Level up your PostgreSQL Skill with Lateral Joins

PostgreSQL’s lateral joins have a lot of uses. One of my favorites is the ability to reuse calculations in a query. Before I discovered lateral joins, I would either copy calculations throughout the query or use subqueries. Neither of these approaches is ideal because they make the query much more difficult to read—and nearly impossible […]

A Case for Learning J

There are few things as humbling as learning a programming language of a radically different paradigm from any you’ve used before. Recently, I’ve been feeling a need to learn a language with which I could easily manipulate data – usually collections of numbers. I thought about learning R or Julia, but while I’m sure those […]

Using ActiveRecord to Abstract “Greatest N Per Group” Queries

Some database-related projects require access to information based around maximum and minimum values. Recently, I was trying to figure out the best way to perform a “greatest N per group” query in an ActiveRecord model with a SQL database backend. Eventually, I settled on the SQL proposed by Bill Karwin on StackOverflow. Once I had […]