According to the
docs, the semantics of "
AT TIME ZONE" on timestamps is convert back and forth between their "with timezone" and "without timezone" variants.
As I see it, the issue is in most programming languages --- informal English, "as" would seem to imply an idempotent conversion operation, not an inverse operation! As the reply to that email says, "It's really two distinct operations depending on whether the input is a timestamp with or without timezone." That avoids a foot-gun of confusing "toggling" behavior.
I understand that the semantics of "AT TIME ZONE" are fixed per the SQL spec, and so we are stuck with them. But on the model of timezone(zone, timestamp) which
with_timezone(zone, timestamp
without_timezone(zone, timestamp
where giving them arguments with of the wrong type (e.g. the wrong with-timezone-ness) is simply and error.
SQL has lots of accumulated warts, and this hardly scratches the surface of what would be needed to make it truely "idiot proof", but it strikes me a simple, easy to implement new feature with clear benefits.
Curious what you all think,
John
