What does ER stand for? An Entity Relationship (ER) diagram is one of the most important tools for database design. It helps you visualize the relationships between different entities and how they interact with each other. Many GUI tools have their own tools to build ER diagrams, e.g. pgAdmin IV, DBeaver, etc. In this blog […]

Intro On the 5th of February 2023, I had the privilege of giving a talk at the PostgreSQL devroom during FOSDEM 2023 titled “When it all GOes right.” My talk focused on the process of creating programs in the Go language using a PostgreSQL database. It was an incredible opportunity to share my insights and […]

© 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 […]

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 […]

UPDATE on 23.02.2023: This post explains how to install PostgreSQL on WSL2 for Windows, apply the necessary changes to PostgreSQL settings, and access the database from the Windows host. Even though this knowledge can be found in different bits and pieces spread out all over the internet, I want to compile a short and straightforward […]

© Laurenz Albe 2021 Most database tables have an artificial numeric primary key, and that number is usually generated automatically using a sequence. I wrote about auto-generated primary keys in some detail in a previous article. Occasionally, gaps in these primary key sequences can occur – which might come as a surprise to you. This […]

Today, I want to share some of the lessons learned when it comes to actually building an Oracle to PostgreSQL migration tool. Moving from Oracle to PostgreSQL has become a popular sport, widely adopted by many who want to free themselves from license costs, hefty support costs and also technical limitations on the Oracle side. […]

Over the years, many of our PostgreSQL clients have asked whether it makes sense to create indexes before – or after – importing data. Does it make sense to disable indexes when bulk loading data, or is it better to keep them enabled? This is an important question for people involved in data warehousing and […]

LATERAL joins are one of the lesser-known features of PostgreSQL and other relational databases such as Oracle, DB2 and MS SQL. However, LATERAL joins are a really useful feature, and it makes sense to take a look at what you can accomplish with them. Inspecting FROM more closely Before we dive into LATERAL, it makes […]

A “materialized view” is a database object which stores the result of a precalculated database query and makes it easy to refresh this result as needed. Materialized views are an integral feature of pretty much all advanced database systems. Naturally, PostgreSQL also provides support for materialized views, and offers the end-user a powerful tool to […]

Temporary tables have been around forever and are widely used by application developers. However, there is more to temporary tables than meets the eye. PostgreSQL allows you to configure the lifespan of a temporary table in a nice way and helps to avoid some common pitfalls. CREATE TEMPORARY TABLE … By default, a temporary table […]