Gnoosic.com has been running for over 10 years. A user first tells Gnoosic artists they like. Then the user is presented with other artists he might like and he can pick which ones he likes and which ones he doesn't. As time goes by, Gnoosic learns more about what users like and stores those preferences in a database.

Among other information, Gnoosic also stores the popularity of different bands. This information is stored as an integer data type. So, the popularity field for the entry about Pink Floyd reached 1.3 billion. The maximum allowed for the INT data type is 2.1 billion (more precisely, 2,147,483,647 ) . After discussion, and identifying the motivation behind the project, a collaboration emerged with the aim to develop a tool that would check for situations like these so they can be avoided.

Running the tool uncovered a few other columns in different tables of the Gnoosic database that required attention, and since this tool was built to support decisions about the schema of MySQL database, it was opensourced under MIT license.

In addition to the main use-case, there is a dual use-case. If the tool shows that the maximum values stored in a column are a long way from reaching the maximum, and if the data type allows (for text data types), the length of these columns can be fine-tuned for more efficient use of disk space.