Query evaluation in an XML database requires reconstructing XML subtrees
rooted at nodes found by an XML query. Since XML subtree reconstruction can be
expensive, one approach to improve query response time is to use reconstruction
views - materialized XML subtrees of an XML document, whose nodes are
frequently accessed by XML queries. For this approach to be efficient, the
principal requirement is a framework for view selection. In this work, we are
the first to formalize and study the problem of XML reconstruction view
selection. The input is a tree T, in which every node i has a size ciβ
and profit piβ, and the size limitation C. The target is to find a subset
of subtrees rooted at nodes i1β,β―,ikβ respectively such that
ci1ββ+β―+cikβββ€C, and pi1ββ+β―+pikββ is maximal.
Furthermore, there is no overlap between any two subtrees selected in the
solution. We prove that this problem is NP-hard and present a fully
polynomial-time approximation scheme (FPTAS) as a solution