Restoring the database dump of a newer version to an older version of mongodb

Question

I find myself having to move a database between hosts but at the moment don't have the option of upgrading or downgrading any of the hosts.

I'm trying to find out if it is safe to do the following:

I have a running mongodb 3.0.15 instance which I've taken a dump from. I've restored that to another mongo instance running version 3.4.4 without any issues.

Can I now take a dump of the data in 3.4.4 and restore it on 3.0.15? There has been no material change to the db besides the usual create/update & deletion of records while running on the surrogate host.

Answer 1

Assuming you aren't using any newer features or index/collection options from MongoDB 3.2+ that aren't supported in MongoDB 3.0, you should be able to restore the backup.

Before doing so, I would review the downgrade instructions in the MongoDB documentation to check for potential issues:

• Downgrade MongoDB 3.4 to 3.2
• Downgrade MongoDB from 3.2

The downgrade instructions assume a change of binaries rather than a mongodump backup, but the caveats on backward-incompatible features such as newer index and collection options still apply.

I suggest using the 3.4 versions of mongodump and mongorestore to test your outcome in a development or staging environment before applying to a production deployment.