Implementing a single resolver is not difficult. The trouble starts when you need your server to operate fast and efficiently on a broad range of query patterns.
The switch from REST to GraphQL moves the burden of data fetching from client to server. As GraphQL is dynamic in nature you have to handle any query the frontend might send and can no longer rely on the static shape of a REST API when optimising your data access pattern.
The fundamental issue is that there is a big gap between the GraphQL API you want to expose and the underlying data layer you have available. Sometimes you need to combine data from several underlying databases making it critically important to perform data queries in the right order and in parallel when possible.
Think of Prisma as a GraphQL database query engine that analyses every incoming query in order to generate an optimal execution plan for your underlying databases.
The switch from REST to GraphQL moves the burden of data fetching from client to server. As GraphQL is dynamic in nature you have to handle any query the frontend might send and can no longer rely on the static shape of a REST API when optimising your data access pattern.
The fundamental issue is that there is a big gap between the GraphQL API you want to expose and the underlying data layer you have available. Sometimes you need to combine data from several underlying databases making it critically important to perform data queries in the right order and in parallel when possible.
Think of Prisma as a GraphQL database query engine that analyses every incoming query in order to generate an optimal execution plan for your underlying databases.