Is it required to give grants again on existing oracle package after re compiling it?
And also is it mandatory that we need to have db credentials to deploy the packages.
Solution
Grants - once you grant them, they stay. Recompiling doesn't revoke them. If you drop the package manually and THEN re-create it (manually) - then yes, you have to provide grants again.
DB credentials - they are not mandatory IF you run scripts/installations/etc connected as the user, where they are. Some installations are done, connected to DB as SYS, then YES - you have to provide schema/user names with package in order to "put" them in right place.