Quote Originally Posted by rtnataraj View Post
Changing the Database Character Set of an Existing Database

Database character set migration has two stages:

1. Data scanning -- can identify number of schema objects where the column widths need to be expanded and the extent of the data that does not exist in the target character repertoire (range). This information helps to determine the best approach for converting the database character set.

2. Data conversion -- ensure if the database does not contain any of the inconsistencies described in "Character Set Conversion Issues"


Also refer.
Doc ID: 261871.1 Changing EL8ISO8859P7 to EL8MSWIN1253
Are you really suggesting to change Database character set to solve an export issue?

Please don't!

Do this...

export NLS_LANG=EL8ISO8859P7
run your export