Script to export Dynamodb records from old table and migrate those records to new dynamodb table.

export-dynamodb-table.py

import boto3
import json

SOURCE_TABLE_NAME = "--replace-source-tablename--"
DESTINATION_TABLE_NAME = "--replace-destination-tablename--"
# export records in tableName.json file
OUTPUT_FILE = f"{SOURCE_TABLE}.json"
# replace region
AWS_REGION = "us-west-2" 
failed_updates = []

dynamodb = boto3.resource('dynamodb', region_name=AWS_REGION)


# export table records from dynamodb into a json file
def exportTableRecords():
    print("Starting to export table records")
    table = dynamodb.Table(SOURCE_TABLE_NAME)
    response = table.scan()
    data = response['Items']

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

    with open(OUTPUT_FILE,"w+") as f:
        json_data = json.dumps(data)
        f.write(json_data)
        print(f"Table data is exported to ${OUTPUT_FILE}, kindly verify")
        
exportTableRecords()


```json
// data is exported in this format
[{
    "company": "ABC",
    "Address": "San fransisco
},{
    "company": "DEF",
    "Address": "Seattle"
}]
```
# import table records from json file into dynamodb
# Refactor the data before inserting into new table
def importTableRecords():
    print("Starting to import table records")
    table = dynamodb.Table(DESTINATION_TABLE_NAME)

    # read the data from json file
    with open(OUTPUT_FILE, "r") as f:
        json_data = f.read()
        items = json.loads(json_data)

    # insert into dynamo db
    with table.batch_writer() as batch:
        for item in items:
            try:
                # conditionally put only if organization is not present
                table.put_item(
                    Item={
                        "organization": item["company"],
                        "organizationAddress": item["address"]
                    },
                    ConditionExpression="attribute_not_exists(organization)"
                )

            except Exception as e:
                print(f"!!!Failed to insert because of error : {e}")
                failed_updates.append(item)
    
    if failed_client_channel_arns:
        print('Failed to update  organization: ', failed_updates)

importTableRecords()