should we backup & reload data when upgrade to higher version of MongoDB

Question

Recently, I have updated from MongoDB 1.6 to MongoDB 2.0.

I have populated several collections on MongoDB 1.6. After I upgrade to MongoDB 2.0, then start mongodb with the same --dbpath parameter, I found that all previous store collections are still there.

It seems that I don't have to manually backup and reload data into the newer version.

Question> When should we backup & reload data if we decide to upgrade to new version mongodb?

Thank you

Answer 1

You should always backup your data before changing versions - doesn't matter up or down. I'd recommend using mongodump which is super fast (I can tell from my experience, we were able to dump about 15M documents, 12GB database in 2 minutes). Once you've done this, upgrade the binaries and see if the existing data works. If not, restore from the dump using mongorestore.

Answer 2

It#s clearly documented that the database format did not change. So swapping the binaries should be good enough.