mongodb

c, err := mongodb.Dial("localhost", 10)
if err != nil {
	fmt.Println(err)
	return
}
defer c.Close()

// session
s := c.Ref()
defer c.UnRef(s)
err = s.DB("test").C("counters").RemoveId("test")
if err != nil && err != mgo.ErrNotFound {
	fmt.Println(err)
	return
}

// auto increment
err = c.EnsureCounter("test", "counters", "test")
if err != nil {
	fmt.Println(err)
	return
}
for i := 0; i < 3; i++ {
	id, err := c.NextSeq("test", "counters", "test")
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Println(id)
}

// index
c.EnsureUniqueIndex("test", "counters", []string{"key1"})

Output:

1
2
3