Articles tagged with "SQL"
Getting the last value of a group in an aggregated query in PostgreSQL is a challenging task. In this article we present a simple way to get the first or last value of a group using group by.
If you ever had to maintain a traffic heavy Django site, you probably had to deal with graceful migrations. In the article I explain what atomic and reversible migrations are, how to execute "raw" SQL in migrations the right way, and how using a little known migration command we can completely alter the Django migrations built-in behavior.
How we cut a heavy admin dashboard response time in half with advanced SQL and some Django hackery. I recently had the pleasure of optimizing an old dashboard. The solution we came up with required some advanced SQL that Django does not support out of the box. In this article I present the solution, how we got to it, and a word of caution.
A while back we started getting alerts in the middle of the night on low disk space. A quick investigation led us to one of our ETL tasks. Every night the task was fired to eliminate duplicate dumps, and free up some space. This is a short story about how we found our silver bullet and solved the issue without adding a single byte of storage.
Common table expressions, also known as the WITH clause, are a very useful feature. They help break down big queries into smaller pieces which makes it easier to read and understand. But, when used incorrectly they can cause a significant performance hit.
ORMs offer great utility for developers but abstracting access to the database has its costs. Developers who are willing to poke around the database and change some defaults often find that great improvements can be made.
I started my programming career as an Oracle DBA. It took a few years but eventually I got fed up with the corporate world and I went about doing my own thing. After I gotten over not having proper partitions and MERGE statement, I found some nice unique features in PostgreSQL. Oddly enough, a lot of them contained the word DISTINCT.
