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From Shaun Lindsay <sh...@meebo.com>
Subject Re: Couch clustering/partitioning Re: CouchSpray - Thoughts?
Date Fri, 20 Feb 2009 02:05:36 GMT
Our current cluster is running on 4 nodes, on some slower, leftover
hardware.  As of right now, it's handling about 300 queries/sec, with about
1/3 of that being view requests.  As for documents, we're looking at ~12M
docs taking up around 90Gb of space on disk.
We have the cluster split in to 48 shards, with 12 shards per node -- this
lets us add more nodes later, up to 48, before we need to mess with
resharding the data (or, more likely, treeing out underneath the first level
of nodes).

We've also implemented some caching for the most often hit views in the
smartproxy -- map/reducing over the 48 shards isn't trivial and, at 100 view
queries a second, caching is necessary for the cluster to actually work.

--Shaun Lindsay
Meebo.com

On Thu, Feb 19, 2009 at 5:40 PM, Chris Anderson <jchris@apache.org> wrote:

> On Thu, Feb 19, 2009 at 5:34 PM, Shaun Lindsay <shaun@meebo.com> wrote:
> > 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,
> > etc)
> >
> > 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
> > weeks.
> >
> > 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.
> >
>
> This is really cool. It sounds like a tool people could get started
> with right away to build big CouchDB clusters. Is there anything you
> can tell us about the size of clusters you've used?
>
> The smartproxy code will probably be a really good illustration of
> what we'll probably want to implement in Erlang for CouchDB,
> eventually. Again, +1 for software people can use today.
>
> Hopefully it turns out to be easy to release!
>
> Cheers,
> Chris
>
> --
> Chris Anderson
> http://jchris.mfdz.com
>

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