Home/ Questions/Q 69011
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-10T19:30:23+00:00

I have 2 databases, and I want to transport an existing table containing a

  • 0

I have 2 databases, and I want to transport an existing table containing a CHAR column from database A to database B.

Database A is Oracle 9i, has encoding WE8ISO8859P1, and contains a table ‘foo’ with at least 1 column of type CHAR(1 char). I can not change the table on database A because it is part of a third party setup.

Database B is my own Oracle 10g database, using encoding AL32UTF8 for all kinds of reasons, and I want to copy foo into this database.

I setup a database link from database B to database A. Then I issue the following command:

*create table bar as select * from #link#.foo;*

The data gets copied over nicely, but when I check the types of the columns, I notice that CHAR(1 char) has been converted into CHAR(3 char), and when querying the data in database B, it is all padded with spaces.

I think somewhere underwater, Oracle confuses it’s own bytes and chars. CHAR(1 byte) is different from CHAR(1 char) etc. I’ve read about all that.

Why does the datatype change into a padded CHAR(3 char) and how do I stop Oracle from doing this?

Edit: It seems to have to do with transfering CHAR’s between two specific patchlevels of Oracle 9 and 10. It looks like it is really a bug. as soon as I find out I’ll post an update. Meanwhile: don’t try to move CHAR’s between databases like I described. VARCHAR2 works fine (tested).

Edit 2: I found the answer and posted it here: Why does Char(1) change to Char(3) when copying over an Oracle DBLINK? Too bad I can not accept my own answer, because my problem is solved.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. This problem is caused by the way Oracle (mis)handles character conversions between different character sets based on the original column length definition. When you define the size of a character type column in bytes, Oracle does not know how to do a conversion and bodges it. The solution is to always define the length of a character type in characters.

    For a more in-depth explanation of the problem and how I figured this out have a look at http://www.rolfje.com/2008/11/04/transporting-oracle-chars-over-a-dblink/

    • 0