In DTP for macOS I have a database I want to aces from two different users on the same machine.
The two users will never work on the database at the same time, but they might have the database open at the same time. I can see two ways to manage this:
The simple solution: One database under a commonly accessible path.
or
The save solution: Two separate databases in each user’s area synced via an external sync store?
Solution 1 is obviously a lot slimmer and solution 2 to has quite a bit of overhead with the external sync store, but it might be saver…
This situation comes up on the forum regularly – so you might be able to find other advice on it.
DEVONthink aside, two users on the same Mac at the same time would be best accomplished by macOS “fast user switching”, which I assume is what you’re doing. (BTW, this is never really “at the same time”.)
If your databases are in the Shared folder under Users (e.g. Macintosh HD > Users > Shared – or whatever your volume name is), then the users could launch DEVONthink and access a database. For safety, you should have each user close the database before they log out and the other user logs in. The second user would then open the database, use it, then close it and log out. And so forth.
Two accounts on the same machine cannot open the same database, regardless if they’re “working on it” or not.
Unless, as korm suggested, you close the database before switching Users, the accounts should be treated as separate machines and have their own copy of the database.
You can create a sync store in the system Shared folder on your boot volume and sync with it – as Jim advised, each user has its own instance of the database located in its own Documents folder (or wherever) and syncs with the sync store you placed in Shared
Be sure to test this first, before committing to the process with your beloved data.