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From A J <s5a...@gmail.com>
Subject Re: Ditching Cassandra
Date Wed, 30 Mar 2011 20:39:14 GMT
I did an apple to apple comparison of WRITE speed of Mongo vs Cassandra.

Benchmarking (Cluster of 4 machines. Each of 4 cores and 15gb ram. 2
IN region1 but different zones, 1 in region2 and 1 in region3. Set
consistency level of 3. i.e. atleast 3 machines have to confirm of
write before the write is confirmed as done to client. also fsync kept
at 10 seconds ). Same specs and hardware for both mongo and cassandra.

I modified stress.py to work both for mongo and cassandra.

Conclusion: Cassandra write speed is twice that of Mongo for same
settings of CL and durability!

Though I agree the documentation and ease of use of Mongo is much
superior to Cassandra, the write speed and lesser hoops in sharding
keeps the options in balance. (MongoDB needs additional Mongos server
and config server. Data has to channel through the MongoS to the
shards)
Because Mongo is commercially backed, you would expect the edges to be
smoother on that.
Also CL for reads is not possible in MongoDB. So I am expecting reads
too to be worse on Mongo (as I will always have to hit the primary to
ensure consistency). Not tried testing yet.
You also have to consider the fact 10gen can get acquired anytime.




On Wed, Mar 30, 2011 at 12:55 AM, Colin <colpclark@gmail.com> wrote:
> Thank you Eric.  I appreciate it.
>
> -----Original Message-----
> From: Eric Evans [mailto:eevans@rackspace.com]
> Sent: Tuesday, March 29, 2011 11:47 PM
> To: user@cassandra.apache.org
> Subject: Re: Ditching Cassandra
>
> On Tue, 2011-03-29 at 20:56 -0500, Colin wrote:
>> Are you saying that 8 will or not be compatible with 7?
>
> You will be able to perform a rolling upgrade from 0.7.x to 0.8.  That is to say, you'll
be able to upgrade each node one at a time, mixing 0.7 and 0.8 nodes until the upgrade is
complete.
>
>> If not, would you recommend waiting until 8?  We have done an awful
>> lot of work, have an awful  lot of work left, and have become very
>> frustrated.
>
> If you're interested in exploring the CQL route, and if your time-line permits it, that's
what I would do.
>
>> Any idea on when 8 will be available?
>
> Provided nothing crops up, we'll freeze on April 11th (2 weeks from yesterday), and release
on the week of May 9th (4 weeks later).
>
> --
> Eric Evans
> eevans@rackspace.com
>
>
>

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