You don't need to add columns to the session table since session data is serialized as JSON (in most cases) when stored to the database, including any custom fields added to it.

When the server pulls the session from the storage it is deserialized and you can access those custom fields.

Note that if you are using connect-session-sequelize, you have the option to configure extendDefaultFields which affect your ability to query session data by those specific fields, but it is not mandatory in order to store custom fields as part of the session data object.