Re: [xml-dev] Shredding XML

["David A. Lee" <dlee@calldei.com>]

Ron Bourret has some excellent references here
http://www.rpbourret.com/xml/XMLDBLinks.htm#Relational

I took a 1 day class from him years ago in which he covered the topic 
very well.
I suggest its too big a topic for an email discussion.

I've been faced with this problem myself on multiple occasions where the 
organization is not very XML friendly and "needs" the data in a 
relational DB and inevitably the solution has been

1) Dont do it.
--> XML ended up in files , sometimes a DB table with top level topics 
or some basic metadata only.

2) Put XML in "Blob" fields
--> solves the "letter of the law" -- yea its in "A Relational Database" 
but its useless

3) Its a royal PITA
A shredding can end up with about 2x the # of distinct elements into 
tables.   Handling mixed content is excruciatingly painful.
Doing a good job usually ends up with relational data thats almost 
impossible to access relationally.


But it all really depends on how complicated your XML is.   If its dirt 
simple XML then shredding it may work fine for you.



David A. Lee
dlee@calldei.com  
http://www.calldei.com
http://www.xmlsh.org
812-482-5224



Fraser Goffin wrote:
> This list has been unusually quiet of late so I thought it might be an
> opportune moment to ask for opinions on the subject of decomposing XML
> into relational databases, often referred to as 'shredding'.
>
> My particular interest is related to some work I'm currently engaged
> in. The basics are we receive XML messages from an external trading
> partner and process those messages, enriching and routing to a number
> of internal subscriber applications. One of these applications is MI
> and the deal here is that they want the data to been put into a
> relational database so that they can create a number of interfaces
> 'files' which are sent to still more applications.
>
> Whilst I would like to consider a pure XML database or even use some
> of the XML features that are increasingly prevalent in mainstream DB
> vendor products, clearly putting data into a 'staging' database is one
> thing, but the capabilities and competances of the applications and
> application programmers who want to retrieve it is a key factor. So,
> for the immediate term I might be stuck (if thats fair - probably not)
> with relational.
>
> So to better inform myself and maybe help the debate along internally,
> I am interested in anyone else experience good and bad, of shredding
> XML data, pitfalls, things to be aware of, good approaches, when to
> really not do it. All thoughts are welcome.
>
> I find it intersting the some of the 'big boys' are at least giving
> the appearance of providing first-class support for XML both in terms
> of storage options and manipulation capability. IBM for example has
> pureXML. I haven't used these enough to know if they're just a thin
> veneer of whether they have real substance and depth, so again your
> experiences are welcome.
>
> Regards
>
> Fraser,
>
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