Date: 06 Jul 2001

View Maintenance for Hierarchical Semistructured Data

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The problem of incremental view maintenance in materialized data warehouses has been studied extensively for relational selectproject-join (SPJ) views. Many new data sources, however, are highly irregular and views often perform complex restructuring operations. This paper describes WHAX (Warehouse Architecture for XML), an architecture for defining and maintaining views over hierarchical semistructured data sources with key constraints. The WHAX model is a variant of the deterministic model [5], but is more reminiscent of XML. The view definition language is a variation of XML-QL and supports selections, joins, and important restructuring operations such as regrouping and aggregation. The incremental maintenance is based on the notion of multi-linearity and generalizes well-known techniques from SPJ-views.

This research was supported in part by DOE DE-FG02-94-ER-61923 Sub 1, NSF DBI99-75206, NSF IIS98-17444, ARO DAAG55-98-1-0331, and a grant from SmithKline Beecham.