Oracle GoldenGate can be a good addition to a lot of upgrade and migration projects to decrease the downtime to a bare minimum, or even zero in some cases.
But before you consider Oracle GoldenGate as THE solution to decrease your downtime you may evaluate if your database is ready for OGG. For this purpose you can download scripts from MyOracle Support (MOS) to check exactly this.
Complete Database Profile OGG readiness check for Classic Extract
This script is intended to query all of the non default database users to identify current configuration and identify any unsupported data types or types that may need special considerations for Oracle GoldenGate in an Oracle environment.
Check OGG readiness for Schema Only
This script is intended to query the database by schema to identify current configuration and identify any unsupported data types or types that may need special considerations for Oracle GoldenGate in an Oracle environment.
Difference and Execution
The main difference between the two scripts is the amount of data being processed. The Schema Script is more targeted and therefore should return fewer items that need additional checking.
Log into sqlplus as sysdba and run the script:
Review the output.