Support for Grafast plan resolvers

[ronkkol]

Is your feature request related to a problem? Please describe.

We have a large graphql-modules application that uses DataLoader to deal with N+1 problems for database requests. As the requests are asynchronous, we still encounter problems with memory usage. Promises still instantiate in an N+1 way, even though they might get resolved with a smaller number of DB requests.

We looked into Grafast which introduces synchronous plan resolvers instead of traditional GraphQL resolvers to address this problem. Unfortunately, graphql-modules' schema builder doesn't seem to support plans in the schema for modules.

Describe the solution you'd like

I'd like interoperability with Grafast plans in schemas built by graphql-modules. Instead of the schema builder handling typeDefs and resolvers, it would be nice to support plans out-of-the-box.

Describe alternatives you've considered

Grafast's team suggested adding plans under the resolvers' extensions in the following way:

  resolvers: {
    Query: {
      user: {
        extensions: {
          grafast: {
            plan(_, { $id }) {
              return object({
                _id: $id,
                username: constant('jhonFromGrafast')
              });
            }
          }
        }
      }
    }

Unfortunately, when modifying a module's resolvers that way, the final schema does not seem to have the extensions.

Additional context

We use graphql-modules currently and hopefully grafast as well in the future as GraphQL envelop plugins.

[benjie]

General support for extensions would be beneficial beyond Grafast, e.g. for https://github.com/slicknode/graphql-query-complexity/blob/HEAD/src/estimators/fieldExtensions/README.md