How Would You Use Glue SQL to Merge Data from Various Sources in an AWS Environment?

Introduction

GraphQL has emerged as a compelling alternative to REST for building APIs in modern web applications. Since its release as an open standard by Facebook in 2015, GraphQL has been adopted by major technology companies and is increasingly used in production applications of all sizes. For Swiss development teams evaluating API architecture choices, understanding the genuine trade-offs between GraphQL and REST is essential for making the right decision for each project. In this article, we provide a balanced comparison of the two approaches and explain when each is most appropriate.

Problem

REST APIs, while well-understood and widely used, have specific limitations that become significant in certain application architectures.

Over- and Under-Fetching

• REST APIs typically return fixed data structures for each endpoint, meaning clients either receive more data than they need (over-fetching) or must make multiple requests to assemble the data they need (under-fetching).
• In mobile applications and low-bandwidth environments, unnecessary data transfer has a direct impact on performance and battery consumption.
• Multiple round-trips to assemble a complete view of the data increase latency, particularly for users in Switzerland accessing APIs hosted abroad.

API Evolution

• Versioning REST APIs (v1, v2, v3) is complex and creates long-term maintenance burdens as multiple API versions need to be supported simultaneously.
• Adding new fields to REST responses can break clients that are not designed to handle unexpected fields; removing fields is a breaking change that requires versioning.
• Frontend teams often have to wait for backend teams to add new API endpoints before they can build new features — creating dependency bottlenecks.

Solution

Understanding the core characteristics of each approach enables informed, project-specific API architecture decisions.

1. GraphQL Characteristics

• Clients specify exactly the fields they need in a query, receiving precisely that data and nothing more — eliminating over- and under-fetching.
• A single GraphQL endpoint handles all queries and mutations; the schema defines what operations are available.
• Strong type system and schema introspection enable excellent developer tooling, automatic documentation, and type-safe client code generation.
• Schema evolution is handled through deprecation rather than versioning — fields can be marked as deprecated and removed in a future release without breaking existing clients immediately.
• Subscriptions enable real-time data updates over WebSocket connections — a capability that is complex to add to REST APIs.

2. REST Characteristics

• Resource-oriented architecture maps naturally to CRUD operations and is well-understood by virtually every developer and tool in the ecosystem.
• HTTP caching works naturally with REST — GET requests can be cached by CDNs and browsers without custom configuration.
• Stateless and simple — REST APIs are easy to reason about, test, and monitor.
• Broad tooling support — every HTTP client, API testing tool, and monitoring solution supports REST out of the box.
• For simple, resource-oriented APIs with predictable access patterns, REST is faster to implement and easier to maintain.

3. Decision Framework

• Choose GraphQL when: you have multiple clients (web, mobile, third-party) with different data needs; your data is deeply relational; you want to give frontend teams more autonomy; or you need real-time subscriptions.
• Choose REST when: you are building a simple CRUD API; you need extensive HTTP caching; your team has limited GraphQL experience; or you are building a public API where simplicity and broad client support matter.
• For Swiss payment integrations (Twint, PostFinance) and third-party API consumption, REST is almost always the appropriate choice — these APIs expose REST interfaces and are consumed rather than designed.

4. Implementation Considerations

• GraphQL implementations in PHP (e.g. with Laravel + Lighthouse) and Node.js (Apollo Server) are mature and production-ready.
• N+1 query problems are a common GraphQL performance pitfall — address these using DataLoader or similar batching mechanisms from the outset.
• GraphQL's flexibility requires careful access control design to prevent clients from requesting more data than they are authorised to see.
• REST API caching at the CDN layer is straightforward; GraphQL requires additional caching strategies (persisted queries, response caching).

Benefits Summary

• GraphQL benefits: precise data fetching, frontend autonomy, self-documenting schema, real-time subscriptions, reduced API versioning complexity.
• REST benefits: simplicity, HTTP caching, universal tooling support, easy monitoring, and lower learning curve.
• Both approaches can be used in the same application — REST for external-facing public APIs, GraphQL for internal data-intensive frontend-backend communication.

Practical Example

A Swiss e-commerce platform serving both a web application and a mobile app adopted a hybrid approach: a GraphQL API for their internal frontend-to-backend communication (enabling the web and mobile teams to query exactly the data they needed without back-end changes), and REST webhooks for receiving payment confirmations from Twint and PostFinance. The GraphQL adoption reduced average API response size by 60% for mobile clients and eliminated a backlog of "please add this field to the API" requests from the frontend team.

Conclusion

GraphQL and REST are complementary tools for different situations — the question is not which is better overall, but which is better for each specific use case. REST remains the right choice for simple, resource-oriented APIs and public interfaces. GraphQL delivers compelling advantages for complex, data-intensive applications with multiple client types. For Swiss development teams, the pragmatic path is to default to REST for new projects, adopt GraphQL when the specific advantages it provides are genuinely needed, and resist the temptation to choose either purely on the basis of current fashion.