Hello all, happy holiday season =)
I have been reading through the tutorial materials on the Calcite site +
repo, and have watched the BOSS 2021 YouTube recording covering the Lucene
implementation (excellent workshop, by the way -- thank you!)
I am interested in working on a side project for fun & learning, but I'm
not familiar with this area, and also don't have a formal education.
My idea is to try to implement an auto-generated GraphQL API on top of
Calcite data sources.
Roughly the thought is something like:
1) Calcite adapter provides schema information/metadata
2) Some class/function consumes the schema, and generates the corresponding
GraphQL type and CRUD resolvers for it:
- IE, for some table *"user"*, you might have *"find_user()"*,
*"insert_user()"*, *"update_user()"*, and *"delete_user()"*, which take
SQL-like filter & update expressions
3) The resolver functions translate the GraphQL query AST -> Calcite
query/expression AST, which is passed on to the adapters to execute
I am sure it is not so easy, but hopefully this gets the gist across:
==================================================
*[Server]: *makeGQLSchemaFromCalciteDataSources() --->
GraphQL schema ---> *[Client receive]*
*[Client]:* graphqlQuery("...") --->
* [Server receive]:* convertGQLQueryAstToRelExpr(query) --->
Execute expression against
adapters --->
Result ---> *[Client]*
==================================================
As a silly example (or if you've never heard of GraphQL), taking a possible
schema for a "collaborative" Todo app:
*user <-> user_todos <-> todo*
Here is what a GQL query might look like, and an example of the generated
Postgres SQL query + EXPLAIN ANALYZE plan for it (from a tool that does
this type of thing already):
- https://gist.github.com/GavinRay97/c667e71b595037388e72924a78708d86
I find this a really interesting problem, because of Calcite's ability to
dispatch a single query to multiple data sources.
This fits nicely with GraphQL's query model, because you can write things
like:
query {
> user_from_db1(where: { name: { eq: "Person" } }) {
> ...<fields>
> todos_from_csv_file {
> ...<fields>
> }
> }
And then it is the server's job to fetch the right data from the right
places, efficiently.
I apologize if any of this (or the formatting) breaks mailing-list
etiquette, I've not used one before.
Best wishes,
Gavin Ray
