Changing data type of 'createdAt' and 'updatedAt' fields in Sequelize model to DATE(6)

Question

Sequelize automatically adds a createdAt and a updatedAt field for every model, both of which are set to type DATE by default. I want to update this to DATE(6) to be able to make use of millisecond timestamps. I have two questions regarding this:

1. How do I go about creating a migration that enables this?
2. If I update the datatype to DATE(6), will the existing database records be unaffected and will only the newer ones have the millisecond timestamp?

Answer 1

1- The migration required to effect this change (presuming a cards table):

module.exports = {
    up: (queryInterface, Sequelize) => {
        return Promise.all([
            // cards
            queryInterface.changeColumn('cards', 'createdAt', {
                type: Sequelize.DATE(6),
                allowNull: true,
            }),
            queryInterface.changeColumn('cards', 'updatedAt', {
                type: Sequelize.DATE(6),
                allowNull: true,
            }),
        ])
    },

    down: (queryInterface, Sequelize) => {
        return Promise.all([
            // cards
            queryInterface.changeColumn('cards', 'createdAt', {
                type: Sequelize.DATE,
                allowNull: true,
            }),
            queryInterface.changeColumn('cards', 'updatedAt', {
                type: Sequelize.DATE,
                allowNull: true,
            }),
        ])
    }
};

2- The preceding migration runs an ALTER TABLE query on the cards table and all rows (previous ones and those that are yet to be inserted) will get the millisecond timestamp.