alt Hacker NewsWouldn't you consider defining the schema doing the domain modeling?
I think ORMs do too much. I want to control the querying, or, more precisely, I want to control the SQL that goes to the planner. The good ones largely do allow for this, but I can't think of one that has innate support for vendor-specific features.
What I do appreciate is that they handle the boilerplate like managing connections, preparing statements, setting parameter values, and mapping database types back to client types.
Replies
> Wouldn't you consider defining the schema doing the domain modeling?
No, because if the schema is the only reference for data models, developers on any sufficiently large team will come up with extremely widely varied queries to access equivalent information. Those are more likely to be incorrect (someone with domain expertise on one set of tables might miss that authoritative data needs to be joined/queried from elsewhere), harder to update when schemas change (more client code changes to alter and test), and more likely to miss performant techniques to query data.
Those can all be addressed with disciplined use of views or common utility SQL snippets or functions, but ORMs also get you to that point without requiring as much ongoing discipline, care, and feeding.
> Wouldn't you consider defining the schema doing the domain modeling?
To an extent, yes.
But to the extent that a so-called impedance mismatch exists, this is going to put your domain model on the faraway/difficult side of that impedance mismatch.
And will result in your domain model existing in an (on average) less expressive language which is more difficult to test.