A Query about View Construction in XML

[Dong Hui Zhuo <dhzhuo@softbase.math.uwaterloo.ca>]

Hi,

I have a question about view construction in xml.

Problem Setting
===============
Given a XML database DB, and a query Q1, either XQuery or XSLT, we refer
to the result of Q1(DB) (the result of running query Q1 against database
DB) as a view, say V, whose schema is Sv.

Question
========
Suppose we have another query Q2 (either XQuery or XSLT) which is
formulated against schema Sv (the schema of the view V) and the
size of view V too big to fit in memory, my questions are:

1) Is it possible that we evaluate Q2(V), (that is running Q2 against the
result of Q1(DB)), without materializing (or write back to hard disk) the
result of Q1(DB)?

2) Does the answer depend on the type of query language, say XQuery or
XSLT? Does the answer depend on the implementation of specific query processor?

As we know, in relational database, Q2(V) can be evaluated without
materializing the view V. However, I am not sure if it is still hold in
XML database.

Thanks a lot

Terry