Hi Konrad Mokrzanski,
Yes, you can create a connection of type JDBC to connect to PostgreSQL database. This connection then can be used as source for mappings/profiles etc. Please note you need to get the TYPE 4 JDBC driver from the database vendor and place the jar in $INFA_HOME/externaljdbcjars directory on the server machine as well as <INFA_CLINET_HOME>\clients\externaljdbcjars folder on the windows machine where Developer Client is installed. If you are using IDQ 10.4.0 version or above, you can use Informatica shipped PostgreSQL JDBC driver.
So, if you are using TYPE 4 JDBC driver provided by the database vendor, you need to know Driver Class Name and JDBC connection URL. In case you are using Informatica provided JDBC driver, use the following information while creating JDBC type connection:
Driver Class Name - com.informatica.jdbc.postgresql.PostgreSQLDriver
JDBC Connection URL - jdbc:informatica:postgresql://<host>:<port>;DatabaseName=<dbname>