20 Pre Upgrade Checklist for Migrating Oracle Database to New version

Taking appropriate steps prior to major oracle database upgrades helps to prevent any warning , slowness during or after migration to new oracle database version ..

Following 20 steps will cover most of the pre-upgrade checklist that can be followed for smooth upgrades ..

1. System/Sysaux/Undo tablespace adequate free space avoids errors during migration script execution , at least 1-2 GB free space to be maintained.

2. Invalid Objects in source database to be validated or removed in case not required to avoid conflicts later 



3. DB link dependency to be identified , all db links to be listed with their dependency on remote system (user , credentials , TNS name) used by materialized views in order to configure/verify on destination db



4. External Table dependency to be identified , source file directory location on file system such as NFS /ASM /ACFS to be resolved on destination



5. System/Custom triggers to be validated , system triggers such as pdb open , on startup , login triggers are very dangerous if remains invalid 



6. Upgrade version compatibility for your source database in order to check if middle version upgrade is required or direct path is supported.



7. patch level pre-requisites to be fulfilled as per required minimum requirements prior upgrade 



8. on off/bug patches applied on source and its availability on new version to be verified to avoid re-occurrence of issue on new version.




9. De-fragmentation of indexes/Tables at source to reduce the size of the db which improves the time taken during restore , can be ignored in case of import/export which automatically rebuilds the index/tables during import.




10. TNS names file with appropriate resolvable tns entries at destination . in order to work upon firewall port opening at early stages.



11. Backup utility linking binary dependency with media manager software to support RMAN backup storage on external media



12. Monitoring cron or OEM verification to ensure all monitoring metrics are getting migrated along with SMTP for mailx notification at destination server to receive important alerts.

13. backup/flashback checks before upgrade to enable flashback restore point as a rollback strategy and plan sufficient disk space.

14. DG broker , golden gate related verification including config file consistency to avoid wrong configuration at destination leading to out of sync scenario.

15. Recyclebin purge / restore to free up the unwanted db space or restore the tables needed for future



16. Data Purging / Archival to reduce the volume of the data with scope of de-fragmentation 

17. registry$history check for invalid components and fix them prior upgrade script run to avoid conflicts.

18. System requirements such as minimum kernal level , parameter , shared memory ,  /temp space availability , swap space, disk permissions etc



19. Archival log disable with large redo log group member size to reduce log switch wait during migration script execution


20. Tables stats backup as a safe approach to tackle known performance issue, also to identify major SQL's performance history and keep the needful fixes proactively in the plan.

All above checks are starting point to plan your database upgrade on correct direction , additional checks to be includes as per your setup or previous experience with the application / database..