SQL/MX 3.2.1 Reference Manual (H06.26+, J06.15+)

SQL/MX Utilities
HP NonStop SQL/MX Release 3.2.1 Reference Manual—691117-005
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Considerations for import
Considerations for import
Fast Loading and Transaction Considerations
If you are importing into an empty table, import uses the fast-loading technique if the
target table meets these criteria:
•
It is empty.
•
It has no indexes.
•
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.
Import records the status in the DDL_LOCKS metadata table. You can query this table
to determine the progress of import operation.
Status Description
1 The DDL Lock row is created.
2 Audit is turned off as part of import.
3 Data copy completed.