How should I use DynamoDB table
depending on how you want to fetch the data. If you want to get all by item, then item as a primary key is a great choice. If you want to filter by item and url then i would add primary key Item and sort key url. If you want to have url and search for the item by url, i would add url as primary key and url as sort key. If you want to be able to do both, i would add primary key for item, sort key for url and then add new GSI with primary key url and sort key item.

I learned a lot about this from this conference: https://www.youtube.com/watch?v=jzeKPKpucS0 recommended.