ali mohammad wrote:
At the risk of slightly sounding off topic (but it does base on
Kenneth's question on specific examples), I would like anybody's views
on the applicability of XML database to clinical databases where the
information that needs to be stored comes from a domain that is largely
undefined or unpredictable in advance (maybe the more precise term is
unstructured data but I am not too sure as I am amateur programmer
myself). I did have in the past developed clinical databases (data
captured from clinical trials) using the EAV model out of relational
tables. The queries turned out to be terribly slow so I was forced to
used a combination of true relational tables and EAV tables out of
hacked up relational tables. Even then, the performance levels sucked.
If you're going to do EAV, you need an EAV database. While you can
theoretically store anything in tables, if you insist on pounding EAV
triangles into rectangular SQL holes, performance will be abysmal, as
you noticed. The EAV model fits some medical applications very well, but
you really do need a database designed for that use case.
XML is seeing extensive uptake in the healthcare industry, though I'm
not personally aware of any applications that use an XML database (yet).
That may just be a matter of time. The key differences that might
suggest using an XML database for medical data are:
1. No predefined schemas is required. You're always free to add new
information as it comes to light.
2. Null data doesn't take up any space. You simply leave it out.
These are also characteristics that EAV databases share relative to SQL
databases. Whether XML databases may have other characteristics that
make them inferior or superior to EVA databases for medical apps, I
don't know.
P.S. By "medical apps" I'm referring to ones that include diagnoses,
treatments, and the practice of medicine. Medical billing, patient
management, and so forth isn't all that different from other business
applications. Those sorts of applications do perform reasonably well in
a relational database.
--
Elliotte Rusty Harold [EMAIL PROTECTED]
Java I/O 2nd Edition Just Published!
http://www.cafeaulait.org/books/javaio2/
http://www.amazon.com/exec/obidos/ISBN=0596527500/ref=nosim/cafeaulaitA/
_______________________________________________
New York PHP Community Talk Mailing List
http://lists.nyphp.org/mailman/listinfo/talk
NYPHPCon 2006 Presentations Online
http://www.nyphpcon.com
Show Your Participation in New York PHP
http://www.nyphp.org/show_participation.php
