COMPATIBLE

COMPATIBLE enables you to use a new release of Oracle while ensuring the ability to downgrade the database to an earlier release.

Property	Description
Parameter type	String
Syntax	COMPATIBLE = release_number
Default value	Oracle AI Database 26ai, Release Update 23.6 or later: 23.6.0 Oracle AI Database 26ai, Release Update 23.5: 23.5.0 Oracle AI Database 26ai, Release Update 23.4: 23.4.0
Modifiable	Oracle AI Database 26ai, Release Update 23.9 or later: Yes, with restrictions. See "Dynamic Modification of the COMPATIBLE Initialization Parameter" at the end of this section. Oracle AI Database 26ai, Release Update 23.8 or earlier: No
Modifiable in a PDB	No
Range of values	19.0.0 to default release Values must be specified as at least three decimal numbers with each number separated by a dot, such as 23.6.0 or 23.6.0.0
Basic	Yes
Oracle RAC	Multiple instances must have the same value.

The COMPATIBLE parameter specifies the Oracle version number that the database disk format must be compatible with. The database can be downgraded to the version specified in the COMPATIBLE parameter or any later version.

Setting COMPATIBLE ensures that new features do not write data formats or structures to disk that are not compatible with the earlier release, preventing a future downgrade. Features that require a higher value of COMPATIBLE to work correctly may be restricted or disabled to ensure downgrades are possible.

Typically, users keep COMPATIBLE unchanged when upgrading their Oracle software. After upgrade, users will run the new release of the Oracle software for a few weeks to ensure that the new release is working correctly. Afterwards, users can choose to update COMPATIBLE to the latest version to take advantage of the new features.

The following guidelines apply when applying a Release Update or Release Update Revision:

• For Oracle AI Database 26ai:

  The value of the COMPATIBLE parameter should be changed when you apply a Release Update (RU) only under the following circumstance: You are running the Oracle AI Database 26ai, RU 23.4, and you have explicitly set COMPATIBLE to any value (including the default value of 23.4.0). You then apply a Release Update. In this case:

  • If you apply RU 23.5, then you must set the value of COMPATIBLE to 23.5.0 in order to use all of the features of Oracle AI Database 26ai, including the features introduced in RU 23.5.

  • If you apply RU 23.6 through 23.26.0, then you must set the value of COMPATIBLE to 23.6.0 in order to use all of the features of Oracle AI Database 26ai, including the features introduced in RU 23.6.

  The value of the COMPATIBLE parameter should not be changed when you apply a Release Update Revision (RUR) in Oracle AI Database 26ai.

• For Oracle Database 21c, Oracle Database 19c, and Oracle Database 18c:

  The value of the COMPATIBLE parameter should not be changed for an RU or an RUR. For example, assume you are running Oracle Database 21c and the value of COMPATIBLE is 21.0.0. You then apply Oracle Database 21c, RU 21.4. Do not set the value of COMPATIBLE to 21.4.0; leave it set to 21.0.0.

Dynamic Modification of the COMPATIBLE Initialization Parameter

Starting with Oracle AI Database 26ai, RU 23.9, you can dynamically modify the value of COMPATIBLE for all sessions in the current instance. This allows you to use database features that require a COMPATIBLE setting that is greater than your current setting, without having to restart the database instance.

You can dynamically modify the COMPATIBLE setting by using the SQL command ALTER DATABASE SET DOWNGRADE COMPATIBILITY.

For example, assume you are running Oracle AI Database 26ai, RU 23.26.0, and COMPATIBLE is set to 23.4.0. If you would like to use features that are available with a COMPATIBLE setting of 23.6.0, without having to restart the database instance, you can dynamically update the COMPATIBLE setting as follows:

SQL> SHO PARAMETER COMPATIBLE

NAME                      TYPE        VALUE
------------------------- ----------- -------------
compatible                string      23.4.0.0

SQL> ALTER DATABASE SET DOWNGRADE COMPATIBILITY TO '23.6.0';

Database altered.

SQL> SHO PARAMETER COMPATIBLE

NAME                      TYPE        VALUE
------------------------- ----------- -------------

compatible                string      23.6.0.0

After dynamically changing the value of COMPATIBLE, be sure to set COMPATIBLE to the new value in the initialization parameter file or server parameter file. Otherwise, an error will occur the next time the database instance is restarted.

Notes:

• Dynamic modification of COMPATIBLE is available only on Oracle AI Database 26ai, and only when changing to a higher COMPATIBLE value within Oracle AI Database 26ai.

• If there are primary and multiple standbys, then you must issue the command on standbys first, and then on the primary.

• If the command is interrupted, then you can issue the change COMPATIBLE command again.

• If the command is issued on the primary database, then it must be issued in an instance where CDB$ROOT is open.

• If multiple sessions issue the same command concurrently, then only one of them will succeed.

• The value of the COMPATIBLE parameter can be increased to a higher version, but it can never be decreased to a lower version.

• When using a standby database, this parameter must have the same value on both the primary and standby databases.

See Also: Oracle AI Database Upgrade Guide for more information on setting this parameter