Backup and restore

As part of the incremental Backup work for the OU, I did some work on a new method for restoring courses.

Currently, when restoring a course backup, we can "Restore to a new Course", "Restore to an existing course, Adding data to it" or "Restore to an existing Course, deleting all data first"

For the Incremental Backups, we needed an option that Restores to an existing course, updating the data.

To do this, it uses a new table called "backup_guids" and each row in a module table  gets assigned a sha1 – for example, a forum course module gets a GUID/Sha1 based on the site identifier, the module type(forum), the id from the course modules table, and the instance of the module(which will generate a unique identifier for the record), forums also get GUIDS for Discussions and Posts so they can all be updated. - this "GUID" is also stored in the backup file like this:
<MOD>
<GUID>fd6d7a3001806017859a7b4268117fca72c0f0b1</GUID>
<ID>20</ID>
<TYPE>forum</TYPE>

or:
<DISCUSSION>
<GUID>b287d1bc19d819285130d7ca5032d78f1bb0b40a</GUID>
<ID>7</ID>
<NAME>test news 1</NAME>

or:
<POST>
<GUID>7fe51117317b46d92263264c537e144443437e0e</GUID>
<ID>10</ID><POST>

so when this is restored - it checks the GUID in the restore file against the GUIDS in the backup_guids table for this course, and if they're the same - it updates the existing object without duplicating data.

This could have some interesting use-case's such as the ability to update a course previously downloaded from a learning repository - for example someone could have a modified version of the demo course from demo.moodle.org with some extra stuff added. They could update their local course and get the new stuff from the demo course, without deleting any of their own additions or duplicating data.

I'd quite like to get this into Moodle 2.0 - any feedback?

Thanks!

:-)

Dan