Re: [Monotone-devel] newbie question - SHA1 vs serials

[Jon Bright]

Hi,

K. Richard Pixley wrote:
> To provide globally unique serials, one would need to include some 
> representation of the location at which an event occurred.  In this 
> case, I'd suggest the domain name of the machine involved.  So something 
> like 1:monotone.venge.com, 2:monotone.venge.com, etc.  If each 
> repository used it's own name, (presumably it's domain name in most 
> cases), and kept it's own list of serials, wouldn't this both provide a 
> guaranteed unique id as well as providing that oh-so-sought-after 
> monotonically increasing number people so love to see?

It's an idea that's been considered, but has a number of difficulties:

1. Not everyone's machine has a (valid) domain name.  I have a number of 
domains, so I could pick one, but if I didn't, the only name I'd have 
would be p34543522.dip.t-dialin.net or whichever name my ISP gives me today.

2. I could be operating two (or more) separate monotone DBs on the same 
machine.  OK, we could make some special effort to try and get the two 
copies to know about each other's numbers.

3. I have machine foo.bar.com - what to do about some unpleasant person 
who decides to incorrectly name their machine foo.bar.com too?  (There 
are a number of workarounds for this, each with advantages and 
disadvantages)

4. The number's not actually monotonically increasing when viewing the 
tree as a whole.  Ignoring branches, I'd still get

1:foo.bar.com
      |
1:baz.foo.com
      |
2:baz.foo.com
      |
3:baz.foo.com
      |
4:baz.foo.com
      |
5:baz.foo.com
      |
2:foo.bar.com

...which kind-of seems to defeat the point.

--
Jon Bright
Silicon Circus Ltd.
http://www.siliconcircus.com