Databases are a type of folder (called a package) that have numerous subfolders containing your document as well as certain files that are useful only to the database. If a database is closed when Time Machine backs it up, then the package is probably copied in its entirety. If not, then the result is less certain. Here is a relevant thread.
I would suggest you do not trash your database until you validate that whatever copy of the database you recover from Time Machine is complete, correct, and has no issues. Archive your older database and set it aside for now.
FWIW, the best way to archive a database is to quit DEVONthink, make an explicit copy of the database with your backup software and make sure that the backups are stored in adequately labeled and dated folders so you know exactly when the database was saved.