how to manage debug and release version on android device?

I'm new to Android dev and I'm almost ready to release a first version of my app :)

While testing the signed release apk on my phone, it refuse to install because the debug version is installed with the debug signature.

So I have to uninstall the debug version but it delete all my database (and it will do it to my friends who are testing it).

Is there a way to manage a debug and a release version of the same app without losing data?

Solution

I'm not aware of any easy way to do get around the uninstall/reinstall process, so your options include...

Buy a second device for testing (some Android devices are very cheap now, especially on eBay)
Use the emulator for testing

I see the same issue, but it's to be expected, so I use the phone for debug dev, and the tablet for production testing. When I'm close to a release, I test the production version on both devices and the emulator.

With your testers, I'd advise that you always give them release versions, but you could include extensive logging to help with problems. Debug versions are then only used by you, and release versions by them. If you provide testers with a release version, they use, and accumulate data, when they come to upgrade to the next version, the data can be retained (or updated, if you change the schema) to migrate their data.

I don't see a need for your testers to be using debug & release versions.