// Composite Index: Nested structure.
	Data1A string `gorm:"index:,composite:comp_id1"`
	CompIdxLevel1C

	// Composite Index: Unique and priority.
	Data2A string `gorm:"index:,unique,composite:comp_id2,priority:2"`
	CompIdxLevel2C
}

type CompIdxLevel1C struct {
	CompIdxLevel1B
	Data1C string `gorm:"index:,composite:comp_id1"`
}

type CompIdxLevel1B struct {