Foreword

As children, we were all told at one time or another that “we are what we eat,” as a reminder that our diet is integral to our health and quality of life. In the modern world, with location-aware smartphones in our pockets, GPS units in our vehicles, and the internet addresses of our computers geocoded, it has also become true that “who we are is where we are”—every individual is now a mobile sensor, generating a ceaseless flow of location-encoded data as they move about the planet.

To manage and tame that flow of data, and the parallel flow of data opened up by economical satellite imaging and crowd-sourced mapping, we need tools equal to the task—tools that can persistently store the data, efficiently access it, and powerfully analyze it. We need spatial databases, like PostGIS.

Prior to the advent of spatial databases, computer analysis of location and mapping data was done with geographic information systems (GIS) running on desktop workstations. When it was first released in 2001, the project name was just a simple play on words—naturally a spatial extension of the PostgreSQL database would be named PostGIS.

But the name has come to have further significance as the project has matured.

Each year, new functions have been added for data analysis, and each year users have pressed those functions further and further, doing the kinds of work that in earlier years would have required a specialized GIS workstation. PostGIS is actually creating a world that is post-GIS—we don’t need GIS software to do GIS work anymore; a spatial database suffices.

In March of 2002, not even one year after the first release of PostGIS, I asked on the user mailing list for examples of how people were using PostGIS. And in her first post to the list, Regina Obe answered this way:

We use it here [city of Boston] for proximity analysis. Part of our department is in charge of distributing foreclosed property to developers, etc., to build houses, businesses, etc. We use PostGIS to list properties by proximity ... so that if a developer wants to develop on a piece of land that is, say, X in size, they will be able to get a better sense of whether it can be done.

Even at that early date in the project, Regina was already testing the capabilities of PostGIS and creating clever analyses.

In the years that followed, in over 1,000 posts to the PostGIS mailing lists, Regina and her husband, Leo Hsu, have become leaders of the PostGIS community, providing assistance to new users and constantly pushing the boundaries of what is possible. On the strength of her contributions to the project documentation and quality control processes, Regina joined the Project Steering Committee in 2008 and has continued to contribute to the development of the software and reference documentation.

Making the most of a spatial database requires going beyond simple storage and retrieval (though PostGIS in Action provides great introductory material to get you started). Once you’ve mastered the basics, you can dive right into the advanced material and learn how to analyze your data. Location is the universal key; it allows you to join and analyze data sets in ways that are impossible using conventional approaches.

Enjoy this book and enjoy the insights it provides in putting location data to work. Regina and Leo have distilled a huge body of information into a concise guide that’s truly one of a kind.

PAUL RAMSEY
CHAIR, POSTGIS
PROJECT STEERING COMMITTEE