PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> now() and transaction_timestamp() are described as being equivalent in the
> guide
> https://www.postgresql.org/docs/11/functions-datetime.html#FUNCTIONS-DATETIME-CURRENT.
> However, using now() in a query can screw up a possible parallel plan since
> it's labeled PARALLEL RESTRICTED.
This is fixed in v12 and later, cf
https://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=07ee62ce9
regards, tom lane