DynamoDB Streams can now start reading at a timestamp with the AT_TIMESTAMP shard iterator
Victoria Shinder2 min readAWS announced on 15 October 2026 that Amazon DynamoDB Streams supports timestamp-based stream processing. A consumer can now pick a point in time and receive records from there on, using the AT_TIMESTAMP shard iterator type.
What changes. Until now, AWS says, a consumer could start only from the oldest retained record, which is at most 24 hours old, or from records written after it began consuming the stream. The announcement names four uses for the new starting point: recovering after an interruption without reprocessing the whole retained stream or missing records; replaying data from a specific point for debugging and auditing; skipping a backlog by resuming near the newest records; and synchronising after a restore by starting at the export timestamp that follows a point-in-time recovery (PITR) export.
How it is configured. The feature is used with the Kinesis Client Library (KCL) through the DynamoDB Streams Kinesis Adapter, version 2.5.0 or later, according to the developer guide. It needs the same IAM permissions as an existing adapter application and no additional API permissions. In code, the application creates an InitialPositionInStreamExtended with newInitialPositionAtTimestamp(...), passes it to StreamsSchedulerFactory.createSingleStreamTracker and registers the returned tracker with the ConfigsBuilder. The adapter then initialises each new lease with AT_TIMESTAMP, calls GetShardIterator with the timestamp and hands the iterator to GetRecords, which returns records from the first one whose ApproximateCreationDateTime is at or after that time.
Edge cases the guide spells out. A timestamp older than the retained records does not raise an error: the application starts at the oldest record still available in each shard, and records past the 24-hour retention window cannot be recovered. A timestamp in the future is rejected by the adapter during initialisation, without any API call, and processing does not start; the guide advises allowing for clock differences between the host and the service when choosing a time close to now.
Do not switch a running application. The guide warns against changing the timestamp, or switching between AT_TIMESTAMP, TRIM_HORIZON and LATEST, in an application whose state is stored in a lease table: shards with checkpoints continue from them, and shards that have not started either use the new setting or fail, so different shards can end up at different starting points. Its recommended fix is to stop every worker, delete the lease table, update the configuration and restart; the alternative is a new application name, which makes KCL create a new lease table and leaves the old one for rollback.
Availability and price. The feature is available in all commercial AWS Regions, the AWS GovCloud (US) Regions and the China Regions, with no charge beyond the standard GetRecords request charges.
Source: AWS What's New, 15 October 2026 — https://aws.amazon.com/about-aws/whats-new/2026/10/amazon-dynamodb-streams-timestamp-processing/ ; developer guide: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Streams.Timestamp.html