pg_graphql VS assert-combinators

Hi, I'm the author of Supabase GraphQL (pg_graphql)

One of the restrictions of composite types is that they can not contain an instance of themselves. So unfortunately, this is not currently possible.

I had this issue when trying to implement an AST type for pg_graphql[1] back when it was written in SQL [2]. In the end we used a JSON type which was much less constrained. That might be solvable using pg_jsonschema [3] if you really wanted to have a good time though

[1] https://github.com/supabase/pg_graphql

It’s something that’ll come in future, but nothing available yet: https://github.com/supabase/pg_graphql/issues/17

But... If you're looking for Graphql/Postgres, maybe look at https://github.com/supabase/pg_graphql which popped onto my radar yesterday, but I have no experience with it.

Check out some of the generated queries this extension [1] pumps out and you might have an answer.

[1] https://github.com/supabase/pg_graphql

hey HN, supabase ceo here. I'm really excited about this release.

Our GraphQL implementation is built on top of pg_graphql[0], a PostgreSQL extension we open-sourced a few months ago. The implementation works with a lot of native PG functionality (like Row Level Security). You can also do a some neat things with PG GRANTS, enabling/disabling access to different tables/columns to effectively serve a different GraphQL API depending who is "logged in".

On Supabase, the extension is served via PostgREST[1] using the public PostgreSQL function exposed by pg_graphql. PostgREST exposes PG functions as RPC routes (in our case we also map /rest/v1/rpc/graphql => /graphql/v1)

I'll ping the main dev (@oli_rice) and make sure he is here to answer any technical questions. This is just one of the exciting features we're launching this week. Stay tuned for one of our most-requested features later this week.

[0] pg_graphql: https://github.com/supabase/pg_graphql

[1] PostgREST: https://postgrest.org/

We use in prod variant of no 1. [0]. Why? Because:

* it's extremely lightweight (built on pure, functional combinators)

* it allows us to use more complex patterns ie. convention where every json field ends with Json which is automatically parsed; which, unlike datatype alone, allows us to create composable query to fetch arbitrarily nested graphs and promoting single [$] key ie. to return list of emails as `string[]` not `{ email: string }[]` with `select email as [$] from Users` etc.

* has convenience combinators for things like constructing where clauses from monodb like queries

* all usual queries like CRUD, exists etc. and some more complex ie. insertIgnore, merge1n etc has convenient api

We resort to runtime type assertions [1] which works well for this and all other i/o; runtime type assertions are necessary for cases when your running service is incorrectly attached to old or future remote schema (there are other protections against it but still happens).

[0] https://github.com/appliedblockchain/tsql

[1] https://github.com/appliedblockchain/assert-combinators

We use not so much frameworks but combination of lightweight libraries:

- runtime assertions [0] - to map unknown values at i/o boundary into statically typed code (rpc input parameters, sql results etc)

- template based sql combinators to sanitize sql/generate sql [1]

- jsonrpc over websockets - for bidirectional comms between f/e and b/e

[0] https://github.com/appliedblockchain/assert-combinators

[1] https://github.com/appliedblockchain/tsql

Types can be asserted at runtime (parsed) at IO boundaries (reading http request or response, websocket message, parsing json file etc). Once they enter statically type system they don't need to be asserted again.

The difference it makes is illusion of type-safety vs type-safety this article touches on.

You can try to bind service with client somehow but in many cases this will fail in production as you can't guarantee paired versioning, due to normal situations by design of your architecture or temporary mid-deployment state or other team doing something they were not suppose to do etc. It's hard to avoid runtime parsing in general.

Functional combinators [0] or faster [1] with predicate/assert semantics work very well with typescript, which is very pleasant language to work with.

[0] https://github.com/appliedblockchain/assert-combinators

[1] https://github.com/preludejs/refute

Once i/o boundaries are parsing unknown types into static types, your type safety is guaranteed.

[0] https://github.com/appliedblockchain/assert-combinators