Imperative code run on the DB (i.e. triggers) seems entirely in-scope. It's an incredibly powerful tool provided natively by the DB, intended to be used for ex

Imperative code run on the DB (i.e. triggers) seems entirely in-scope. It's an incredibly powerful tool provided natively by the DB, intended to be used for exactly this kind of custom constraint. Whether it's begin/end with imperative code or modeled some other way declarative seems absolutely, 100% irrelevant to me - it's the perfect implementation detail, it could have been done with `create unique index max 2 (x, y) on mytable` and you'd never know. If you meant to prevent "all inserts are now [run this stored procedure / multi-statement operation / transaction with N steps]", then yeah - I agree that runs counter to "normal" use in most cases. It's certainly dramatically more error prone. Triggers don't need this though. re chain of relations: I haven't poked too hard in this direction in SQLite, but I do totally believe its query planner isn't too sophisticated. And though you can get pretty good data locality with fancy design around the DB, you certainly won't get good locality just by inserting a bunch of data and running queries.