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From Robert Newson <rnew...@apache.org>
Subject Re: Two way replication question
Date Mon, 29 Jul 2013 19:48:10 GMT
correct.

On 29 July 2013 20:14, James Marca <jmarca@translab.its.uci.edu> wrote:
> On Mon, Jul 29, 2013 at 07:47:10PM +0100, Robert Newson wrote:
>> CouchDB will check that the current revision of every document is
>> present on the target and will skip copying it if it is. In your case,
>> the replication will not transfer any documents at all but will check
>> every id/rev pair which will take some time.
>
> Okay thanks.
>
> Is this also true if I pull and push from the same machine.  That is,
> if I set up pull replication on A to pull from B, in parallel with the
> push from B to A?
>
> My understaing is that the two replication jobs (push A to B, pull B
> to A, both running on A) would be totally independent and would not
> share information about B's db state.  Correct?
>
> Thanks,
> James
>
>>
>> B.
>>
>>
>> On 29 July 2013 19:37, James Marca <jmarca@translab.its.uci.edu> wrote:
>> > Hi,
>> >
>> > I have two machines, A and B.  I am running an analysis on A, saving
>> > the output to couchdb, and then replicating by push from A to B.
>> >
>> > B's database started life from this push replication, and has never
>> > been otherwise modified.  So the two are more or less identical.
>> >
>> > What I want to do now is parallelize my work flow and run more
>> > analyses on B, save locally (to B's couchdb), and then replicate those
>> > changes to A.  (The database is used both to save output, and also to
>> > keep track of what has been done already, so it is useful to keep the
>> > output db syncronized between all machines.)
>> >
>> > My question is whether replicating from B to A will require pushing
>> > all of the docs to A.  This is an issue because my database is 21 GB
>> > and growing, and I'd rather not push all that data from B to A when I
>> > *know* the two are identical right now.
>> >
>> > Is there a way to set up replication to skip everything already there?
>> > Or to copy the replication state from A to B so that B knows that
>> > replication with A can start with new data only?
>> >
>> > If not, I can of course just save work done on B to the CouchDB on A
>> > directly, but I'd rather set it up so that the computation process
>> > always just hits couchdb on localhost, and let couchdb do the machine
>> > to machine copying.
>> >
>> > Thanks for any insights or pointers to the correct docs page,
>> >
>> > James Marca

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