After going through this mail, and skimming through the Database
replication Guide (5.0),  multi-master replication is not provided out of
the Box (MarkLogic v 5.0-3).  Please correct me.

Can some one give me any other options for doing this.

I think the answer is "no". What you describe sounds like multi-master
replication. But flexible replication is single-master (and so are database
replication and forest replication).

What you could do is what the docs suggest: each cluster has DB1 and DB2,
each
operating as either master or replica.

cluster A: master DB1, replica DB2 cluster B: replica DB1, master DB2

If cluster A fails - due to a datacenter outage, say - you can shift load
for
DB1 to cluster B. But you cannot shift it back - or not without losing any
intermediate updates on B's copy of DB1. Instead you would have to set up a
new
cluster C as a new replication target.

cluster B: master DB1, master DB2 cluster C: replica DB1, replica DB2

Once cluster C has caught up, you could deliberately "fail" DB1 on cluster
B,
make cluster C the master for DB1, and build a new replica DB1 on cluster B.
Once cluster B has caught up, you have disaster recovery again.

cluster B: replica DB1, master DB2 cluster C: master DB1, replica DB2

That said, flexible replication is implemented in XQuery. So in theory it
is a
simple matter of programming for you or anyone else to extend it to
implement
conflict resolution. But that functionality is not part of MarkLogic Server
4.2
or 5.0.

-- Mike

On 16 Dec 2011, at 10:55 , Josh Warner-Burke wrote:

I am just beginning to read the documentation on ML flexible replication
(we are
using ML 4.2-5) and as I do, I wanted to check with you all to see if it is
going to work for what we want to do.

What we're looking to do is have two systems that are essentially like
failover
nodes for each other. They are in two different geographical locations, the
same installed codebase, and we wish for their databases to be kept in
sync.

Both nodes though support not just the displaying of information but the
updating of it. They are conceptually peers. The documentation uses the
terms
'Master' and 'Replica' databases, which in and of itself is just verbiage -
we
could easily pick a 'master' as long as the peer concept can work. However,
this section in the documentation is what gave me pause:

"Replicated databases do not necessarily need to be configured as entirely
a
Master or a Replica in the replication scheme. For example, you may have
two databases, DB1 and DB2,
where DB1 replicates updates to the documents in Domain A to DB2 and DB2
replicates
updates to the documents in Domain B to DB1.

Note: This is not a multi-master replication configuration, as the documents
updated by each application must be in different domains. Any overlap
between the
replicated domains may result in unpredictable behavior."

What we had hoped for is syncing of the same domains, the same documents,
in a
two-way sync. Conflict detection and resolution.

Is this possible using this feature? Any help at all is greatly
appreciated.

Josh Warner-Burke Tech Lead, Coral Reef 42Six Solutions

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-- 
Thanks & Regards
Sujith
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