Admin/B&R

Consistent export not possible as SYS/SYSDBA user!

Qhtlr 2007. 8. 17. 08:59
When performing a consistent export (i.e. setting CONSISTENT=Y), do not use the SYS user, or connect as SYSDBA. If you do, there is no guarentee from Oracle that the exported data will be consistent.

When you perform a consistent export, Oracle issues the statement 'SET TRANSACTION READ ONLY' (see utilities manual on consistent parmaeter for export).

Setting a transaction to READ ONLY does not work for the SYS user. (See Oracle SQL Reference on SET TRANSACTION command). Quote from Oracle documentation below.
--------
This clause is not supported for the user SYS. That is, queries by SYS will return changes made during the transaction even if SYS has set the transaction to be READ ONLY.
--------

One of the symptons of an inconsistent export is ORA-2298.

For those of you that rely on this as a backup tool, you should change to the SYSTEM user for performing exports.