> A foreign key doesn't necessarily imply an index. If you are using postgres, you would have to add an index in addition to the foreign key, if you want one.

> A foreign key doesn't necessarily imply an index. If you are using postgres, you would have to add an index in addition to the foreign key, if you want one. Sure, I meant an index in which the key is primary. But, on second thought, that's probably me misreading the GP's message. > On delete cascade, depending on how many rows it cascades to, can be problematic because it's a very long running blocking operation. That's something one might want to do as a background operation and in batches. Although that won't make it faster. That can definitely be a problem (just like destructor deallocation stampedes in C++ or Rust). Still less risky than cascading manually and asynchronously, I suspect.