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Re: 3 basic questions
On Mon, 24 Sep 2001, you wrote:
> Hello,
>
> I am trying to evaluate Ozone for use in my application and I have a few questions that don't seem to be covered in the documentation.
>
> 1. I am wondering if anyone has done any testing, any benchmarking that shows how Ozone performs as the number of persisted objects increases?
> I know this depends on the number of factors, from hardware to object complexity, but I'd be interested in any benchmarks or any experiences that people can share.
>
> 2. This question is about object design and the loading of objects from the DB.
> The application I am writing has a component that fetches web documents, stores them (with the help of something like ozone), and then performs some other actions on those documents.
> Each web server can have lots (hundreds, thousands, or tens of thousands) of web documents associated with it.
> I am trying to figure out how to design my objects so that they don't cause duplication of data (e.g. all documents from the same web server have the same host name associated with them) in order to slow the growth of the database of web documents.
>
> My concrete questions in regards to this problem and Ozone are:
> - If I have an object such as WebServer which has an attribute that is a
> list of all documents associated with this web server (e.g. /index.html,
> /foo/bar.html, etc.) what happens when I retrieve a particular WebServer
> object from the Ozone database?
> - Does this list of web documents also get loaded? That would be a problem
> as the list could be quite large and loading it would require lots of RAM).
the list structure gets loaded but not the actual entries.
> - If, in this case, the whole list would get loaded, how do you suggest I
> design this in order to minimize redundancy and memory consumption?
if even the list itself is to big to fit into main memory than you need to come
up with some kind of lazy ozone collection (list). The DxDiskHashmap does
exactly this but it cannot be used for ozone apps out-of-the-box (it written to
be used inside the ozone kernel) but it might be a good starting point.
>
> 3. How does one retrieve a specific object from an Ozone database?
> For example, say that my objects stored in Ozone DB have a 'creationDate' attribute and a method such as this:
> public Date getCreationDate();
>
> How would I go about retrieving the object with the oldest creationDate attribute?
>
> Also, is it possible to retrieve an object or a set of objects based on the exact attribute value (e.g. all cars made in 1974)?
>
> Similarly, is it possible to retrieve an object or a set of objects bases on the range of values (e.g. all cars made between 1974 and 1984)?
There is no descriptive query system yet. There are two possibilities: 1) your
queries are not that complex; in this case you can Java-code the queries. 2)
the queries are complex; in this case you can start an effort to finally make a
descriptive query system for ozone ;)
Falko
>
> Thank you,
>
> Otis
>
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______________________________________________________________________
Falko Braeutigam mailto:falko@smb-tec.com
SMB GmbH http://www.smb-tec.com
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