[simonw]

Triggers protect you against bugs.

If your application logic needs to remember to update a denormalized column somewhere it's very easy for a bug to slip in in the future when someone adds a new piece of Python code but forgets to update the denormalized column.

With triggers you can eliminate that source of bugs entirely.

This is even more valuable if you have more than one system interacting with a single database.

[SOLAR_FIELDS]

Triggers can also be significantly more performant depending on what you are doing.

But yeah having the business logic split like this is a hard sell. There needs to be an extremely good reason to do it. It adds developer overhead because not only do you have to maintain another test harness and deal with an entirely separate system encapsulating yours, every time you touch business logic you’re now wasting some brainpower deciding where it should live.

[paulryanrogers]

I did this with robust DB constraints and selective use of triggers and stored functions. It can feel like a strait jacket long term. Though it did help protect against less competent DBAs breaking things and avoid some footguns.