© Laurenz Albe 2022 I have been faced with a request for an unusual unique constraint that puzzled me for a while. Since the solution I came up with is a nice show-case for range data types, I’ll share it with you. Also, it allows me to rant some about NULL, which is a temptation […]

© Laurenz Albe 2022 A while ago, I wrote about the performance impact of query parameter data types. Recently I encountered a similar problem with UNION ALL that baffled me for a while, so I’d like to share it with you. UNION ALL to implement polymorphism Different entities can have something in common. For example, […]

serial is a popular pseudo data type in PostgreSQL which is often used to generate auto-increment columns. However, this can lead to issues which are often underestimated. So what is the problem? Some of you might have already seen the following error message in real life: What happened here is that the underlying integer column […]

© 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 […]

Understanding Multiranges Range types have been around in PostgreSQL for quite some time and are successfully used by developers to store various kinds of intervals with upper and lower bounds. However, in PostgreSQL 14 a major new feature has been added to the database which makes this feature even more powerful: multiranges. To help you […]

© Laurenz Albe 2022 Recently, I could help solve a “mysterious” performance problem for a customer. The problem turned out to be a badly chosen query parameter type, which led to poor query performance. After working on this customer’s case, I realized that the meaning of the data type of a query parameter is not […]

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 […]

Normalization by Osmosis Part 1: A Guide to Data Normalization in PostgreSQL  By Michał Małecki Introduction Although I installed my first PostgreSQL database on RedHat Linux (not RHEL) 6.0 around 1999, I probably limited my interaction with this 6.5 release to starting the server with SysinitV scripts. PostgreSQL was at that time an underdog to […]

Creating auto increment columns in PostgreSQL is easy. Simply use two pseudo data types serial and serial8, respectively, then PostgreSQL will automatically take care of your auto increment columns. However, once in a while problems can still occur. Let us take a look and see. Sequences: Avoid manual values To understand the underlying problem, one […]

PostgreSQL allows end users to store BLOBs (binary large objects) in the database. Many people use these functions to handle data directly in SQL. There has long been a discussion about whether this is a good thing or not. We expect that particular discussion to go on indefinitely. However, if you are in the “pro […]

Data types are an important topic in any relational database. PostgreSQL offers many different types, but not all of them are created equal. Depending on what you are trying to achieve, different column types might be necessary. This post will focus on three important ones: the integer, float and numeric types. Recently, we have seen […]

UPDATED 08.05.2023 – SQL and especially PostgreSQL provide a nice set of general purpose data types you can use to model your data. However, what if you want to store fewer generic data? What if you want to have more advanced server-side check constraints? The way to do that in SQL and in PostgreSQL in […]