Is it possible to use postgresql with icingadb?

Hello
You can use it
https://icinga.com/docs/icinga-db/latest/doc/02-Installation/03-Debian/#setting-up-a-postgresql-database
or with ido
https://icinga.com/docs/icinga-2/2.10/doc/02-getting-started/#configuring-db-ido-postgresql

but for x509 module I’ve got an issue

You can give a try if you want for a basic usage it will be fine