COMPATIBLE
Oracle recommends that you only raise the COMPATIBLE parameter after you have thoroughly tested the upgraded database.
After you increase the COMPATIBLE parameter, you cannot downgrade the database.
You can only set it to a higher value. Once changed, you are not able to revert to the previous value.
Check
SELECT name, value
FROM v$parameter
WHERE name = 'compatible'
Update COMPATIBLE
When upgrading an Oracle database, leave COMPATIBLE set at the previous version until you are sure there is no need to downgrade.Change the value to allow use of new features.Once changed, and the database has been opened, it is not possible to revert to a lower value for COMPATIBLE.
Examples for different Oracle versions
Generally, only the first three digits of an Oracle version are relevant for the COMPATIBLE parameter.
(On rare occasions a feature may require the 4th digit; but you should assume not unless you see specific instructions from Oracle to use it).Some examples for different Oracle versions....
ALTER SYSTEM SET COMPATIBLE = '11.2.0' SCOPE=SPFILE;
ALTER SYSTEM SET COMPATIBLE = '12.1.0' SCOPE=SPFILE;
ALTER SYSTEM SET COMPATIBLE = '12.2.0' SCOPE=SPFILE;
Bounce Database
The database must be restarted for the change to take effect.
shutdown immediate
startup
Bibliography
https://mikedietrichde.com/2019/04/17/when-and-how-should-you-change-compatible/ https://docs.oracle.com/en/database/oracle/oracle-database/12.2/upgrd/what-is-oracle-database-compatibility.htmlhttps://docs.oracle.com/en/database/oracle/oracle-database/19/upgrd/what-is-oracle-database-compatibility.html
https://support.oracle.comHow To Change The COMPATIBLE Parameter And What Is The Significance? (Doc ID 733987.1)