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

SQL/MX Statements
HP NonStop SQL/MX Release 3.2.1 Reference Manual—691117-005
2-197
Considerations for DUP
Considerations for DUP
•
Referential integrity constraints and triggers are ignored.
•
The source table can exist on a remote node and be referenced by the current
DUP operation if the remote node is visible to the local node. The target table can
also exist in a catalog and schema that reside on a visible remote node.
•
DUP does not check disk space before running the request. You must confirm that
enough disk space is available before running the DUP request.
•
DUP displays errors if the source table or target table and its dependent indexes
cannot be accessed, or if the load fails in response to a resource or file system
problem.
You must run the RECOVER utility to clean up a failed DUP operation. If the DUP
operation fails after all of the data is successfully copied to the target objects,
specify RECOVER with the RESUME option to complete the DUP operation. If the
DUP operation fails before the data is successfully copied, specify RECOVER with
the CANCEL option to roll back the DUP operation. This status can be found by
reading the DDL_LOCKS definition schema table in the source table’s catalog. 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 DDL Locks on page 2-9.
No restart facility is available to handle partially copied data.
•
During the DUP operation, the target table is marked as corrupt to prevent other
processes from viewing the data until the operation completes successfully.
°
All utility operations have the potential to run for hours, especially those that
involve a great deal of data movement. To manage systems effectively, you
need to know how far the operation has proceeded and how much longer it
needs to run. Utilities provide progress reports that indicate what step is in
progress. Utility operations periodically place progress reports in the metadata
tables through the DDL lock mechanism. You can examine the metadata to get
the latest information. These reports are referred to as the operation's
progress. The DUP operation has the option to log these progress reports to
an OSS text file. DDL locks
Many utility operations run in multiple TMF transactions. As a result, conflicting
operations that change metadata and label information affecting the outcome
of the utility are executed concurrently.
To serialize these utility operations, NonStop SQL/MX has the concept of a
DDL lock. This is a lock that prevents database structure changes from
occurring while a utility request is executing. A utility request informs SQL that
it is running, perform commands in as many transactions as necessary, then
informs SQL that the operation has completed. While the utility request is
running, no conflicting DDL or utility operation can occur. That is, you can
make no database structural change that would affect the utility.