DynamoDB Streams and AWS Lambda Triggers
Amazon DynamoDB is integrated with AWS Lambda so that you can create triggers—pieces of code that automatically respond to events in DynamoDB Streams. With triggers, you can build applications that react to data modifications in DynamoDB tables.
If you enable DynamoDB Streams on a table, you can associate the stream ARN with a Lambda function that you write. Immediately after an item in the table is modified, a new record appears in the table's stream. AWS Lambda polls the stream and invokes your Lambda function synchronously when it detects new stream records.
The Lambda function can perform any actions you specify, such as sending a notification
or
initiating a workflow. For example, you can write a Lambda function to simply copy
each
stream record to persistent storage, such as Amazon Simple Storage Service (Amazon
S3), to create a permanent audit
trail of write activity in your table. Or suppose you have a mobile gaming app that
writes
to a GameScores table. Whenever the TopScore attribute of the
GameScores table is updated, a corresponding stream record is written to
the table's stream. This event could then trigger a Lambda function that posts a
congratulatory message on a social media network. (The function would simply ignore
any
stream records that are not updates to GameScores or that do not modify the
TopScore attribute.)
For more information about AWS Lambda, see the AWS Lambda Developer Guide.
