DSpace downgrade

[Monica Vimbai Chatikobo]

I would like to know the implications or steps particularly regarding downgrading DSpace

I installed DSpace 8 on a test server and would like to downgrade it to v7.6.3. Are there any implications particularly regarding the database downgrade or mapping

Regards

[DSpace Community]

Hi,

DSpace doesn't have a process to "downgrade" installations.  This process is not always easy because it does require manually downgrading the database.

Since this is a test server, if you don't care able the test data, then the easiest approach would be to destroy (drop) the existing database & delete the DSpace 8 installation (warning: This will destroy all your test data). Then, install DSpace 7.6.3 following the Installation instructions: https://wiki.lyrasis.org/display/DSDOC7x/Installing+DSpace

If you want to keep your test data, then you'd still need to delete the DSpace 8 installation.  But, instead of destroying the existing database, you'd have to manually *downgrade* the database to be compatible with DSpace 7.x.  The way you would do that is to *undo* any database migrations that begin with "V8.0_" (as these were all executed to bring your database to 8.0 compliance).  Those migrations can be found here: https://github.com/DSpace/DSpace/tree/dspace-8_x/dspace-api/src/main/resources/org/dspace/storage/rdbms/sqlmigration/postgres

Unfortunately, there's no script or automated way to undo database migrations. You would literally have to read the migration and figure out how to undo the changes that it made. Therefore, before doing anything, I'd highly recommend backing up your database (in case you make a mistake).  In the case of DSpace 7.6.x->8.0, it looks like the two "V8.0_" migrations just created some new database tables, indexes and sequences. So, if you dropped these, then it should return your database to 7.6.x compliance.

Finally, I should note that this a scenario where it is useful to create regular database backups.  For example, if you had  backup from DSpace 7.6.x (e.g. from before upgrading to 8.0), then that backup could be used to more easily revert to DSpace 7.6.3 by just installing a fresh copy of DSpace 7.6.3 with that database backup, similar to the "Migrating DSpace to a new server" instructions: https://wiki.lyrasis.org/display/DSDOC7x/Migrating+DSpace+to+a+new+server

Tim

[Job Diogenes Ribeiro Borges]

A way to achieve these, could be export and import to a old version.