Using streams for capturing and reacting to changes in the data - ( DynamoDB Streams )

Syntax

import boto3
from boto3.dynamodb.conditions import Key, Attr

# Create a DynamoDB client
dynamodb = boto3.client('dynamodb')

# Configure the stream
stream_arn = 'arn:aws:dynamodb:us-west-2:123456789012:table/ExampleTable/stream/2017-06-21T20:20:34.794'

# Open the stream
stream = dynamodbstreams.connect_to_region('us-west-2')
dyn_stream = stream.describe_stream(stream_arn)

# Get the shard iterator
shard_id = dyn_stream['StreamDescription']['Shards'][0]['ShardId']
shard_it = stream.get_shard_iterator(stream_arn, shard_id, 'LATEST')["ShardIterator"]

# Read the stream
while True:
    out = stream.get_records(shard_it, limit=2)
    shard_it = out["NextShardIterator"]
    records = out["Records"]
    for record in records:
        print(record["dynamodb"])

Example

import boto3
from boto3.dynamodb.conditions import Key, Attr

# Create a DynamoDB client
dynamodb = boto3.client('dynamodb')

# Configure the stream
stream_arn = 'arn:aws:dynamodb:us-west-2:123456789012:table/ExampleTable/stream/2017-06-21T20:20:34.794'

# Open the stream
stream = dynamodbstreams.connect_to_region('us-west-2')
dyn_stream = stream.describe_stream(stream_arn)

# Get the shard iterator
shard_id = dyn_stream['StreamDescription']['Shards'][0]['ShardId']
shard_it = stream.get_shard_iterator(stream_arn, shard_id, 'LATEST')["ShardIterator"]

# Read the stream
while True:
    out = stream.get_records(shard_it, limit=2)
    shard_it = out["NextShardIterator"]
    records = out["Records"]
    for record in records:
        print(record["dynamodb"])

Output

{u'SequenceNumber': u'12', u'Keys': {u'ItemId': {u'S': u'1'}}, u'NewImage': {u'Price': {u'N': u'20'}, u'ItemId': {u'S': u'1'}, u'Title': {u'S': u'Example Item 1'}}, u'SizeBytes': 70, u'ApproximateCreationDateTime': 1498106418.06, u'StreamViewType': u'NEW_AND_OLD_IMAGES'}
{u'SequenceNumber': u'13', u'Keys': {u'ItemId': {u'S': u'2'}}, u'NewImage': {u'Price': {u'N': u'25'}, u'ItemId': {u'S': u'2'}, u'Title': {u'S': u'Example Item 2'}}, u'SizeBytes': 73, u'ApproximateCreationDateTime': 1498106420.677, u'StreamViewType': u'NEW_AND_OLD_IMAGES'}

Explanation

Amazon DynamoDB Streams is a feature of DynamoDB that allows you to capture changes to items in your table. With DynamoDB Streams, you can build applications that consume these changes and react to them in real time.

To use DynamoDB Streams, you need to configure a stream on your table. Once the stream is configured, you can open it and read the data from it using the boto3 DynamoDBStreams client.

In the example code above, we create a DynamoDB client and configure a stream for our table. We then open the stream and get a shard iterator, which we can use to read data from the stream.

We then enter a loop that reads records from the stream and prints them out. In this example, we are printing out the entire "dynamodb" record, which contains information about the change that was made to the item.

Use

DynamoDB Streams can be used to build a variety of applications that require real-time access to item changes in a DynamoDB table. For example, you could use DynamoDB Streams to:

• Build a real-time dashboard that displays changes to items in your table
• Trigger notifications or alerts based on changes to items in your table
• Replicate data from your DynamoDB table to another data store in real time

The possibilities are endless, and the only limit is your imagination.

Important Points

• DynamoDB Streams is a feature of DynamoDB that allows you to capture changes to items in your table.
• To use DynamoDB Streams, you need to configure a stream on your table.
• Once your stream is configured, you can open it and read data from it using the boto3 DynamoDBStreams client.
• DynamoDB Streams can be used to build real-time applications that react to changes in a DynamoDB table.
• With DynamoDB Streams, you can build a variety of applications, including real-time dashboards, alerts and notifications, and data replication.

Summary

DynamoDB Streams is a powerful feature of DynamoDB that allows you to capture changes to items in your table and build real-time applications that react to those changes. With the boto3 DynamoDBStreams client, you can easily read data from your stream and build applications that consume and react to the data in real time.