With the introduction of Oracle 12c, the maximum string size for NVARCHAR2, RAW, and VARCHAR2 data types can be increased or extended.
To implement these extended data types, the server must be configured by setting the MAX_STRING_SIZE intialization parameter to EXTENDED. (See Oracle product documentation for details.)
The driver supports the functionality of the extended data types in the following manner.
NVARCHAR2
If MAX_STRING_SIZE=EXTENDED, the driver supports a maximum string size of 32766 bytes.
If MAX_STRING_SIZE=STANDARD, the driver supports a maximum string size of 4000 bytes. 4000 bytes is the default maximum for Oracle 12c and the maximum for previous database versions.
RAW
If MAX_STRING_SIZE=EXTENDED, the driver supports a maximum string size of 32767 bytes.
If MAX_STRING_SIZE=STANDARD, the driver supports a maximum string size of 2000 bytes. 2000 bytes is the default maximum for Oracle 12c and the maximum for previous database versions.
VARCHAR2
If MAX_STRING_SIZE=EXTENDED, the driver supports a maximum string size of 32767 bytes.
If MAX_STRING_SIZE=STANDARD, the driver supports a maximum string size of 4000 bytes. 4000 bytes is the default maximum for Oracle 12c and the maximum for previous database versions.