Explanation:
While performing an export of multiple tables having referential integrity constraints and while the database is open for user access, you must specify the CONSISTENT=Y parameter. This parameter enables a read-consistent view of the data for multiple tables. If you specify CONSISTENT=N, each table is exported in separate transactions, which might lead to inconsistency of two or more tables that have referential integrity constraints enabled.
Reference:
Oracle 9i Net Services Administrator’s Guide
Oracle 9i Net Services Reference Guide
Oracle 9i Recovery Manager Reference
Oracle 9i Backup and Recovery Concepts

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