SAND CDBMS Administration Guide
Virtual Mode Operations


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Saving Changes in Virtual Mode
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Updating the Database in Virtual Mode

When updating a database while running in Virtual Mode, use the "master" virtual database instance, with the same name as the real database. Since it is the only virtual instance that can actually make changes to the real database, this instance should generally be made inaccessible to other users. Follow these steps:
  1. Execute the COMMIT [WORK] command to save changes.
  2. SHUTDOWN all other database instances.
  3. Using the SAND CDBMS Interactive SQL utility (nisqlm) connected to the master instance, execute the SHUTDOWN...KEEP CHANGE command (described above) from SQL mode.

Alternatively, the update can be run on all the virtual instances; when the update has completed, users can issue a ROLLBACK [WORK] command to see the changes. Note that in this case the changes will still be lost when an instance is shut down. If this happens, the update will have to be executed again.