SQL Plan Change After Migration

Hi All,

I did a migration a few months ago from a single instance to RAC database.

The issue that is happening after the migration is the slow query and when I compared between the old environment and new environment, I can see that the execution plan was different for every single query.

In the new environment, obviously the data has been increasing compared to the old one. However, the increment probably still very low as I observed from the number of rows for each table.

I still can go back to check in the old environment from time to time before the old environment is decommissioned.