# Change data capture with Amazon DynamoDB
Many applications benefit from capturing changes to items stored in a DynamoDB table, at the point in time when such changes occur. The following are some example use cases:
+ A popular mobile app modifies data in a DynamoDB table, at the rate of thousands of updates per second. Another application captures and stores data about these updates, providing near-real-time usage metrics for the mobile app.
+ A financial application modifies stock market data in a DynamoDB table. Different applications running in parallel track these changes in real time, compute value-at-risk, and automatically rebalance portfolios based on stock price movements.
+ Sensors in transportation vehicles and industrial equipment send data to a DynamoDB table. Different applications monitor performance and send messaging alerts when a problem is detected, predict any potential defects by applying machine learning algorithms, and compress and archive data to Amazon Simple Storage Service (Amazon S3).
+ An application automatically sends notifications to the mobile devices of all friends in a group as soon as one friend uploads a new picture.
+ A new customer adds data to a DynamoDB table. This event invokes another application that sends a welcome email to the new customer.
DynamoDB supports streaming of item-level change data capture records in near-real time. You can build applications that consume these streams and take action based on the contents.
**Note**
Adding tags to DynamoDB Streams and using [attribute-based access control (ABAC)](access-control-resource-based.md) with DynamoDB Streams aren't supported.
The following video will give you an introductory look at the change data capture concept.
[](http://www.youtube.com/watch?v=VVv_-mZ5Ge8)
**Topics**
+ [Streaming options for change data capture](#streamsmain.choose)
+ [Using Kinesis Data Streams to capture changes to DynamoDB](kds.md)
+ [Change data capture for DynamoDB Streams](Streams.md)
## Streaming options for change data capture
DynamoDB offers two streaming models for change data capture: Kinesis Data Streams for DynamoDB and DynamoDB Streams.
To help you choose the right solution for your application, the following table summarizes the features of each streaming model.
| Properties | Kinesis Data Streams for DynamoDB | DynamoDB Streams |
| --- | --- | --- |
| Data retention | Up to [1 year](https://docs.aws.amazon.com/streams/latest/dev/kinesis-extended-retention.html). | 24 hours. |
| Kinesis Client Library (KCL) support | Supports [KCL versions 1.X, 2.X, and 3.X](https://docs.aws.amazon.com/streams/latest/dev/custom-kcl-consumers.html). | Supports [KCL versions 1.X and 2.X](https://docs.aws.amazon.com/streams/latest/dev/custom-kcl-consumers.html). |
| Number of consumers | Up to [5 simultaneous](https://docs.aws.amazon.com/streams/latest/dev/service-sizes-and-limits.html) consumers per shard, or up to 20 simultaneous consumers per shard with [enhanced fan-out](https://docs.aws.amazon.com/streams/latest/dev/enhanced-consumers.html). | Up to [2 simultaneous](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Limits.html#limits-dynamodb-streams) consumers per shard. |
| Throughput quotas | Unlimited. | Subject to throughput [quotas](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Limits.html#limits-dynamodb-streams) by DynamoDB table and AWS Region. |
| Record delivery model | Pull model over HTTP using [GetRecords](https://docs.aws.amazon.com/kinesis/latest/APIReference/API_GetRecords.html) and with [enhanced fan-out](https://docs.aws.amazon.com/streams/latest/dev/enhanced-consumers.html), Kinesis Data Streams pushes the records over HTTP/2 by using [SubscribeToShard](https://docs.aws.amazon.com/kinesis/latest/APIReference/API_SubscribeToShard.html). | Pull model over HTTP using [GetRecords](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_streams_GetRecords.html). |
| Ordering of records | The timestamp attribute on each stream record can be used to identify the actual order in which changes occurred in the DynamoDB table. | For each item that is modified in a DynamoDB table, the stream records appear in the same sequence as the actual modifications to the item. |
| Duplicate records | Duplicate records might occasionally appear in the stream. | No duplicate records appear in the stream. |
| Stream processing options | Process stream records using [AWS Lambda](https://docs.aws.amazon.com/lambda/latest/dg/with-kinesis.html), [Amazon Managed Service for Apache Flink](https://docs.aws.amazon.com/kinesisanalytics/latest/dev/what-is.html), [Kinesis data firehose](https://docs.aws.amazon.com/firehose/latest/dev/what-is-this-service.html) , or [AWS Glue streaming ETL](https://docs.aws.amazon.com/glue/latest/dg/add-job-streaming.html). | Process stream records using [AWS Lambda](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Streams.Lambda.html) or [DynamoDB Streams Kinesis adapter](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Streams.KCLAdapter.html). |
| Durability level | [ Availability zones](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/disaster-recovery-resiliency.html) to provide automatic failover without interruption. | [ Availability zones](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/disaster-recovery-resiliency.html) to provide automatic failover without interruption. |
You can enable both streaming models on the same DynamoDB table.
The following video talks more about the differences between the two options.
[](http://www.youtube.com/watch?v=UgG17Wh2y0g)