XML query engines: was RE: Is XML dead already or what?

Jarle Stabell jarle.stabell at dokpro.uio.no
Sun Jan 31 19:45:19 GMT 1999

Borden, Jonathan  wrote:

> 	The problem with a straight relational approach is that we need to model
> containment and heirarchies... in SQL terms this means joins, perhaps
> multilevel joins when documents are deep.

There exists a neat trick which enables simple SQL-Select queries answering 
for two given nodes, whether one is a subnode of the other, and also how 
many levels deep, in constant time, assuming you do some simple 
preprocessing on the structure. (Assigning two integers to each node in the 

I don't know who "invented" this trick, but I know that Joe Celko has 
written about it, perhaps he first described it.


Jarle Stabell
Digital Logikk AS

xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/
To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
(un)subscribe xml-dev
To subscribe to the digests, mailto:majordomo at ic.ac.uk the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)

More information about the Xml-dev mailing list