On: Master Hexagonal Architecture in Rust

[mrkeen]

And that's fine.

If it's really big data I imagine I'd be in some kind of scalable no-SQL situation.

If it's not so big, Postgres will comfortably handle my access patterns even without joins.

If it's in the sweet spot where I need Postgres JOINS but I don't need no-SQL, well then, refactoring will be a breeze. I'll turn:

  class TaxCalculator {
    UserFetcher userFetcher;
    PurchasesFetcher purchasesFetcher;
    TaxResult calculate(UserId userId) {..}
  }

into:

  class TaxCalculator {
    UserPurchasesFetcher userPurchasesFetcher;
    TaxResult calculate(UserId userId) {..}
  }

which is backed by JOINS inside. And I can do this refactoring in two mutually-independent steps. I can make my Postgres class implement UserPurchasesFetcher without thinking about TaxCalculator, and vice versa.

And if it's about the data integrity that JOINs could notionally provide, I no longer believe in doing things that way. The universe doesn't begin and end within my Postgres instance. I need to be transacting across boundaries, using event sourcing, idempotency, eventual consistency and so forth.