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From Thomas Mueller <muel...@adobe.com>
Subject Re: Concurrency Question
Date Wed, 30 Jan 2013 08:53:58 GMT
Hi,

As far as I understand, this was within one shard and replica (one
mongod). See also: http://www.infoq.com/news/2010/08/MongoDB-1.6

For scalable writes, we would need to write concurrently to different
shards. Even if all operations within one shard are synchronized (and I
don't think that's the case), Oak would still be scalable. Concurrent
operations within one mongod might improve performance / throughput
however.


The current MongoMK does have a scalability problem in my view, because
there is at least one collection that can't be sharded. But I guess this
is something we need to solve anyway, if we really want to have a scalable
solution.

Regards,
Thomas




On 1/29/13 11:42 PM, "Ian Boston" <ieb@tfd.co.uk> wrote:

>Hi,
>Are the concurrency characteristics of MongoDB [1] relevant to write
>concurrency in Oak ?
>
>IIUC from the presentation MongoDB pre 2.2 had global exclusive write
>locks and post 2.2 has per database exclusive write locks which might
>be scoped to the shard if the update only impacts a single shard.
>
>I am assuming that any storage implementation for Oak won't rely on
>this characteristic and could use a less synchronised storage
>mechanism from one of the other providers ?
>
>I ask, because I don't know if this is relevant, and want to be educated.
>
>Thanks
>Ian
>
>1 http://www.10gen.com/presentations/concurrency-internals-mongodb-v22


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