I've installed NFA 9.3.3 and would like to import data from my old NetQOS v9.0.
I was looking fot mysql database structure and it appears to be compatible.
Is there a way to do it securely?
This would not be supported. The database structures/functions differ quite a bit between 9.0 and 9.3 and the only method to bring 9.0 data up to 9.3.3 would be via the upgrade process.