Why is there a replication delay on my DynamoDB global table?

Last updated: 2020-07-08

How can I reduce replication latency for Amazon DynamoDB global tables?

Resolution

Note: There are two versions of DynamoDB global tables: version 2019.11.21 and version 2017.11.29. To find out which version you're using, see Determining the  version of global tables you are using. It's a best practice to use version 2019.11.21. This version is more efficient and consumes less write capacity than version 2017.11.29. To upgrade, see Updating global tables to version 2019.11.21 (current).

Here are some common causes of high replication latency:

  • DynamoDB publishes the ReplicationLatency and PendingReplicationCount metrics to Amazon CloudWatch for each replica in the global table. If either of these metrics is elevated for an extended period, check if write requests are throttled in the global table Regions. To assure that you have enough provisioned capacity to perform replicated writes to all global table Regions, use DynamoDB Auto Scaling or on-demand capacity mode. For more information, see Best practices and requirements for managing global tables.
  • ReplicationLatency might vary for different source and destination pairs, depending on how geographically far apart the tables are from each other. For example, ReplicationLatency is typically lower for global tables in the Europe (Ireland) and Europe (London) Regions than for tables in the Europe (Ireland) and Asia Pacific (Sydney) Regions.
  • ReplicationLatency and PendingReplicationCount might increase when an AWS Region becomes degraded. Use the AWS Service Health Dashboard to check for events in the Regions where you have replica tables. If there's an event, then you can temporarily redirect your application's read and write activity to a different Region.
  • When you upgrade from version 2017.11.21 to version 2019.11.29, you might see an increase in ReplicationLatency. This is expected. For more information, see Updating global tables to version 2019.11.21 (current).

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