Subject: unQL(makoto)
From: Ayako Onizuka (oni@mbe.sphere.ne.jp)
Date: Mon Apr 09 2001 - 11:54:02 PDT
= title =
UnQL: A query language and algebra for semistructed data
based on structural recursion
= summary and key idea =
This paper describes about UnQL that based on Structural recursion.
Basic concept are:
- Data model is semi-strucured data model.
The model is value-based that suits to skolem function.
- Query algebra is based on recursive functions.
Some restrictions ensures determinism and temination.
- SQL-like query language
- Translation from both query and path exression to structural recursion
- It is possible to re-write query or combine view and query expression.
= question =
- Are the restriction too strong to ensure determinism and temination?
- What is the advantage of using structural recursion?
To ensure determinism and temination?
Or structural recursion suits to semi-structured data?
Or input data can be processed in to-down manner?
- Why "to some extent XSL can serve as a limited query language?"
I think XSL has much functionality for querying and transformation,
even though XSLT expression is not easy to understand and XPath has
some fault.
- Why document() function is not enough for join operation?
I think document() function is better than a operation like cartesian
product.
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