XML query engines: was RE: Is XML dead already or what?
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.
Digital Logikk AS
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