I think the `json_ntype` and `json_nextract` functions are good. The subtype codes used for JSON should be documented, though. JSON structures can sometimes be helpful inside of another record (especially when you want to interact with other programs that use JSON formats), but there are the problem involving JSON too: JSON does not use 64-bit integers, and it uses Unicode, and cannot store blobs effectively (except by encoding them as hex, base 64, etc). Not all data is text (and even that which is, isn't necessarily Unicode text).