Hi,
about the datetime issue: as far as I know, JSON does not define a
serialization format for dates and timestamps.
On the other hand, YAML (as a superset of JSON) already supports a
language-independent date(time) serialization format
(http://yaml.org/type/timestamp.html).
I haven't had a glance into the SQL/JSON standard yet and a quick search
didn't reveal anything. However, reading your test case here
https://github.com/postgrespro/sqljson/blob/5a8a241/src/test/regress/sql/sql_json.sql#L411
it seems as if you intend to parse all strings in the form of
"YYYY-MM-DD" as dates. This is problematic in case a string happens to
look like this but is not intended to be a date.
Just for the sake of completeness: YAML solves this issue by omitting
the quotation marks around the date string (just as JSON integers have
no quotations marks around them).
Regards,
Sven