I am working on a new section of my CouchDB library to synchronize a Couch
database with a local array. Before I wade too far in, I wanted to get to
see if my plan makes sense..

I have two questions I'm hoping for input on:
1. Can anyone think of a scenario I am missing?
2. Is there anything missing from the conflict resolution options?

CouchDB uses revision numbers to keep track of changes, so I am trying to
map out all the possible scenarios that should exist.

quick definitions:
   localRev: revision number of the local document from last sync
   serverRev: revision number of the server document
   localDirty: boolean flag that says that the local document has been
edited since last sync  
Comparing each document's rev numbers, I envision the following scenarios:
1. document is unchanged
localRev = serverRev AND localDirty = false
action: ignore during sync

2. server document is newer
localRev < serverRev AND localDirty = false
action: download latest version

3. document has been edited locally, local copy is the same as server
localRev = serverRev AND localDirty = true
action: upload new version

4. document has been edited locally, BUT server copy is newer
localRev < serverRev AND localDirty = true
action: depends on conflict resolution settings (see below)

5. local document doesn't exist
localRev = empty and serverRev > 0
action: download document

6. local document is new, doesn't exist on server yet
localRev > 0 and serverRev = empty
action: upload document

7. The revision number is generated by the server, so there should be no
reason why localRev > serverRev unless the user has switched to a different
server that has been replicating with the original, and is behind.
action: it's an unlikely scenario... upload local document

8. if the record is marked as deleted locally or on the server, it is
deleted everywhere

Conflict resolution:
These are the options I am planning on for conflict resolution, they will
get passed as a param in the sync function

local: in conflict, keep local, discard server
server: in conflict, keep server, discard local
localmerge: keep local document, insert server document as a subkey in local
document "conflict"
servermerge: keep server document, insert local document as a subkey in
local document "conflict"
keepboth: rename "_id" of local document and upload it, download server

Greg (pink) Miller
mad, pink and dangerous to code
View this message in context: 
Sent from the Revolution - User mailing list archive at Nabble.com.

use-livecode mailing list
Please visit this url to subscribe, unsubscribe and manage your subscription 

Reply via email to