Getting the length in characters of a blob sub_type text

[Mark Rotteveel]

Is there a way to get the length in characters of a blob sub_type text
with only the blob id? Preferably, with an API / wire protocol call, and
not resorting to having to execute SQL.

Specifically, I'm looking at being able to fulfill JDBC's
java.sql.Clob.length() for UNICODE_FSS/UTF8 and potentially other
variable length character sets without having to resort to materializing
the entire blob locally to determine the number of characters.

Mark
--
Mark Rotteveel