Complete scan of dynamoDb with boto3

Solution 1:

I think the Amazon DynamoDB documentation regarding table scanning answers your question.

In short, you'll need to check for LastEvaluatedKey in the response. Here is an example using your code:

import boto3
dynamodb = boto3.resource('dynamodb',
                          aws_session_token=aws_session_token,
                          aws_access_key_id=aws_access_key_id,
                          aws_secret_access_key=aws_secret_access_key,
                          region_name=region
)

table = dynamodb.Table('widgetsTableName')

response = table.scan()
data = response['Items']

while 'LastEvaluatedKey' in response:
    response = table.scan(ExclusiveStartKey=response['LastEvaluatedKey'])
    data.extend(response['Items'])

Solution 2:

boto3 offers paginators that handle all the pagination details for you. Here is the doc page for the scan paginator. Basically, you would use it like so:

import boto3

client = boto3.client('dynamodb')
paginator = client.get_paginator('scan')

for page in paginator.paginate():
    # do something

Solution 3:

Riffing off of Jordon Phillips's answer, here's how you'd pass a FilterExpression in with the pagination:

import boto3

client = boto3.client('dynamodb')
paginator = client.get_paginator('scan')
operation_parameters = {
  'TableName': 'foo',
  'FilterExpression': 'bar > :x AND bar < :y',
  'ExpressionAttributeValues': {
    ':x': {'S': '2017-01-31T01:35'},
    ':y': {'S': '2017-01-31T02:08'},
  }
}

page_iterator = paginator.paginate(**operation_parameters)
for page in page_iterator:
    # do something

Solution 4:

DynamoDB limits the scan method to 1mb of data per scan.

Documentation: https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/dynamodb.html#DynamoDB.Client.scan

Here is an example loop to get all the data from a DynamoDB table using LastEvaluatedKey:

import boto3
client = boto3.client('dynamodb')

def dump_table(table_name):
    results = []
    last_evaluated_key = None
    while True:
        if last_evaluated_key:
            response = client.scan(
                TableName=table_name,
                ExclusiveStartKey=last_evaluated_key
            )
        else: 
            response = client.scan(TableName=table_name)
        last_evaluated_key = response.get('LastEvaluatedKey')
        
        results.extend(response['Items'])
        
        if not last_evaluated_key:
            break
    return results

# Usage
data = dump_table('your-table-name')

# do something with data