Data Types
Autonomous Database allows most of the data types available in Oracle Database. To ensure the security and the performance of Autonomous Database, some data types are restricted.
The following data types are not supported or have limited support in Autonomous Database:
-
Large Object (LOB) data types: only SecureFiles LOB storage is supported. BasicFiles LOBs are automatically converted to SecureFiles LOBs.
-
Media types are not supported (Oracle Multimedia is desupported)
Checking and Setting MAX_STRING_SIZE
By default Autonomous Database uses extended data types and the value of
MAX_STRING_SIZE
is set to the value EXTENDED
.
With this setting you can specify a maximum size of 32767 bytes for the
VARCHAR2
, NVARCHAR2
, and RAW
data types. The default, EXTENDED
, is the recommended setting and
allows Autonomous Database to take full
advantage of database capabilities.
Use DBMS_MAX_STRING_SIZE
subprograms to check usage of
extended data types and to change the database to revert to the older style
STANDARD
, supporting a maximum size of 4000 bytes for
VARCHAR2
, NVARCHAR2
, and RAW
data types.
Using DBMS_MAX_STRING_SIZE
.MODIFY_MAX_STRING_SIZE
is a one-way change that cannot be reverted. After a database is switched back
to the STANDARD
style of supporting a maximum length of 4000
bytes for the VARCHAR2
, NVARCHAR2
, and
RAW
data types, you cannot re-enable
EXTENDED
data types.
The ADMIN user is granted
EXECUTE
privilege WITH GRANT OPTION
clause
on DBMS_MAX_STRING_SIZE
.
Oracle recommends that you do not GRANT EXECUTE
on this package
to other users.
-
Check whether your environment can be reverted to the old style,
STANDARD
behavior:SELECT * FROM TABLE(
DBMS_MAX_STRING_SIZE
.CHECK_MAX_STRING_SIZE('STANDARD'));See CHECK_MAX_STRING_SIZE Function for more information.
-
Check and correct all reported violations from Step 1, if applicable.
-
After fixing any reported violations found in Step 1, if you want to revert to a maximum length of 4000 bytes for
VARCHAR2
,NVARCHAR2
, andRAW
data types, use
as follows:DBMS_MAX_STRING_SIZE
.MODIFY_MAX_STRING_SIZEEXEC
DBMS_MAX_STRING_SIZE
.MODIFY_MAX_STRING_SIZE('STANDARD');See MODIFY_MAX_STRING_SIZE Procedure for more information.
See Extended Data Types for details on extended data types.
For a list of Oracle data types see Oracle Database SQL Language Reference.
Parent topic: Notes for Users Migrating from Other Oracle Databases