Cal,
Cal Evans wrote:
>
> Glorious Sunday morning greetings to you Jan,
>
> No, XML is a format for 2 different applications, usually 2 totally separate
> applications, to be able to exchange data.
> It is not an appropriate choice
> for storing large amounts of data that will have to be queried.
But the XML markup is just a manifestation of a deeper structure: trees.
Trees are more general than tuples, a piece of XML can convey more information
than a piece of a relational table.
> Nor is it an appropriate choice of language for talking to an RDBMS.
> Outside of the fact that it can be extremely verbose,
...it compresses magnificiently...
> we already have a perfectly good language for that, SQL.
> SQL is a language for committing data to a storage mechanism
> and retrieving the data back. It is superior to XML in those tasks.
No.
SQL is limited by the linear structure of tables.
If you need to retrieve/store more complex information,
you need to place several SELECTs/INSERTs in a row.
Compare this to the rich structure of trees XML is based on.
I know I can represent a Request for Quote in one XML document,
but the same thing would take me five tables of a relational database.
I know I can represent a Quote - which is a result of the Request for Quote query -
with just one XML document, while the same thing would take me at least four
relational tables.
> Again, if you have need to talk to your RDBMS via XML then a thin wrapper
> written in the language of your choice is the proper way to go. This allows
> you to do your job without bloating my application with unnecessary code.
I'm already tired of thin wrappers.
Plus they are not exactly efficient; the two overheads are in place and hogging:
1. The client/server communication overhead, even if we go locally thru a socket;
2. The SQL overhead of having to parse, understand and optimize a query can kill you
on thousands of
queries.
As a rule, new functionalities in MySQL are optional.
You don't have to enable them.
> And I also disagree with your statement that there is no difference between
> metadata and data. there most certainly is. But that's a discussion for
> another thread.
It's always data.
You call it metadata if it describes some other data.
But on its own, it's data in the first place.
> humbly,
> Cal
> http://www.calevans.com
Yours,
Jan
> p.s. another reason not to include it is NOBODY wants to distract the MySQL
> coders from getting 4.0 frozen and out the door! :)
Hey, eventually a good reason against XML in MySQL!
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Jan Dvorak
> Sent: Sunday, February 25, 2001 10:13 AM
> To: Ed Carp
> Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]
> Subject: Re: XML support under mySQL
>
> Ed Carp wrote:
> >
> > Gorjan Todorovski ([EMAIL PROTECTED]) writes:
> >
> > > Since XML is a way to exchange data...and it is protocol/platform
> indepdnent
> > > there is a very good reason to have XML docuemts going in and out the
> >
> > No, it's not. You store *data* in a database, *not* metadata. Do you
> understand the difference?
>
> There is no difference.
> What is metadata in one context, is data in another context.
> It's just a matter of your standpoint, which can change with time.
>
> XML is a format to store/exchange data.
>
> Jan Dvorak
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