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Title
Resync of target database using Oracle Export/Import -
Description
If you do not want to incur any downtime on source database when doing target resync, the preferred approach is to use Oracle hotbackup in conjunction with reconcile command of Shareplex. At times this may not be feasible. For example if source and target have dissimilar OS, then you may be required to use sync procedure such as Oracle Export/Import. But they only work if one has downtime available on source database.
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Cause
General information.
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Resolution
If you are willing to incur a very brief downtime, Oracle export/import can be used conveniently to resync target database while users can keep accessing source database. You will need to provide a very brief downtime lasting a few moments and if that is not at all possible, you will run into out of sync. You can run Oracle Export with the CONSISTENT flag set to 'Y' as follows:
1. Briefly restrict access to the source database.
2. Flush from the Source to the target (i.e. on source at sp_ctrl> flush o.sourcesid)
3. Begin an Export of the Source database with CONSISTENT=Y
4. Allow user access to source database.
5. After the Export is finished on the Source, and after Post stops due to flush on the Target, compare the Source tables to the Target tables to make sure both are the same structure (no DDL changes have occurred).
6. Import the data into the Target database.
7. Disable any triggers or constraints (except PK or U type) on target database.
8. Run cleanup.sql on target database to clean up the Shareplex internal tables that were inherited from source database and can interfere with Post process as well as future activation emanating from secondary to primary.
9. Start post on target.
Another thing that you may have to watch for is the rollback segment issues since you are using the CONSISTENT flag in Export and its occurance depends on the size of the database being exported and the quantum of changes taking place while the Export is in progress. It would be helpful if you had a test environment to test this out.