incubator-couchdb-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Googcheng <>
Subject RE: Replication Configuration
Date Thu, 24 May 2012 00:24:56 GMT
Is it necessary?  Why, i don't understand. 

Ajay Pawaskar <>编写:

>Thx jens,
>	I am going with keeping one couch DB server for write operation and at the same time
replicating updated documents for read on other server
>-----Original Message-----
>From: Jens Alfke [] 
>Sent: Wednesday, May 23, 2012 2:42 AM
>Subject: Re: Replication Configuration
>On May 22, 2012, at 3:45 PM, Ajay Pawaskar wrote:
>                 Can I start Replication on Both Servers
>                                               AC è BC
>                                               BC è AC ?
>Sure, bidirectional replication is very common.
>               If yes then what will be probability of overwriting Data of AC by BC or
vice a versa (as load balancer is in between I don't know which server is going to update[I
am updating couch from .net app])
>CouchDB will never overwrite data. What can happen is a conflict, if the same document
is updated differently on both servers and then replicated across. Your app will need to detect
the conflict, resolve it by comparing both conflicting revisions, and write the resolved document
back to the database.
>It's also possible to structure your system to avoid conflicts, for example by routing
all write requests so that any individual document will only ever be updated on one server.
You can do this pretty easily by taking a hash of the document ID, modulo the number of servers,
and sending the request to the server with that index.
View raw message