SQL/MX 2.x Reference Manual (H06.04+)

SQL/MX Utilities
HP NonStop SQL/MX Reference Manual—540440-003
5-25
Considerations for import
•
It has no droppable primary key, unique key, or foreign key constraints.
•
It has no enabled triggers or you specified the -D option to disable triggers.
To improve the performance of the fast-loading technique, import turns off the audit
attribute for the entire table at the start of the operation and turns it back on when the
operation ends. If another import operation is attempted on the same table while an
import operation with the fast-loading technique is being performed, the second
operation fails with a concurrent access error.
If you turn off auditing for the table, online dumps are invalidated. After the import
operation completes, you must perform a new TMF online dump for all partitions of the
table. When you specify the transaction size using the -T option, transactions are
enforced, and the audit attribute of the table is not altered even if the table meets the
rest of the criteria for using the fast-loading technique.
DDL Locks
When import uses the fast-insert technique, a DDL lock is held on the object for the
entire duration of the operation. This strategy prevents any concurrent import
operation or any DDL or utility operation on this table until the first import using the
fast-insert technique is complete. If you use multiple import processes to load different
partitions of an empty table that meets the described criteria, only the first import
operation would be able to use the more efficient fast-insert technique. Start the
remaining import operations after the first one completes and VSBB inserts will be
used with TMF transactions
If the import operation fails unexpectedly, you must run the RECOVER utility to remove
the DDL lock and perform cleanup. For expected errors, error handling will ensure that
the data in the table is purged.
Recovery
If import fails, you must run the RECOVER utility command to clean up the failed
operation.
•
If import fails to reset the audit attribute of the table that was altered during the
operation, specify RECOVER with the CANCEL or RESUME option to reset the audit
attribute.
•
If import fails after successful data insertion and fails to reset the audit attribute,
specify RECOVER with the RESUME option.
•
If import fails before the data is successfully inserted, specify RECOVER with the
CANCEL option to remove the DDL lock and remove partial data if inserts were not
done.
You can find this information by reading the DDL_LOCK table. If you run the
RECOVER operation with the incorrect option, RECOVER displays an error message
so you can rerun it with the correct option. For details, see Checking File Locks on
page 5-3.