Is it possible to install openfire with postgresql database but schema different than public ?
I do not believe so. There is probably a way to hack the JDBC connector to set a non-public default schema, but I do not know how.
It’s possible. public schema is default search_path. You can set default seach_path for each pg users.
If your Openfire PG username is example openfireadm then
ALTER ROLE openfireadm SET search_path=someschema;
After that run install openfire_postgresql.sql