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From Sebastian Cohnen <sebastiancoh...@googlemail.com>
Subject Re: Comparison of MongoDB & CouchDB: MongoDB seems better on insert
Date Mon, 20 Dec 2010 22:20:38 GMT
question inside :)

On 20.12.2010, at 23:02, Jan Lehnardt wrote:

> Hi,
> 
> On 20 Dec 2010, at 22:32, Chenini, Mohamed wrote:
> 
>> Hi,
>> 
>> I found this info on the net at http://www.slideshare.net/danglbl/schemaless-databases
>> [...]
>> Does anyone knows if this was verified?
> 
> I think the author's comment on slide 35 sums it up pretty nicely:
> 
> "Of course this is just one (lame) test."
> 
> Coming up good numbers is hard which means that people with easy ways to make them come
up with bad ones.
> 
> I've written about the difficulties on benchmarks databases on my blog:
> 
>  http://jan.prima.de/~jan/plok/archives/175-Benchmarks-You-are-Doing-it-Wrong.html
>  http://jan.prima.de/~jan/plok/archives/176-Caveats-of-Evaluating-Databases.html
> 
> They should give you a few pointers on why this is hard.
> 
> --
> 
> To the point: CouchDB generally performs best with concurrent load. In the case of loading
data into CouchDB, bulk requests* will speed up things again. To push CouchDB to a write limit,
you want to use concurrent bulk requests (specific numbers will depend on your data and hardware).

Does this really speed up things? I've tried this approach (concurrent bulk inserts) with
small/big docs and small/big bulk chunk sizes: the difference was not significant. I thought
this was reasonable, since writes are serialized anyways. The setup was one box generating
documents, creating bulks and keep them in memory and bulk insert batches of complete docs
(incl. simple monotonic increasing ints as doc ids) to another node. delayed commit was off.

> 
> * http://wiki.apache.org/couchdb/HTTP_Bulk_Document_API
> 
> Unfortunately this means that these one-off benchmarks don't show any good numbers for
CouchDB, yet fortunately this shows easily that these one-off benchmarks don't really reflect
common real-world usage and should be discouraged.
> 
> Hope that helps, let us know if you have any more questions :)
> 
> Cheers
> Jan
> -- 
> 


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