Regarding
current_timestamp
vs cast('now' as timestamp)
vs timestamp 'now'

I just hit this for myself. After reading the FB v2.1 release
notes I thought I understood that
timestamp 'now'
was the equivalent of
cast('now' as timestamp)

but after using it in a few places I found it is definitely not
the same. Nor is it quite the same as current_timestamp.
(I am currently assuming that "timestamp 'xxx'" is truly the
equivalent of cast('xxx' as timestamp) is most other cases.)

If this is intentional then probably the release notes need to
be updated. If this is not intentional, it is certainly
confusing, then a tracker item needs to be raised (I searched
but could not find one).

--
Geoff Worboys
Telesis Computing