[Monetdb-developers] Is monetDB nativeXML or not?

Lefteris lsidir at gmail.com
Fri Jul 10 09:51:19 CEST 2009


Hi,

this is a big issue. I generally do not agree with the definition of
native. However, for the general accepted terminology MonetDB/XQuery
is *not* a native XML database. We map XML documents to a relational
representation. Please see the paper:  MonetDB/XQuery: A Fast XQuery
Processor Powered by a Relational Engine
(http://www.cwi.nl/htbin/ins1/publications?request=pdf&key=BoGrKeMaRiTe:SIGMOD:06)

The reason that I don't agree with the definition is that native has
nothing to do with the physical representation. Monet stores data in
arrays, and  arrays are the simplest structures that a computer
understands (we could say the native structure of a CPU). Any native
XML database eventually will store its data to arrays too. So the
statement "... uses XML documents as the fundamental unit of storage"
is kinda of weird because XML is not even a "unit of storage". Native
is about the optimizer, the algebra and the logical level of the DBMS.

lefteris

On Fri, Jul 10, 2009 at 9:05 AM, Mtekel<thx at trolej.sk> wrote:
> Hello,
>
> I have a question, whether MonetDB/XQuery is native XML database or not.
> To clarify what is native or not, http://en.wikipedia.org/wiki/XML_database
> : "
>
> Two major classes of XML database exist:
> XML-enabled: these map all XML to a traditional database (such as a
> relational database), accepting XML as input and rendering XML as output.
> This term implies that the database does the conversion itself (as opposed
> to relying on middleware).
> Native XML (NXD): the internal model of such databases depends on XML and
> uses XML documents as the fundamental unit of storage, which are, however,
> not necessarily stored in the form of text files.
>
> "
>
> Then according to this page, monetDB is native XML:
> http://monetdb.cwi.nl/MonetDB/Version4/Documentation/monet/index.html
>
> "
> 2 MonetDB Features
>
> MonetDB is database engine geared at high performance on systems with
> (complex) queries that have to analyze large amounts of data (i.e. OLAP, not
> OLTP). The features in which it most differs from other DBMSs are summarized
> below:
> Independence of SQL:
>
> MonetDB has a front-end/back-end design allowing the storage of more than
> just relational tables (such as object-oriented or native XML data), and
> allowing the use of querying paradigms other than just SQL (such as OQL and
> XQuery).
>
> "
>
> Whereas according to this one, it is not:
> http://monetdb.cwi.nl/projects/monetdb/XQuery/Documentation/Separate-Documen
> ts-vs-Document-Collections.html#Separate-Documents-vs-Document-Collections :
> "
> 2.9.1.1 Storage Overhead
>
> In MonetDB/XQuery all XML is stored in relational tables.
> "
>
> Is then monetDB really native?
>
> Thanks in advance for clarification...
>
> Regards,
>
> M. Tekel
>
>
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