Hello,
I regenerated recently the document with the details for Kamailio's database structure, it is available at:
* https://kamailio.org/docs/db-tables/kamailio-db-devel.html
If you haven't read it so far, it is a good source to understand the purpose of the fields needed by kamailio from database.
Contributions to the document are more than appreciated! You can update the xml files from src/lib/srdb1/schema/ and then make a pull request via github.
Cheers, Daniel