That's what I said I think? "JSON" is a TEXT that is handled as a JSON string by `json_*` functions, while "JSONB" is a BLOB that is handled as an internal format by `jsonb_*` functions. You generally don't want JSONB in the application side though, so you do need a conversion for that.
Yes, but when you use the BLOB with jsonb functions, your application demands go from:
Read JSON from TEXT column.
Parse JSON into Internal Binary Format.
Run json_*() function on this format, which will Serialize Internal Binary Format to JSON as output.
To:
Read JSONB from BLOB column.
Run json_*() function on Internal Binary Format, which will serialize the Internal Binary Format to JSON as output.
Because:
The json_* and jsonb_* all accept _either_ JSON or JSONB as their input. The difference is jsonb_* functions also produces it as output. So even in the above case, if your function output is just being used to feed back into another table as a BLOB, then you can use the jsonb_* version of the function and skip the serialization step entirely.
Oh, you are right! I later looked at the draft documentation and realized that `json(b)_` only determines the output type. That said, it is still true that you need one more function call `json(...)` to retrieve a textual form of JSON which you do often need instead of JSONB.
> Run json_*() function on Internal Binary Format, which will serialize the Internal Binary Format to JSON as output
I don’t think that’s always correct (it is within this thread, which stated (way up) “if you’re always reading/writing the full blob”, but I think this discussion is more general by now). Firstly, it need not convert the full jsonb blob (example: jsonb_extract(field,'$.a.b.c.d.e'))
Secondly, it need not convert to text at all, for example when calling a jsonb_* function that returns jsonb.
(Technically, whether any implementation is that smart is an implementation detail, but the article claims this is
“a rewrite of the SQLite JSON functions that, depending on usage patterns, could be several times faster than the original JSON functions”
Of course (and I never said that), but if you need to store a JSON value in the DB and use a JSONB-encoded BLOB as an optimization, you eventually read it back to a textual JSON. It's just like having a UNIX timestamp in your DB and converting back to a parsed date and time for application uses, except that applications may handle a UNIX timestamp directly and can't handle JSONB at all.
