Primary Keys vs. UNIQUE Constraints in PostgreSQL
Most of my readers will know about primary keys and all kinds of table constraints. However, only a few of you may have ever thought about the difference between a primary key and a UNIQUE constraint. Isn’t it all just the same? In both cases, PostgreSQL will create an index that avoids duplicate entries. So […]
Gaps in sequences in PostgreSQL
© 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 […]
UUID, serial or identity columns for PostgreSQL auto-generated primary keys?
© Laurenz Albe 2021 UPDATED 14.05.2022: Sometimes customers ask me about the best choice for auto-generated primary keys. In this article, I’ll explore the options and give recommendations. Why auto-generated primary keys? Every table needs a primary key. In a relational database, it is important to be able to identify an individual table row. If […]