Hi Serban,
You may or may not be on the right track, because based on that email message your usage of terminology is not always clear.
Consider these three concepts:
- Database server (a server running PostgreSQL or MySql)
- A database (one server can host multiple databases)
- A table (one database contains many tables)
When you wrote "And all 3 tables" you probably meant "all 3 apps"? When you wrote "pointing to the same database" you probably meant "pointing to (multiple) databases on the same database server instance"?
All the apps (hyperkitty, postorius, core) could share the same database server, as long as they have their own database. Rather, one DB for core, another DB for web. So, two databases. Potentially on the same hardware instance.
The new hyperkitty archives are usually stored in the database and not "FS local" (filesystem local).
Next, this part "core+web (instance 1) and Hyperkitty (instance 2)." The main division is between Web (postorius, hyperkitty) and Core (mailman3-core). In other words, Hyperkitty is part of the web component. Postorius + Hyperkitty make up the web layer. So you wouldn't usually split up web and hyperkitty separately.