© Laurenz Albe 2023 Many people have heard that ALTER DEFAULT PRIVILEGES makes it easy to allow other users access to tables. But then, many people don’t understand the command in depth, and I hear frequent complaints that ALTER DEFAULT PRIVILEGES does not work as expected. Read on if you want to know better! Default […]

© Laurenz Albe 2023 Different from many other database systems, PostgreSQL does not support query hints. That makes it difficult to force the hand of the query planner when it comes to a certain join order that you know to be good. This article explains how you can influence execution plans in PostgreSQL. Why no […]

SQL and numeric constants NEW in PostgreSQL 16 – support for underscores in integer and numeric constants! I already wrote about support for different notations in the upcoming PostgreSQL 16. This new major version also implements the SQL:202x standard (draft), allowing you to use underscore separators for integers and numeric constants. Using underscore separators in […]

© Laurenz Albe 2023 I am on a spree! After writing about breaking your database and transaction ID wraparound, here I am writing about damage caused by CHECK constraints! Trust me, I don’t want to destroy PostgreSQL databases. It’s just that this Twitter message was brought to my attention and triggered memories of other reports […]

A join is a concept in IT which is widely used and often referred to but rarely really understood. What are the differences between inner joins, outer joins, semi joins and so on? Let’s shed some light on them and see how inner and outer joins really work. Producing sample data Before we can get […]

Running ALTER TABLE … ADD COLUMN can have side effects which have the potential to cause serious issues in production. Changing data structures is an important issue and happens often, therefore it’s important to understand what is really going on. Let’s dive in and see how to run ALTER TABLE … ADD COLUMN in a […]

Bonus cards, “Miles & more”, bonus points – don’t we all love and hate them at the same time? Recently we had an interesting use case which made me think about sharing some of the techniques we used in this area to reduce client code by writing some clever SQL. This post will show you […]

  © Renée Albe 2022 Case-insensitive search is a much-requested feature, partly (I suspect) to maintain compatibility with Microsoft SQL Server. There are several solutions to the problem, one of which is to use case-insensitive ICU collations. This works like a charm, except if you want to perform pattern matching. So let’s have a closer […]

© Laurenz Albe 2022 Next to character encoding, time zones are among the least-loved topics in computing. In addition, PostgreSQL’s implementation of timestamp with time zone is somewhat surprising. So I thought it might be worth to write up an introduction to time zone management and recommendations for its practical use. Time zones and the […]

It’s been many years since the first ideas to implement the MERGE command surfaced on the PostgreSQL mailing list. Now this important feature has finally made it into PostgreSQL core, in PostgreSQL 15. To show people how this vital command works, I have decided to come up with a technical preview to introduce my readers […]

© Laurenz Albe 2022 Table partitioning is one of the best-liked features out of the more recent PostgreSQL developments. However, there is no support for automatic partition creation yet. This article shows what you can do to remedy that. Use cases for automatic partition creation There are essentially two use cases: Create partitions triggered by […]

Normalization by Osmosis Part 2: Practical Examples of Data Normalization in PostgreSQL Having gone through a theoretical introduction in part 1, it is now time to discuss some more practical examples. I’ll first talk about the… type modeling … of columns. It is important to realize that during the time Codd formulated the base 3 […]