Major Description
Currently the only way to evaluate a path expression on a JSON object is through get_json_object. If there are many fields in the JSON object need to be extract, we have to call this UDF multiple times.
There are many use cases that get_json_object needs to be called many times in one query to convert the JSON object to a relational schema. It would be much desirable if we have a JSON UDTF that supports the following syntax:
select a.id, b.* from a lateral view json_tuple(a.json_str, '$.f1', '$.f2', ..., '$.fn') b as f1, f2, ..., fn
where the json_table function only scans the json_object once and return a set of tuple of (f1, f2,..., fn).