Multiple databases versus single database with multiple schemas

Use Single Database with Schemas If:
Your workload is medium-sized and manageable within one database.
Cross-layer queries are frequent, and query simplicity is a priority.
You want to minimize administrative overhead.

Use Multiple Databases If:
You have very high data volumes and concurrent queries.
Compute isolation is critical to prevent one layer’s workload from impacting another.
You require distinct configurations for each layer (e.g., filegroups, recovery models).



For your case, where data flows through multiple layers (raw → augmented → aggregate), start with a single database and multiple schemas. Monitor the performance and, if resource contention becomes an issue, consider splitting into multiple databases.