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From couchdb user <couchdbu...@gmail.com>
Subject Re: Replication Question
Date Sun, 03 Oct 2010 09:46:32 GMT
Hi Oguzhan,

On Fri, Oct 1, 2010 at 5:09 PM, Oguzhan Eris <eris@ekls.com> wrote:
> I'm trying to find some more information on how exactly replication
> "fits-in" with things like validation functions.
>
> My question is based on the following scenario.
>
> Have a cluster of cross replicating couchdb's where each can be
> written to independently.
>
> If a big network outage causes the clusters to be split,  the
> databases will continue to work on their side of the network and
> replicate to the ones they can access to.  So in this split brain
> scenario, we are likely to have conflicts when the network outage is
> restored.
>
> What I'd like to be able todo is, control replication through a
> validation function which is as simple as   if (oldDoc &&
> oldDoc.lastModifiedTime < newDoc.lastModifiedTime) { throw(forbidden)}
>
> Assuming timestamps are always in sync and lastmodifiedtime represents
> the time the doc was last updated by the respective system, all I want
> is to not have a document be replicated to my instance if I have a
> newer copy.
>
> I have tried various ways to mimic this behavior but I really can't
> tell if it's working and whether replication updates run through a
> validate_doc_update.
>
> I realize I can detect a conflict later and do something about it, but
> I really would prefer not to have conflicts at all and deal with them
> on-update instead of post-update.

I believe this is all handled internally by couchdb, it is part of the
bidirectional conflict resolution couchdb uses.

Regards,


>
> Thanks
>

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