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From Shaun Lindsay <>
Subject Couch clustering/partitioning Re: CouchSpray - Thoughts?
Date Fri, 20 Feb 2009 01:34:38 GMT
Hi all,
So, a couple months ago we implemented almost exactly the couch
clustering/partitioning solution described below.  The couch cluster (which
we called 'The Lounge') sits behind nginx running a custom module that farms
out the GETs and PUTs to the appropriate node/shard and the views to a
python proxy daemon which handles reducing the view results from the
individual shards and returning the full view.  We have replication working
between the cluster nodes so the shards exist multiple places and, in the
case of one of the nodes going down, the various proxies fail over to the
backup shards.

This clustering setup has been running in full production for several months
now with minimal problems.

We're looking to release all the code back to the community, but we need to
clear it with our legal team first to make sure we're not compromising any
of our more business-specific, proprietary code.

In total, we have:
a nginx module specifically set up for sharding databases
a 'smartproxy', written in Python/Twisted, for sharding views
and a few other ancillary pieces (replication notification, view updating,

Mainly, I just wanted to keep people from duplicating the work we've done --
hopefully we can release something back to the community in the next several

We're having a meeting tomorrow morning to figure out what we can release
right now (probably the nginx module, at the least).  I'll let everyone know
what out timeline looks like.

--Shaun Lindsay

On Thu, Feb 19, 2009 at 4:48 PM, Chris Anderson <> wrote:

> On Thu, Feb 19, 2009 at 4:35 PM, Ben Browning <> wrote:
> > So, I started thinking about partitioning with CouchDB and realized
> > that since views are just map/reduce, we can do some magic that's
> > harder if not impossible with other database systems. The idea in a
> > nutshell is to create a proxy that sits in front of multiple servers
> > and "sprays" the view queries to all servers, merging the results -
> > hence CouchSpray. This would give us storage and processing
> > scalability and could, with some extra logic, provide data redundancy
> > and failover.
> There are plans in CouchDB's future to take care of data partitioning,
> as well as querying views from a cluster. Theoretically, it should be
> pretty simple. There are a few small projects that have started down
> the road of writing code in this area.
> Sectional is an Erlang http proxy that implements consistent hashing
> for docs. I'm not sure how it handles view queries.
> There's also a project to provide partitioning around the basic
> key/value PUT and GET store using Nginx:
> If you're interested in digging into this stuff, please join dev@. We
> plan to include clustering in CouchDB, so if you're interested in
> implementing it, we could use your help.
> Chris
> --
> Chris Anderson

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