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https://issues.apache.org/jira/browse/COUCHDB-1259?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13490352#comment-13490352
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Jens Alfke commented on COUCHDB-1259:
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Benoit: I think you're misunderstanding the issue. This isn't something about
P2P. It's just that if the local CouchDB is not *listening* on a fixed port
number, then replications made by that server to/from another server aren't
handled efficiently ... even though the local server's port number has nothing
at all to do with the replication (since it's the one making the connections.)
In a real P2P case, this change makes even more sense, because the addresses of
the servers are unimportant -- as you said, it's the databases and their data
that are the important thing. A UUID helps identify those.
> Replication ID is not stable if local server has a dynamic port number
> ----------------------------------------------------------------------
>
> Key: COUCHDB-1259
> URL: https://issues.apache.org/jira/browse/COUCHDB-1259
> Project: CouchDB
> Issue Type: Bug
> Components: Replication
> Affects Versions: 1.1
> Reporter: Jens Alfke
> Assignee: Robert Newson
> Priority: Blocker
> Fix For: 1.3
>
> Attachments: couchdb-1259.patch, couchdb-1259.patch
>
>
> I noticed that when Couchbase Mobile running on iOS replicates to/from a
> remote server (on iriscouch in this case), the replication has to fetch the
> full _changes feed every time it starts. Filipe helped me track down the
> problem -- the replication ID is coming out different every time. The reason
> for this is that the local port number, which is one of the inputs to the
> hash that generates the replication ID, is randomly assigned by the OS. (I.e.
> it uses a port number of 0 when opening its listener socket.) This is because
> there could be multiple apps using Couchbase Mobile running on the same
> device and we can't have their ports colliding.
> The underlying problem is that CouchDB is attempting to generate a unique ID
> for a particular pair of {source, destination} databases, but it's basing it
> on attributes that aren't fundamental to the database and can change, like
> the hostname or port number.
> One solution, proposed by Filipe and me, is to assign each database (or each
> server?) a random UUID when it's created, and use that to generate
> replication IDs.
> Another solution, proposed by Damien, is to have CouchDB let the client work
> out the replication ID on its own, and set it as a property in the
> replication document (or the JSON body of a _replicate request.) This is even
> more flexible and will handle tricky scenarios like full P2P replication
> where there may be no low-level way to uniquely identify the remote database
> being synced with.
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