How is the evolution of BDM handled? Adding or removing columns (fields), renaming, and other operations. I don’t see any documentation on this. Is this done outside of Bonita by accessing the DB directly?
Database DDL on BDM is handled by BonitaBPM platform itself, there’s no need to do manual steps outside of Bonita.
Because of this, DB user that Bonita BPM is using to access BDM database must have sufficient permission to run DDL statement.
Be very careful in using BDM editing…you could cause serious problems…
There is no documentation on the management of BDM’s as such, and as you have found out.
If you use the BDM editor in Studio you should be fine if you DO NOT delete things.
Bonitasoft are aware of the issue and have added changes to BDM into their roadmap as documented here:
http://community.bonitasoft.com/ideas/fix-bdm-so-it-can-merge-items-rather-overwrite-them
Adding fields and queries in general works, Deleting fields could cause everything to stop (for that BDM). Changing Indexes may not work.
You would have to edit all your forms and pages and REST calls as well, make sure you have an Asset index of how and where BDM’s and fields are used. I know this is facility is not in Community. It would be good to have such a report available 
Prior to the changes being made by Bonitasoft be aware that Importing a BDM will overwrite the current one. Completely. So if you have two developers make sure they are using the same BDM, exactly the same BDM.
regards
Seán
PS: If this reply answers your question, please mark a resolved.
Thanks for your answer!
I don’t see this in the docs anywhere.
Can you please point me in the right direction?
How would I go about making schema changes?
In same way as you create new BDM…from Development → Business Data Model → Manage…, you can make any changes, and choose reset BDM database from dialog popup after clicking finish button. But, as Sean McP pointed in his answer, making changes on BDM schema is very critical, and may cause data lose in production database. So you must be very careful on this.
Thanks!
That was very helpful.