Rebuilding a database is a specific type of import and export involving unloading and reloading your entire database. The rebuild (unload/load) and extract procedures are used to rebuild databases, to create new databases from part of an existing one, and to eliminate unused free pages.
If you are rebuilding your database to upgrade it to a newer version of SQL Anywhere, see Upgrading SQL Anywhere.
You can rebuild your database from Sybase Central or by using the dbunload utility.
It is good practice to make backups of your database before rebuilding, especially if you choose to replace the original database with the rebuilt database.
For more information, see Backup and data recovery.
With importing and exporting, the destination of the data is either into your database or out of your database. Importing reads data into your database. Exporting writes data out of your database. Often the information is either coming from or going to another non-SQL Anywhere database.
If you specify the encryption options -ek, -ep, or -et, the LOAD TABLE statements in the reload.sql file must include the encryption key. Hard-coding the key compromises security, so a parameter in the reload.sql file specifies the encryption key. When you execute the reload.sql file with Interactive SQL, you must specify the encryption key as a parameter. If you do not specify the key in the READ statement, Interactive SQL prompts for the key. See Interactive SQL utility (dbisql).
Loading and unloading takes data and schema out of a SQL Anywhere database and then places the data and schema back into a SQL Anywhere database. The unloading procedure produces data files and a reload.sql file which contains table definitions required to recreate the table exactly. Running the reload.sql script recreates the tables and loads the data back into them.
Rebuilding a database can be a time-consuming operation, and can require a large amount of disk space. As well, the database is unavailable for use while being unloaded and reloaded. For these reasons, rebuilding a database is not advised in a production environment unless you have a definite goal in mind.
Reasons to rebuild databases
Rebuild databases not involved in synchronization or replication
Rebuild databases involved in synchronization or replication
Using the dbunload utility to rebuild databases
Using the UNLOAD TABLE statement to rebuild databases
Export table data or table schema
Reload a database
Minimize downtime when rebuilding a database
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