i know counting objects, aka, distributed auto-increment in couch is
consider bad form. but let me propose a scenario a feel out peoples
thoughts on a specific topic, in the interest in solving what i think
*must* be solvable problem when using couch for an actual, real, live
distributed system..
so let's say we want to store something
login: foo
password: bar
in a couchdb system, to authenticate users. clearly, when given a
login, we want to lookup a given login by said login and validate a
password.
so consider this a bit - we could store docs using "account-
#{ login }" or some other permutation of of the login name - the md5..
whatever...
this obviously isn't great - two user signing up on two different
nodes will cause a collision at replication time, but not at sign up
time, meaning it'd be nearly impossible to actually create a system
with multi-master nodes that would allow something as simple as user
signup without crazy after the fact email resolution requiring a user
to re-signup iff their login was a dup.
okay, take two, let couch generate the uuid, and replication proceeds
as planned. all is well. that is, until you want to authenticate a
user... doing a search based on
emit( doc.login, doc )
returns 14 results. two of them have the same password. which user
*is* this client logging in?
so this seems like a real wart: replication is *useless* without a
better mechanism for generating uuids. clearly we cannot expect a
user to login via uuid, and clearly we cannot use the login, nor
login:password combined as the uuid since that would create retro-
active signup failures...
so, in a situation like this, requiring a unique set of data across
all replicating systems, what would the 'couch way' be?
i think i'm stuck thinking inside a box and would love some insight to
get out of it but, for now, i feel like the distributed and replicated
nature of couch, while solving a host of issues, seems to open up
vastly more complicated ones in the process.
kind regards.
a @ http://codeforpeople.com/
--
we can deny everything, except that we have the possibility of being
better. simply reflect on that.
h.h. the 14th dalai lama
