AutoMigrate drop unique index that already exists on mysql table

[seanlook]

Your Question

I've a column definition like:

EventUuid string `json:"event_uuid" gorm:"type:varchar(60)"

There's no unique constraint. In my situation, I add a unique index on this table

ALTER TABLE ADD UNIQUE INDEX uk_eventuuid(event_uuid)

Then when I run db.Migrator().AutoMigrate(&m), the unique index is dropped

The document you expected this should be explained

Does this is a feature or bug?

Expected answer

If it's a feature, the docs need to mention it out. But I prefer it as an unexpected bug, because it removed my unique index.