RDF/IMP and IMPX System Management Manual (RDF 1.4+)

Online Database Synchronization
HP NonStop RDF/IMP and IMPX System Management Manual—524388-001
7-16
Partial Database Synchronization Issues
There are no special considerations for key-sequenced tables with indexes, but see
below for issues regarding the synchronization of indexes.
SQL Tables With Partitions
The utilities associated with and related to the NonStop SQL product have limitations
that make synchronization of individual partitions complicated and difficult. The
following represent methods that enable you to circumvent these limitations.
1. SQLCI DUP does not have a PARTONLY option. Therefore, you cannot duplicate
only an individual partition.
2. While BACKUP and RESTORE have the PARTONLY option, if you have backed
up tables from the primary system, you must use the MAP NAMES option when
restoring them on the backup system in order to specify the correct system name.
You cannot, however, include both the MAP NAMES and PARTONLY options in
the RESTORE operation. Therefore, because you must use MAP NAMES, you
cannot restore only a single partition.
Described below is a set of steps that can be used to synchronize individual partitions
of NonStop SQL tables (either primary or secondary partitions).
Requirements for Synchronization of Individual Partitions
The following methods work only if all the partitions of a given table still reside on disk
on the backup system. If you do not have all partitions of a given table backed up on
tape and you encounter a total media failure that destroys or renders a volume
inoperable on your backup system, then you might have to synchronize your entire
table.
To prevent this you should take the precaution of having all tables backed up in their
entirety on tape. With the protocol for synchronizing individual tables below, however,
this does not mean you have to back up all tables on your backup system with all
current data. Rather, you can use the following method, which will be very fast and will
enable fast resynchronization should you ever encounter a complete media failure that
requires resynchronization of individual partitions of a table.
1. Rename the table to a temporary name using the SQLCI ALTER TABLE command.
2. Create a duplicate table with the original name of the table you renamed in step 1.
This table must have all the same partitions as the original table.
3. Use BACKUP to put the duplicate table on tape. It will have all the partitions, but
they are empty. Thus, it will not take long to back the partitions up, nor will it take
long to restore any of the partitions.
4. Rename the table to a temporary name and then drop it. By renaming it before
dropping it, you preserve any indexes that are associated with the original table
name.
5. Rename the temporary table (step 1) back to the original table name.