Cool project.I haven’t looked at the code too much(yet). I’d be curious to know how you’re handling some of the more wiry edge cases when it comes to following foreign key constraints. Things like circular dependencies come to mind. As well as complex joins.
I feel ok posting this because it’s archived, but this problem is basically what we designed for with Neosync [1].
It was probably the hardest feature to fully solve for the customers that needed it the most, which were the ones with the most complex data sets and foreign key dependencies.
To the point where it was almost impossible to do this, at least with syncing it directly to another Postgres database with everything in tact. Meaning that if on the other side you want another pg database that has all of the same constraints, it is difficult to ensure you got the full sliced dataset. At least the way we were thinking about it.
[1]: https://github.com/nucleuscloud/neosync
3/5/2026
at
5:21:24 PM
that is a valid point. dbslice finds cycles in the fk graph and usually resolves them by nulling a nullable fk for insert order, then patching it back with deferred updates after inserts. if a cycle has no nullable fks, postgres output can still work when deferred fk checking is enabled and the cycle constraints are deferrable, otherwise it fails fast with a clear error.traversal automatically pulls in parent records so you don’t end up with dangling references, and a validator (enabled by default) can double-check the slice before output. for complex joins, you can opt into subqueries in seed where clauses.
it covers a lot of messy cases, but i won’t claim it’s fully solved yet. there’s no automatic discovery of relationships that only exist in app code (beyond heuristic hints), and real production schemas will still surface new edge cases. it’s still early-stage, so the more people test it on messy production-like datasets, the faster i can iron those out.
i would also love to hear what you think of the implementation if you check out the code.
by nabroleonx