Enabling the New Extended Data Type Capability
Enabling a system to take advantage of the new extended data types requires specific upgrade actions.
Oracle Database 12c introduced MAX_STRING_SIZE to control the maximum size of VARCHAR2, NVARCHAR2, and RAW data types in SQL. Setting MAX_STRING_SIZE = EXTENDED enables the 32767 byte limit introduced in Oracle Database 12c.
To be able to set MAX_STRING_SIZE = EXTENDED, you must set the COMPATIBLE initialization parameter to 12.0.0.0 or higher
In addition, you must run the script utl32k.sql script while the database is open in upgrade mode so that you invalidate and recompile objects that are affected by the change in data type sizes. For example:
CONNNECT SYS / AS SYSDBA
SHUTDOWN IMMEDIATE;
STARTUP UPGRADE;
ALTER SYSTEM SET max_string_size=extended;
START $ORACLE_HOME/rdbms/admin/utl32k.sql
SHUTDOWN IMMEDIATE;
STARTUP;Caution:
You can change the value of MAX_STRING_SIZE from STANDARD to EXTENDED. However, you cannot change the value of MAX_STRING_SIZE from EXTENDED to STANDARD. By setting MAX_STRING_SIZE = EXTENDED, you are taking an explicit action that can introduce application incompatibility in your database.
See Also:
Oracle Database Reference for complete information about MAX_STRING_SIZE, including recommendations and procedures