Microservices centralized database model

Question

Currently we have some microservice, they have their own database model and migration what provided by GORM Golang package. We have a big old MySQL database which is against the microservices laws, but we can't replace it. Im afraid when the microservices numbers start to growing, we will be lost in the many database model. When I add a new column in a microservice I just type service migrate to the terminal (because there is a cli for run and migrate commands), and it is refresh the database.

What is the best practice to manage it. For example I have 1000 microservice, noone will type the service migrate when someone refresh the models. I thinking about a centralized database service, where we just add a new column and it will store all the models with all migration. The only problem, how will the services get to know about database model changes. This is how we store for example a user in a service:

type User struct {
    ID        uint           `gorm:"column:id;not null" sql:"AUTO_INCREMENT"`
    Name      string         `gorm:"column:name;not null" sql:"type:varchar(100)"`
    Username  sql.NullString `gorm:"column:username;not null" sql:"type:varchar(255)"`
}

func (u *User) TableName() string {
    return "users"
}

Answer 1

Depending on your use cases, MySQL Cluster might be an option. Two phase commits used by MySQL Cluster make frequent writes impractical, but if write performance isn't a big issue then I would expect MySQL Cluster would work out better than connection pooling or queuing hacks. Certainly worth considering.