Can anyone explain how the UUID() function works?

Eugaia · March 29, 2018, 6:42am

Hi,

I’m curious to know how the UUID() function in N1QL works. Can anyone give a rough overview?

Thanks.

vsr1 · March 29, 2018, 12:48pm

Eugaia · March 29, 2018, 12:52pm

Thanks for replying.

I’m specifically interested in the UUID() function itself. i.e. How is the full UUID generated? What variables are used to create a unique ID over the whole cluster?

Thanks.

vsr1 · March 29, 2018, 12:55pm

UUID generates a random UUID according to RFC 4122

github.com

couchbase/query/blob/master/util/uuid.go#L33


func init() {
	uuidPool = &sync.Pool{
		New: func() interface{} {
			b := make([]byte, _UUID_SIZE, _UUID_SIZE)
			return b
		},
	}
}


// UUID generates a random UUID according to RFC 4122
func UUID() (string, error) {
	uuid := uuidPool.Get().([]byte)
	defer uuidPool.Put(uuid)


	n, err := io.ReadFull(rand.Reader, uuid)
	if n != len(uuid) || err != nil {
		return "", err
	}
	// variant bits; see section 4.1.1
	uuid[8] = uuid[8]&^0xc0 | 0x80
	// version 4 (pseudo-random); see section 4.1.3

Eugaia · March 29, 2018, 1:00pm

@vsr1 Perfect, thanks!