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DynamoDB Streams

  • Ordered stream of item-level notifications (create/update/delete) in a table
  • Stream records can be:
    • Sent to Kinesis Data Streams
    • Read by AWS Lambda
    • Read by Kinesis Client Library Applications
  • Data Retention for up to 24 hours
  • Use cases:
    • react to changes in real-time (welcome email to users)
    • analytics
    • insert into derivative tables
    • insert into elasticsearch
    • implement cross-region replication

  • Ability to choose the information that will be written to the stream:
    • KEYS_ONLY - only the key attributes of the modified item
    • NEW_IMAGE - the entire item, as it appears after it was modified
    • OLD_IMAGE - the entire item, as it appeared before it was modified
    • NEW_AND_OLD_IMAGES - both the new and the old images of the item
  • DynamoDB Streams are made of shards, just like Kinesis Data Streams

  • You don't provision shards, this is automated by AWS

  • Records are not retroactively populated in a stream after enabling it.

DynamoDB Streams & AWS Lambda

  • You need to define an Event Source Mapping to read from a DynamoDB Streams
  • You need to ensure the Lambda function has the appropriate permissions
  • You Lambda function is invoked syncronously