While installing Zabbix 3.0 with PostreSQL I found that in documentation https://www.zabbix.com/documentation/3.0/manual/installation/install_from_packages we don`t have part about installing PostgreSQL like we have with MYSQL

Creating initial database

Create zabbix database and user on MySQL. For instructions on doing that, see database creation scripts for MySQL.

Then import initial schema and data.

# cd /usr/share/doc/zabbix-server-mysql-3.0.0
# zcat create.sql.gz | mysql -uroot zabbix

We do have an option for that /usr/share/doc/zabbix-server-pgsql-3.0.3/
and then create.sql

initially this was found on forum https://www.zabbix.com/forum/showthread.php?p=179266