You'd use it whenever you're building an application on Cloudflare Workers and you need to store data. D1 provides you with a SQL database. It's based on SQLite, so it's designed for relatively small datasets but can serve them very quickly from the edge.
Note there are several alternatives here, too. Workers Durable Objects[0] provide a lower-level primitive for building advanced distributed systems. But D1 is easier to use for typical use cases. For blob storage you might use R2[1]. And for large databases Workers can easily integrate with several serverless database providers.[2]
Note there are several alternatives here, too. Workers Durable Objects[0] provide a lower-level primitive for building advanced distributed systems. But D1 is easier to use for typical use cases. For blob storage you might use R2[1]. And for large databases Workers can easily integrate with several serverless database providers.[2]
[0] https://blog.cloudflare.com/introducing-workers-durable-obje... [1] https://www.cloudflare.com/products/r2/ [2] https://blog.cloudflare.com/announcing-database-integrations...