I need create a copy of an Oracle 12.2 instance (Oracle Restart) running on an Linux VM. The new instance needs a charset conversion from WE8ISO8859P1 to UTF8

I started by creating a clone of the VM that is now up and running.

I was thinking about following these steps:

  1. expdp FULL=YES from the cloned machine to a safe storage location
  2. destroy the database from the clone using DBCA
  3. create a new database on the clone using DBCA setting UTF-8 as charset
  4. impdp FULL=YES from the previous exported datapump

I have some doubts about the impdp FULL=YES... will this work or will it overwite some configuration on SYS or other Oracle maintained schemas with some values that still refers to WE8ISO8859P1 charset?

Will this work or should I exclude all the Oracle maintained schemas from the impdp?

  • Watch out, your varchar2 columns may not be wide enough to hold a string converted from we8iso8859p1 to UTF-8. Commented Mar 19, 2020 at 20:59
  • Sure, the character length semantic is a topic I do know very well ad I already modified on the source database on both objects definition and PL/SQL code variable declaration
    – Max
    Commented Mar 20, 2020 at 10:08
  • OK, couldn't tell from your profile what your experience was. Hope you are in good health, better than your avatar. Commented Mar 20, 2020 at 10:59
  • Keep in mind that conversion from Latin-1 (1-byte charset) to UTF-8 (multi-byte charset) has effects on "varchar length". For example, a varchar2 column at max size full with umlauts would no longer fit into your UTF8 column of the same size. See my article here on details; note that with 12c you can take advantage of "extended varchar2" with 32k size, so you won't need the CLOB work-around described (i couldn't do that on 9i more than 10 years ago).
    – Izzy
    Commented Sep 26, 2020 at 11:02

1 Answer 1


On export the documentation states:

A full export does not, by default, export system schemas that contain Oracle-managed data 
and metadata. Examples of system schemas that are not exported by default include 

If you want to be absolutely sure I would switch to a schema-mode import instead. You can still use the full export. That way you specify what schemas you want to import.

Regards, Daniel

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.