What is Timestream scaling behavior with On-Demand pricing (without maxQueryTCU set)?

In Amazon Timestream when the "On-demand" compute mode is used with the maxQueryTCU value not explicitly set, the service uses a default configuration to allocate compute resources for queries. Here's how it works:

• Default Setting: By default, each AWS account has a maxQueryTCU limit of 200 TCUs (Timestream Compute Units).
• On-Demand Allocation: Timestream dynamically allocates TCUs based on the complexity of your queries and the volume of data being processed.
• Scaling Behavior: The service will scale up to the default limit of 200 TCUs as needed to serve your queries efficiently

The TCU pricing model can potentially improve query scalability and reduce throttling. With TCU-based pricing, you have more control over the maximum compute resources allocated to your queries. This can help prevent unexpected throttling due to exceeding query capacity. By setting an appropriate maxQueryTCU value, you can ensure that your queries have access to the necessary compute resources while also maintaining cost control.

TCU-based pricing does not cause outages or query failures during the transition. The transition itself doesn't inherently cause increased query latency. In fact, by properly configuring your maxQueryTCU, you may be able to improve query performance and reduce the likelihood of throttling.

When considering the switch to TCU-based pricing, it's recommended to monitor your current query performance and usage patterns. You can use CloudWatch metrics like QueryTCU to understand your compute unit consumption and set an appropriate maxQueryTCU value. This will help ensure a smooth transition and optimal query performance under the TCU pricing model.

Remember that with TCU-based pricing, you're only billed for the TCUs your queries actually consume. Setting a higher maxQueryTCU limit doesn't impact your costs unless those TCUs are used by your workload. This gives you the flexibility to accommodate peak usage periods without incurring unnecessary costs during periods of lower demand.

Sources
Timestream Compute Unit (TCU) - Amazon Timestream
Understanding and optimizing Amazon Timestream Compute Units for efficient time series data management | AWS Database Blog
Queries - Amazon Timestream Amazon Timestream pricing