Re: XMLType performance

On Apr 11, 8:27 pm, Serge Rielau <srie..._at_ca.ibm.com> wrote:
> DA Morgan wrote:
> > The Geek Inside wrote:
> >> Hello there,
>
> >> I'm involved in a project with many XML managment and I'm evaluating
> >> using the XMLType to store several information types in XML structures
> >> and extract information from these.
>
> >> This is the first time using XMLType, I would like to get some
> >> feedback about the preformance using XMLType.
>
> >> The system will have many queries to this information.
>
> >> Thanks in advance.
>
> > I would never store XML inside a database if it could be reconstituted
> > on demand.
>
> > Without knowing the full set of requirements my initial reaction would
> > be ... never store XML.
>
> > Consider the scability and storage of:
> > <thisisareallylongtag>1</thisisareallylongtab>
> > To which you can add the lack of relational integrity.
>
> When a schema is highly volatile, e.g. tax-return forms, XML beats
> relational hands down. Tables are so...square.
> Also XML documents can contain electronic signatures. Shredding and
> reconstitution can cause serious headache to that end.
> What I see is that XML is stored in the database, but the core reference
> attributes are pulled out into regular column for quick processing
> (and RI enforcement, ..).
>
> The right tool for the right job.

I don't see that in the OP. I read it as many queries extracting from the XML. Of course, I may be reading it wrong.

I see your statement as supporting the idea that information needs to be taken out of the XML for quick processing. So I think we agree. But of course I may be reading your comment wrong too.

Now, Daniel says never store XML in the DB, and I think your tax example is perhaps a good refutation of that. The IRS stores each data element with an XML tag (see http://www.irs.gov/efile/article/0,,id=146364,00.html ) The stuff I'm working on, on the other hand, is transactional data being stored as XML. _That's_ what I'm calling stupid, and we would need more info to know if that is what the OP is contemplating. Then again, if I had the IRS's resources, maybe I wouldn't consider it so bad.

(A clip from when I posted about it on a blog: "Of course, right now I'm trying to reconcile some "sophisticated" XML product with an Oracle relational database, and wondering how an Oracle DBA might have had input to it, and I just don't see any way. The XML seems to have this idea of shipping the metadata with the data, so you wind up with metadata that says nothing about anything to contain metadata within the data, and tables with fields to contain the metadata translations to the relational db and metadata about the transaction (much of which came from the Oracle db!) and all the data in varchar2(4000) with the occasional funny character. Or something like that. If it works, who am I to complain?")

jg

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