Having generated a changelog on a current database, I have attempted to create a new database from that changelog. After a fair few problems probably related to our database structure, I've come across some strange behaviour.

When adding a primary key to a table consisting of two columns, the type of the column is changed from smallint(5) to int(11).

When adding a foreign key later in the script, this fails as the type of the two tables does not match anymore.

Any information as to why liquibase does that and how to prevent it from changing the type when adding a primary key? I can't find any mention of it in the docs or any other mention of this behaviour online.