In this section, we will introduce PostgreSQL, which is a mature relational database engine that started as a research project at University of California in mid-1980s and surfaced as a community open source project with a permissive license (similar with a BSD license) in 1995.

In 2014, PostgreSQL 9.4 was released and introduced a new binary JSON (JSONB) data type support alongside its existing JSON data type support. This allows for more efficient storage and for better performance through JSONB indexing capabilities.

Another feature that makes it interesting for us is that it supports JavaScript as a procedural language through the PL/v8 project. A procedural language can be used to create user-defined functions and PostgreSQL alongside SQL and C has built-in support for procedural languages such as Python, Perl, and Tcl through PL/Python, PL/Perl, and PL/Tcl. Many other procedural languages are supported through community contributions and PL/v8 is one...