Why is my on-demand Amazon DynamoDB table being throttled?

Last updated: 2022-08-16

My on-demand Amazon DynamoDB table is being throttled.

Short description

Your DynamoDB on-demand table might be throttled due to one of the following common reasons:

  • The traffic is more than double the previous peak.
  • The traffic exceeds the per-partition maximum.
  • The traffic exceeds the per-table account quota.
  • The global secondary index of your table is being throttled.

Resolution

Amazon DynamoDB on-demand is a flexible option that can serve thousands of requests per second without capacity planning. DynamoDB on-demand offers pay-per-request pricing for read and write requests so that you pay only for what you use. DynamoDB tables using on-demand capacity mode automatically adapt to your application’s traffic volume. However, tables using the on-demand mode might still throttle.

The traffic is more than double the previous peak

You might experience throttling if you exceed double your previous traffic peak within 30 minutes. It's a best practice to spread your traffic growth over at least 30 minutes before exceeding double your previous traffic peak. Use the ConsumedReadCapacityUnits metric in Amazon CloudWatch to monitor traffic to the table. For more information, see DynamoDB metrics and dimensions.

For new on-demand tables, you can immediately drive up to 4,000 write request units or 12,000 read request units, or any linear combination of the two. For an existing table that you switched to on-demand capacity mode, the previous peak is half the previous provisioned throughput for the table, or the settings for a newly created table with on-demand capacity mode, whichever is higher. For more information, see Initial throughput for on-demand capacity mode.

The traffic exceeds the per-partition maximum

Each partition on the table can serve up to 3,000 read request units or 1,000 write request units, or a linear combination of both. If the traffic to a partition exceeds this limit, then the partition might be throttled. To resolve this issue:

  1. Use CloudWatch Contributor Insights for DynamoDB to identify the most frequently accessed and throttled keys in your table.
  2. Randomize the requests to the table so that the requests to the hot partition keys are distributed over time. For more information, see Using write sharding to distribute workloads evenly.

The traffic exceeds the per-table account quota

For on-demand tables, the table-level read throughput and table-level write throughput quotas apply at the account level. By default, the table throughput is set to a maximum of 40,000 read requests units and a maximum of 40,000 write requests units. If the traffic to a table exceeds the per-table account quotas for throughput, then the table might be throttled. To resolve this issue, use the Service Quotas console to increase the table-level read throughput and write throughput quotas for your account.

The global secondary index of your table is being throttled

If your DynamoDB table has a secondary global index that's being throttled, the throttling might create back pressure throttles on the base table. For more information, see How does throttling on my global secondary index affect my Amazon DynamoDB table? and Using global secondary indexes in DynamoDB.