The motto of PostgreSQL is widely known: the most advanced open source database in the world. PostgreSQL is a rock-solid, scalable, and safe enterprise-level relational database that is gaining increasing popularity thanks to its wide variety of features and its stability. It is developed and maintained by a team of database experts, but it is open source, which means it is not a commercial product; it belongs to everyone and everyone can contribute to it. Moreover, thanks to its permissive BSD-style license, it can be released as a custom product, allowing both the marketplace and business opportunities to grow.
The latest release of this database is PostgreSQL 11. This version includes a number of new features on both the core side, such as replication and partitioning, and the in-database development side, such as procedures and improved support for event triggers. Developing within PostgreSQL is fun and easy, as it provides a rich infrastructure for developers to integrate the business logic within the database itself. We can implement this logic in a large set of available languages, including Perl, Python, Java, and Ruby, breaking the restriction of having to carry out all database-related activity in SQL.
This book focuses on the development side of interacting with PostgreSQL, which means embedding the code into the database in order to automate tasks, keep data more coherent by enforcing rules, mangling data, and transforming it. Throughout this book, we will look at two "external" languages: Perl and Java. Choosing which external languages to use was not easy, since PostgreSQL supports a large number of them, but the important concept is that, you, the developer, are free to choose the language you prefer in order to implement server-side programming with PostgreSQL. Of course, as you can imagine and as we will see over the course of the book, this does not mean that any language is appropriate for any task. Languages behave differently because they have different sets of features, different cultures, different ecosystems and libraries, and different support for different tools. Therefore, even though PostgreSQL allows us freedom with regard to the language we use, it is important that we bear in mind that different situations might require different languages.
PostgreSQL supports a lot of foreign languages, which can be either scripting languages or not. As you can imagine, explaining all the details of every language is outside the scope of this book. However, in order to demonstrate the differences between the native PostgreSQL language (which is often called PL/pgSQL) and foreign languages, we chose to show a well-integrated scripting language, Perl, and a compiled one, Java. The same concepts, advantages, and drawbacks of these two languages can be applied to other languages.
Some examples will be implemented using the C language, which is the language that PostgreSQL itself is implemented in. For this reason, it has better support in PostgreSQL. However, it is possible to almost totally avoid developing in the C language and to opt instead for friendlier and easier languages.
In this chapter, we will take a look at the following topics:
- What server-side programming is
- An introduction to the languages that will be used in the rest of the book to implement examples
- How the book is organized and which topics will be covered in each chapter
- How to read and understand the code examples
