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[protege-owl] Database and Owl Ontology

Timothy Redmond tredmond at stanford.edu
Mon Aug 17 09:15:13 PDT 2009


If you take an file-based owl project and convert it to a database  
backend project, the two projects will look identical in Protege.  In  
fact this is one of the tests that we run when working on the database  
backend.  We convert a file project to a database project and run a  
prompt diff.  If the diff turns up empty then that is a good thing.

In the Protege database schema, every ontology will have a different  
database table.  Imports are done through database repository  
repository manager.  There is a wiki page describing how to do this  
but I don't have access to the web at this moment.

-Timothy

On Aug 16, 2009, at 6:31 PM, Sarah G wrote:

>
>  Thanks, Tim.  Is there an example on protege's website on what an  
> ontology looks like when it is connected to a database?
> Also, when you import the database to the ontology should you select  
> each table to the appropriate class? Example:
> I would select the table called Vehicle that I imported from my  
> database into the ontology and select the class called vehicle in  
> the ontology to be mapped to each other is that correct? Thanks.
>
>
> From: tredmond at stanford.edu
> To: protege-owl at lists.stanford.edu
> Date: Sat, 15 Aug 2009 23:59:45 -0700
> Subject: Re: [protege-owl] Database and Owl Ontology
>
>
>
> There are several reasons why people would want to put a very large  
> ontology into a database.  For example,
>
> 1. a database can be loaded on a machine with limited memory.  This  
> allows people to work with ontologies on machines with limited  
> capabilities when access to more capable machines is  not possible.
>
> 2. an ontology in a database can be loaded very quickly allowing  
> people to access an ontology without having to (re)parse the entire  
> ontology
>
> 3. a server may need to open many ontologies open at the same time  
> and to be able to open large ontologies quickly based on demand from  
> users or clients.  This is important for an ontology repository for  
> example.
>
> The main reason for  not wanting to use a database backend is its  
> complexity and its much slower performance.
>
> But it is also important to point out that the Manchester OWL api  
> (used by Protege 4) can hold very large ontologies in limited  
> memory.  So for example, my 2GB old laptop is almost capable of  
> loading snomed.  This may suggest that the most important reason for  
> having a database backend for the Manchester OWL API is the third  
> case.
>
> -Timothy
>
> On Aug 15, 2009, at 7:48 PM, Sarah G wrote:
>
> Hi All,
>
> Could someone please explain why you should have/use a relational  
> database as backend for an ontology? I am new to using owl and was  
> wondering why or if I will need to have a database.
>
> Thanks,
>
> Sarah
>
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