There are now multiple backend storage modules available for storing user's bayesian data. As such you might want to migrate from one backend to another. Here is a simple procedure for migrating from one backend to another.
Note that if you have individual user databases you will have to perform a similar procedure for each one of them.
1) sa-learn --sync (this will sync any outstanding journal entries)
2) sa-learn --backup > backup.txt
3) sa-learn --clear (this is optional, but good to do to clear out the old database)
At this point, if you have multiple databases, you should perform the procedure above for each of them.
4) Once you have backed up all databases you can update your configuration for the new database backend. This will involve at least the bayes_store_module config option and may involve some additional config options depending on what is required by the module.
5) For each backed up database run: sa-learn --restore backup.txt
If you are migrating to SQL you can make use of the -u <username> option in sa-learn to populate each user's database. Otherwise, you must run sa-learn as the user who database you are restoring.