[doctor_eval]

So many people I encounter seem to think it’s the code that’s important when building the back end of an application. You see this when people discussing database schemas start comparing, say, rails to hibernate. But ORMs emphasise code instead of data, which in my experience is a big mistake.

In my experience, getting the data structures right is 99% of the battle. If you get that right, the code that follows is simple and obvious.

For database applications, this means getting the schema right. To this end, I always start with the underlying table structures, and only start coding once I understand how the various tables are going to interact.

Sadly, too many people think of the database as the annoying hoops we jump through in order to store the results of our code. In my world, the code I write is the minimum required to safely manipulate the database; it’s the data that counts.

Some people seem to think I’m weird for starting with the database (and for using plpgsql), but I think it’s actually a superpower.

[jupp0r]

This is true for in memory data as well. Object oriented programming is great for some problems, but it's also limiting the way we think about data by putting it close to the code operating on it. ORMs do the same to databases by pretending that rows are objects when that's only one way of modeling your problem.

[jimbokun]

It’s part of the dirty little secret of why document databases and other NoSQL systems became popular.

Required even less up front thinking about how to model your data. Throw some blobs of JSON into Mongo or whatever, and worry about the rest later.

[thom]

It wasn’t always code first - you mention Hibernate but 15-20 years ago it was entirely feasible to inherit a database schema or design one up front, and then create performant metadata mappings to a usable object model. That sort of practise was tainted by the Bad Enterprise brushes of verbosity and XML in general, and so everyone moved to some flavour of active record. This allowed programmers to write less code and fit it into neater boxes, at a time when there was enormous demand for basic CRUD web apps, but a lot of power and expressiveness was lost.

Somewhat ironically, many modern enterprises have peeled all the way back to SQL for a huge amount of logic anyway, so I don’t think we’re done caring about database schemas quite yet.

[doctor_eval]

You are absolutely correct; my previous business ended up ejecting almost all database logic from Java ORMs, and moved almost everything to straight SQL manipulated by stored procedures. Doing so resulted in a significant performance and productivity increase, relative to all the layers of nonsense we used to jump through.

One of the difficulties of doing this was that the tooling isn’t great. We had to write our own tools to make it work, but the benefits of going back to SQL were more than worth it.

(Many years later I made an open source version of that tooling, https://github.com/pgpkg/pgpkg)

[sjwhevvvvvsj]

A simple function call as a wrapper for a well optimized sql query just can’t be beat for performance. I have never understood why anybody would use an ORM, it’s usually as much work to learn and maintain them as SQL.

[doctor_eval]

Yes, agreed. I spent a few years away from the technical side of things and when I jumped back in I was horrified at the amount of complexity these things added.

In Java it appeared that JPA was trying to completely abstract the database into the JVM, but it just meant a million annoying cache problems, terrible performance, a serious cognitive load, and poor interoperability with other database users.

The guy who promoted this internally kind of wrote the problems off as being a "leaky abstraction" but it wasn't even that. JPA entirely failed to resolve the object-relational "impedance mismatch" by failing to acknowledge that the boundary between the database and the application is actually a legitimate surface, like any other API surface.

What a nightmare it was.

[sjwhevvvvvsj]

Yup - and you can’t code your way to real scale either. At real scale the game is all about data structures. Code just gets them from A to B.

Or as they say at Google, the job of SWE is “moving protos”.