Posts

Functions are great. Having cut my teeth on a database that didn’t even provide the ability to define functions, I’ve come to almost take them for granted in Postgres (PostgreSQL). However, with this kind of ubiquity, sometimes they can be overused in ways that don’t seem to be part of the common programmer lexicon. In this week’s PG Phriday series on performance-killing missteps, I’m going to talk a bit about set theory, and how a certain amount of familiarity is necessary to properly interact with a database.

There are a lot of database engines out there. As such, a developer or DBA will naturally have varying levels of experience with each, and some of this might conflict with how Postgres (PostgreSQL) operates. These kinds of embedded misunderstandings can cause potential issues by themselves, but in this particular case, corrective action is fairly simple.

Unlike a lot of programming languages that have loose typing, databases are extremely serious about data types. So serious in fact, many patently refuse to perform automatic type conversions in case the data being compared is not exactly equivalent afterwards. This is the case with Postgres (PostgreSQL) and surprisingly often, queries will suffer as a result. Fortunately this is something we can address!

When working with a database, sometimes performance problems are both far more subtle, and much worse than a query itself might suggest. The topic of this week’s Postgres (PostgreSQL) performance killers article concerns the use of the IN clause, and how misusing it can catastrophically obliterate the database in mysterious ways.

For the second of my ten part series on hidden Postgres (PostgreSQL) performance killers, I’m going to talk about something called an anti-join. It’s not a well-known approach outside of the database world, but due to how it works, it can impart almost magical plan revisions that drastically improve query performance in the right scenario. Developers can add it to a growing bag of tricks when working on database-driven content, since it comes in handy more often than you might expect.