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From Demetrius Nunes <>
Subject Re: CouchDB x RDF databases comparison
Date Thu, 07 May 2009 20:11:25 GMT
Hi Nitin,

Great answer. Thanks a lot. One more question...

I am in the Javaland here, so another viable option for my application is
using JCR, such as the Apache Jackrabbit implementation.

Did you happen to take a look at that as well? I think JCR has even more
similarities with CouchDB than RDF.

How would you compare JCR and CouchDB ?

Thanks a lot,

On Thu, May 7, 2009 at 5:04 PM, Nitin Borwankar <> wrote:

> Demetrius Nunes wrote:
>> Hi there,
>> We are evaluating new technologies for managing semi-structured data and
>> documents in one of our applications. We've got tired of wrestling
>> relational databases for this.
>> I would like to know why would I prefer to use CouchDB instead of a RDF
>> database, such as Sesame ou Mulgara.
>> I know some of the RDF advantages, such as open standards,
>> interoperability,
>> rules engines, semantic queries, community and tool support, maturity,
>> etc.
>> But I really like the simplicity of the CouchDB model.
>> Can anyone enlighten me?
>> Thanks a lot,
>> Demetrius
> Hi Demetrius,
> We ( have investigated and used SQL databases, RDF store
> (Virtuoso) and CouchDB for bibliographic metadata management.  I am the
> project manager and data architect for this project.
> Relnl databases are a first choice often but have many limitations in
> management of loosely typed, messy, string based data sets.  So we are in
> agreement on not using that technology.
> We,,  need both the schemalessness of CouchDB at one end of our
> workflow and the strongly-typedness of RDF at the other end of the workflow
> when all our data has been cleaned up and "ontologized". So we don't see
> this as an either/or between CouchDB and RDF stores.
> However we can definitely say one thing  - if you need  just the flexible
> schema aspect  and are using RDF to give you that, then  that is massive
> overkill and the conceptual overhead of the RDF (ontology, schemas,
> namespaces, completely normalized everything ie URI's for subject,
> predictae, object) , is simply not worth it.    If however you want to do
> logical inference and reasoning over your data then clearly the RDF and
> semantic  machinery gives you  a  whole lot of goodness that is worth the
> overhead.
> So CouchDB is not a substitute for an RDF-store, but you may be using an
> RDF-store for the lesser things it gives you (flexible schema) and in that
> case CouchDB can do a lot more for you at a much lower overhead and much
> greater ease of use and integration into existing tools.
> Additionally SPARQL  (like SQL) is not really meant for text search which
> is critical for loosely typed data. So even at our RDF end we have a Solr
> instance for rapid text search over the RDF store.
> Additionally we have couchdb-lucene as an extension on our CouchDB instance
> and this has given us everything we need at the loosely typed data end of
> our workflow.
> So if semi-structured data and document management is your primary use case
> and there is no semantic/ontology/inference component then forget RDF-stores
> and just go with CouchDB.
> In our project we are developing a format on top of JSON to export
> bibliographic metadata for integration into JSON friendly date consumers, it
> also happens to have easy mapping to RDF.
> So even if you go to Couch now you may be able to integrate into an
> RDF-store at some later stage if the need arises.
> Hope this helps,
> Nitin Borwankar,
> Project Manager,  Bibliographic Knowledge Network


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