character set confusion

Hello all,

What are the limitations of materialized views across character sets? We will be upgrading the source database for many, many materialized views to Oracle 10.2.0.2 in a few months. We will also be converting the database to UTF8 although that will probably occur a few months later. The target database is, at the moment, 9.2.0.8 and USASCII7. It too will be upgraded eventually but I need to determine if there is a reason to perform the upgrade simultaneously with the upgrade and/or the UTF8 conversion. Both databases have been around for many years; about a third of the objects in question still use the SNAP$ convention.

It seems logical to me that there would be the potential for the target to be unable to hold some of the data stored in the UTF8 source database, but every test I've run has worked. I did manage to hit the bug with the big endian/little endian issue but once that patch was in, no problems. I've opened a case with Oracle, but their answer was brief and not very reassuring. Supposedly, if I upgrade both databases to 10g, I won't have to worry about any differences in character sets. Somehow, that's not making sense to me and no logic was offered with the answer.

So is there some kind of conversion that occurs in the materialized view process? Or would I eventually hit some bit of data that could not be stored in the target database if it remains USASCII7? Would it make more sense to convert both to UTF8? I've got time to plan for this and I'd like to do it right, short of having to convert to completely new form of replication overnight.

Suggestions appreciated, including any test cases that might conclusively prove the possibility of failure. I'd rather find out now than at 3:00 am on Feb 23rd 2009.

tia ... Robyn

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