Rebuilding a database consists of unloading and reloading the database to upgrade its file format. When you upgrade the file format, it changes the format used to store and access data on disk, letting you use all the new features and performance enhancements in the latest version of the software.
Unloading and reloading a large database can be time consuming and can require a large amount of disk space. The process may require disk space approximately twice the size of your database to hold the unloaded data and the new database file.
If you are rebuilding a database that is a remote database in a MobiLink installation or that is involved in SQL Remote replication, and if you use the dbunload utility, you must be sure to use the -ar or -an option. These options ensure that the transaction log offsets for the new database are set to match those of the old database.
When using dbunload with a version 10 or later database, the version of dbunload used must match the version of the database server used to access the database. If an older version of dbunload is used with a newer database server, or vice versa, an error is returned.
Because of index changes in SQL Anywhere, when you rebuild a database by unloading and reloading it, the rebuilt database may be smaller than the original database. This decrease in database size does not indicate a problem or a loss of data.
It is recommended that you back up your database before you rebuild it.
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