Architecting Polyglot Persistence: When to use Cosmos DB SQL API vs Gremlin Graph

Use SQL API for high-scale document storage with known access patterns; use Gremlin for traversing complex, multi-hop relationships.

While both run on the same underlying Cosmos DB engine, the data modeling differs. SQL API is optimized for document-centric workloads where queries typically filter on properties. Gremlin (Graph) is optimized for 'traversal'—queries like 'Who are the friends of my friends who like Sushi?'. In Graph, the relationship (Edge) is a first-class citizen. Architecturally, you might use SQL API for the core user data and project specific relationships into a Gremlin container for social or recommendation features.