Changing US7ASCII TO WE8ISO8859P1 in 8i, 9i, 10g and 11g (Doc ID 1963942.1)

Last updated on FEBRUARY 18, 2025

Applies to:

Oracle Database Backup Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Oracle Database Cloud Service - Version N/A and later
Oracle Database - Standard Edition - Version 8.1.7.4 to 11.2.0.4 [Release 8.1.7 to 11.2]
Oracle Database - Enterprise Edition - Version 8.1.7.4 to 11.2.0.4 [Release 8.1.7 to 11.2]
Information in this document applies to any platform.

Purpose

To provide a guide to change the NLS_CHARACTERSET from US7ASCII to WE8ISO8859P1

We strongly advice to follow this note also when using export/import from an US7ASCI to a WE8ISO8859P1 database.

The current NLS_CHARACTERSET is seen in NLS_DATABASE_PARAMETERS.

Scope

Any DBA wanting to change the current NLS_CHARACTERSET from US7ASCII to WE8ISO8859P1 in 8i, 9i, 10g and 11g.

Details

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In this Document

1) Prerequisites

US7ASCII versus WE8ISO8859P1

2) Check the source database for:

2.a) Invalid objects.

2.b) Orphaned Datapump primary tables (10g and up)

2.c) Unneeded sample schema's/users.

2.d) Objects in the recyclebin (10g an up)

3) Check if there are no invalid code points in the database for the current NLS_CHARACTERSET:

4) Csscan lists "Lossy" data in the scan performed in step 3.

5) Final Csscan run when going to WE8ISO8859P1

5.a) If there IS NO "Lossy" data in point 3 then perform a last check with csscan :

5.b) If there IS "lossy" data in point 3 and you are sure the "Lossy" data is actual WE8ISO8859P1 data then perform a last check with csscan :

5.c) Both scans will will create 3 files :

5.c.1) The needed csscan output for 8i/9i to use "Alter Database Character Set".

5.c.2) The needed csscan output for 10g and up to use Csalter.

6) Performing the actual character set change:

6.a) For 9i and 8i

6.b) For 10g and up:

7) Make sure clients are using the correct NLS_LANG setting:

7a) Microsoft Windows clients

7b) Unix clients

7c) Other clients:

8) What about Physical / Logical Standby databases?

9) Other Often Asked Questions:

9a) Can I go from WE8ISO8859P1 -> US7ASCII ?

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