※This sample exam is different from those that appear in the actual OSS-DB Exam.
Open source software has common features such as source code available, redistributable. However, there are several kinds of licenses, and conditions of source modification and redistribution are different. For this reason, you need to be careful as to what kind of license the software you use is.
The license of PostgreSQL is based on the BSD license, there is no obligation to disclose the code when the source is modified, and it can also be used commercially.