> FKs are a performance impact. The fact they require indexes is likely fine, since those indexes are needed anyhow. But the lookup made for each insert/delete is an overhead.
This is not a valid argument at all and I'm concerned anyone would think it is.
If you have a foreign key, it means you have a dependency that needs to be updated or deleted. If that's the case, you will have an overhead anyway, the only question being whether it's at the DB level or at the application level.
I don't think there are many cases where there's any advantage to self-manage them at the application level.
> FKs don't work well with online schema migrations
This seems to be related only to the specific project that the issue is about if you read about the detailed explanation below.
This is not a valid argument at all and I'm concerned anyone would think it is.
If you have a foreign key, it means you have a dependency that needs to be updated or deleted. If that's the case, you will have an overhead anyway, the only question being whether it's at the DB level or at the application level.
I don't think there are many cases where there's any advantage to self-manage them at the application level.
> FKs don't work well with online schema migrations
This seems to be related only to the specific project that the issue is about if you read about the detailed explanation below.