The datetime(template) function is the only feature remaining to be implemented. It requires implementation of the PosgreSQL Date/Time Formatting language for parsing and perhaps formatting.

Also use the parsing to improve the parsing of datetime values to be more tolerant of formatting differences. See the // pg: comments in exec/pg_test.go, but it's stuff like no leading zeros for days, months, and offsets, and extra spaces between values (especially time zones).

Relevant bits of the Postgres source:

• parse_datetime: Called by the jsonpath executor to parse dates and times.
• do_to_timestamp is called by parse_datetime
• parse_format is called by do_to_timestamp and does the actual parsing
• DCH_to_char appears to be the function that formats a datetime value. Not sure if this functionality is needed or not.