In a previous article about Trigger Parameters we have been using the extension hstore in order to compute some extra field in our records, where the fields used both for the computation and for storing the results were passed in as dynamic parameters. Today we’re going to see another trigger use case for hstore: we are going to record changes made to our tuples.
There was SQL before window functions and SQL after window functions: that’s how powerful this tool is. Being that of a deal breaker unfortunately means that it can be quite hard to grasp the feature. This article aims at making it crystal clear so that you can begin using it today and are able to reason about it and recognize cases where you want to be using window functions.
About the only time when I will accept to work with MySQL is when you need help to migrate away from it because you decided to move to PostgreSQL instead. And it’s already been too much of a pain really, so after all this time I began consolidating what I know about that topic and am writing a software to help me here. Consider it the MySQL Migration Toolkit.
In our recent article about The Most Popular Pub Names we did have a look at how to find the pubs nearby, but didn’t compute the distance in between that pub and us. That’s because how to compute a distance given a position on the earth expressed as longitude and latitude is not that easy. Today, we are going to solve that problem nonetheless, thanks to PostgreSQL Extensions.
In his article titled The Most Popular Pub Names Ross Lawley did show us how to perform some quite interesting geographic queries against MongoDB, using some nice Open Data found at the Open Street Map project.
