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Managing common user in oracle 12c

N_Raj
N_Raj Member Posts: 606 Bronze Badge
edited May 31, 2017 4:26AM in Multitenant

Hi All,

I am learning Oracle 12.2C database concepts. I read about  common user creations. i have doubts.Please anyone clear it.

1,What is the usage of common user?Where will  user object create whether pdb or cdb db?

2,How to kill a particular common user session? For ex : If user is connecting from one of the pdb,how to kill that session,whether i have to go  a particular pdb then kill or i can do it from cdb?

3,when unplug pdb from cdb ,plug to another cdb?when happens for the common user?

4,Is it possible to prevent/lock some pdb's to use common user?

Thanks & Regards,

John ThortonEmad Al-Mousa

Best Answer

  • Franck Pachot
    Franck Pachot Member Posts: 912 Bronze Trophy
    edited May 17, 2017 3:18PM Answer ✓

    Hi,

    >> What is the usage of common user?

    a user created at CDB level and known by all containers: CDB$ROOT and the PDBs. You use them for the CDB administrator, for CDB monitoring, etc.

    >> Where will  user object create whether pdb or cdb db?

    a common user may have a schema in each container. But in practice, the common user will probably not own any objects

    >> 2,How to kill a particular common user session?

    just kill it from where you can see it. When in CDB$ROOT you see all sessions. When in PDB you see session on this PDB.

    >> 3,when unplug pdb from cdb ,plug to another cdb?when happens for the common user?

    problems may happen here when a PDB with a common user is plugged to a PDB without it. An example here: https://laurent-leturgez.com/2016/03/08/when-an-oracle-12c-common-user-transforms-himself-as-a-local-user-but-keeps-his-…

    This is the good reason to have a different prefix (the C##)

    >> 4,Is it possible to prevent/lock some pdb's to use common user?

    Yes you can revoke the set container and create session

    Think of common user as system administrators, and local user as application owners/users

    Regards,

    Franck

    N_RajEmad Al-Mousa

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