Database per Service: A Solution

The previous lesson showed how one shared database couples services together. The fix is a single rule with large consequences. This lesson states the rule and shows what it changes right away.

The Rule

Each service owns a private data store, and no other service may touch its tables. Every other service reaches that data only through the owning service's API.

That is the whole pattern. "Private" means the schema (the set of tables, columns, and types) belongs to one service and one team. No other code connects to the database, runs queries against it, or even knows its table names.