, and latency tradeoffs. To learn more, see the consistency levels article.

By default, Azure Cosmos DB uses session consistency, which guarantees the ability to read your own writes in a session.

Choosing strong or bounded staleness will require double the required RU/s for reads, when compared to session, consistent prefix, and eventual consistency. Strong consistency with multi-region writes is not supported and will automatically default to single-region writes with strong consistency.
Indexing policy By default, Azure Cosmos DB indexes all properties in all items for flexible and efficient queries (maps to the Automatic indexing policy).

If you choose off, none of the properties are indexed. This results in the lowest RU charge for writes. Select off policy if you expect to only do point reads (key value lookups) and/or writes, and no queries.

If you choose Automatic, Azure Cosmos DB automatically indexes all the items as they are written.

Custom indexing policy allows you to include or exclude specific properties from the index for lower write throughput and storage. To learn more, see indexing policy and sample indexing policies articles.
Total data stored in transactional store Total estimated data stored(GB) in the transactional store in a single region.
Use analytical store Choose On if you want to use analytical store. Enter the Total data stored in analytical store, it represents the estimated data stored(GB) in the analytical store in a single region.
Workload mode Select Steady option if your workload volume is constant.

Select Variable option if your workload volume changes over time. For example, during a specific day or a month. The following setting is available if you choose the variable workload option:
  • Percentage of time at peak: Percentage of time in a month where your workload requires peak (highest) throughput.


For example, if you have a workload that has high activity during 9am – 6pm weekday business hours, then the percentage of time at peak is: (9 hours per weekday at peak * 5 days per week at peak) / (24 hours per day at peak * 7 days in a week) = 45 / 168 = ~27%.

With peak and off-peak intervals, you can optimize your cost by programmatically scaling your provisioned throughput up and down accordingly.
Item size The size of the data item (for example, document), ranging from 1 KB to 2 MB. You can add estimates for multiple sample items.

You can also Upload sample (JSON) document for a more accurate estimate.

If your workload has multiple types of items (with different JSON content) in the same container, you can upload multiple JSON documents and get the estimate. Use the Add new item button to add multiple sample JSON documents.
Number of properties The average number of properties per an item.
Point reads/sec Number of point read operations expected per second per region. Point reads are the key/value lookup on a single item ID and a partition key. Point read operations are different from query read operations. To learn more about point reads, see the options to read data article. If your workload mode is Variable, you can provide the expected number of point read operations at peak and off peak.
Creates/sec Number of create operations expected per second per region.
Updates/sec Number of update operations expected per second per region.
Deletes/sec Number of delete operations expected per second per region.
Queries/sec Number of queries expected per second per region. For an accurate estimate, either use the average cost of queries or enter the RU/s your queries use from query stats in Azure portal.
Average RU/s charge per query By default, the average cost of queries/sec per region is estimated at 10 RU/s. You can increase or decrease it based on the RU/s charges based on your estimated query charge.

You can also use the Save Estimate button to download a CSV file containing the current estimate.

Capacity planner advanced mode

The prices shown in the Azure Cosmos DB capacity planner are estimates based on the public pricing rates for throughput and storage. All prices are shown in US dollars. Refer to the Azure Cosmos DB pricing page to see all rates by region.

Next steps