The CHAR_LENGTH64 function returns
an unsigned 64-bit value containing the character length of the LONG
VARCHAR column parameter, including the trailing blanks.
Remarks
CHAR_LENGTH64 also supports LONG
VARCHAR variables of any data size.
If you are licensed to use the Unstructured Data Analytics functionality, you can
use this function with large object data. See CHAR_LENGTH64 Function in
Unstructured Data Analytics.