51 
An Interview with Craig Kerstiens
Craig heads up the Cloud team at @citusdata. Citus extends Postgres to be a horizontally scalable distributed database. If you have a database, especially Postgres, that needs to scale beyond a single node (typically at 100GB and up) Craig is always happy to chat and see if Citus can help.
Previously Craig has spent a number of years @heroku, a platform-as-a-service, which takes much of the overhead out of IT and lets developers focus on building features and adding value. The bulk of Craig’s time at Heroku was spent running product and marketing for Heroku Data.
In your opinion, how important are extensions for the PostgreSQL open source project and ecosystem?
To me the extension APIs and growing ecosystem of extensions are the bi est advancement to Postgr in probably the last 10 years. Extensions have allowed Postgr to extend beyond a traditional relational database to much more of a data platform. Whether it’s the initial NoSQL datatyp (if we exclude XML that ) in hstore, to the rich feature set in geospatial with GIS, or approximation al-
gorithms such |
HyperLogLog or TopN you have extensions that |
now by themselv |
take Postgr into a new frontier. |
Extensions allow the core to move at a slower pace, which mak sense. Each new feature in core means it h to be thoroughly tested and safe. That’s not to say that extensions don’t, but extensions that can exist outside core, then become part of the contrib provide
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never search for HyperLogLog, but a search for Postgr approximate count or approximate distincts would yield it pretty quickly.
Is there any downside you could think of when your application code base now relies on some PostgreSQL extension to run? I could think of extension’s availability in cloud and SaaS o ferings, for instance.
It really depends. There are extensions that are much more bleeding edge, and on that are more mature. Many of the major cloud providers support a range of extensions, but they won’t support any extension. If they do support it there isn’t a big downside to leveraging it. If they don’t you need to weigh the cost of running and managing Postgr yourself vs. how much value that particular extension would provide. As with all things managed vs. not, there a trade-off there and you need to decide which one right for you.
Though if something supported and easy to leverage wherever you run, by all means, go for it.
Part IX
Closing Thoughts
I have written The Art Of PostgreSQL so that as a developer, you may think of SQL as a full-blown programming language. Some of the problems that we have to solve as developers are best addressed using SQL.
Not just any SQL will do: PostgreSQL the world’s most advanced open source database. I like to say that PostgreSQL YeSQL as a pun, which compares it favorably to many NoSQL solutions out there. PostgreSQL delivers the whole SQL experience with advanced data processing functionality and document-based approaches.
We have seen many SQL features — I hope many you didn’t know before. Now you can follow the one resultset, one query mantra, and maintain your queries over the entirety of their life cycles: from speci cation to testing, including code review and rewrite.
Of course your journey into The Art Of PostgreSQL is only starting. Writing code is fun. Have fun writing SQL!
Knowledge of no value unless you put it into practice.
— Anton Chekhov
