On 12/01/2009, at 10:26 PM, Noah Slater wrote:
On Mon, Jan 12, 2009 at 05:15:39PM +1030, Antony Blakey wrote:
--- Revised Proposal ---------
Each document, whether canonical or derived, has a globally unique
identity consisting of a UUID and the document ID.
In the case of a canonical document, the UUID is the UUID of the
database (or cluster), which is assigned when a database is created.
In the case of a (derived) view map result, it is the UUID of the map
function (not the design doc), which is assigned to each map function
(i.e. view) in a design doc when the design doc is created or
updated.
Furthermore, there is a triple {UUID, document id, document rev} that
globally identifies a document at a given point in time. The key
characteristic being that a {UUID, id, rev} identifies an immutable
value.
Why use UUID like this? Why not let the database (&c) name suffice?
Because if the database is deleted and the name reused, intermediaries
can't tell. We presume that's not likely, but in a world of database-
per-user (as discussed on IRC recently), which could conceivable be
extended to domains other than users, who nows what the future might
bring. The same goes for _externals wanting to invalidate secondary
indexes in such a scenario.
i.e. the UUID of a database represents a context in which (id + rev)
is immutable. If you use the db name, that's no longer true because
you no longer have a globally unique namespace.
Antony Blakey
--------------------------
CTO, Linkuistics Pty Ltd
Ph: 0438 840 787
Isn't it enough to see that a garden is beautiful without having to
believe that there are fairies at the bottom of it too?
-- Douglas Adams
