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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?

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  • Watch out, your varchar2 columns may not be wide enough to hold a string converted from we8iso8859p1 to UTF-8.
    – Gerard H. Pille
    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
    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.
    – Gerard H. Pille
    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
    Sep 26, 2020 at 11:02

1 Answer 1

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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 
SYS, ORDSYS, and MDSYS.

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

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