The problem sounds like something that could be solved with a GIST index. EdgeDB doesn't yet have a way to specify the index type, though, mostly because we aren't sure what would be the best way to do it without things becoming too Postgres-specific in schemas.
This is not something we plan to do in the near future, but it’s also not outside the realm of possibility. We picked Postgres because of its power, quality and unparalleled extensibility, but we are also very careful to not leak any implementation details into our interfaces.
> EdgeDB does not treat Postgres as a simple standard SQL store. The opposite is true. To realize the full potential of the graph-relational model and EdgeQL efficiently, we must squeeze every last bit of functionality out of PostgreSQL's implementation of SQL and its schema.
I don't see how this and what you're saying can both be true at the same time. Is EdgeDB tightly coupled to the implementation of PostgreSQL, or isn't it? Is there really a chance that EdgeDB could support other databases, or not really? I don't think there's anything wrong with the answers being "yes" and "no", respectively; that's actually what I'd expect. It would be more unusual to try to do this in an implementation-agnostic way.
I think what they mean by this is that EdgeDB's query language should not be coupled to Postgres, but EdgeDB itself should use Postgres specific SQL features to maximise performance - so you couldn't drop in MariaDB without changing code in EdgeDB, but in theory you could write another backend that takes the same queries and uses MariaDB or MongoDB or something custom under the hood.