Supporting complex queries on multiversion XML documents

Abstract

Managing multiple versions of XML documents represents a critical requirement for many applications. Recently, there has been much work on supporting complex queries on XML data (e.g., regular path expressions, structural projections, etc.). In this article, we examine the problem of implementing efficiently such complex queries on multiversion XML documents. Our approach relies on a numbering scheme, whereby durable node numbers (DNNs) are used to preserve the order among the nodes of the XML tree while remaining invariant with respect to updates. Using the document's DNNs, we show that many complex queries are reduced to combinations of range version retrieval queries. We thus examine three alternative storage organizations/indexing schemes to efficiently evaluate range version retrieval queries in this environment. A thorough performance analysis is then presented to reveal the advantages of each scheme.

DeltaNI

“…This relocation is simply accomplished by a swap of the range R 2 = [3, 6] (all bounds of the subtree C) and R 3 = [7,9] (all bounds between the subtree and the target position). The ranges R 1 = [0, 3] and R 4 = [10, ∞] do not take part in the swap and are not altered.…”

“…The dashes around F depict that it is outside of the active region. Again, this insertion is accomplished by swapping regions R 2 = [6,9] and R3 = [10,11] and incrementing the max value of the resulting version by +2 because a new node was added to the active region. The right side of the figure shows how F is deleted by swapping R 2 = [6,7] and R3 = [8,11] and reducing max.…”

“…The delta is inferred by inserting a range for the first column and for each other column in which the translation value is different to the value of the previous column (highlighted in the figure). Thus, the resulting delta for the target hierarchy in the middle contains the four translation ranges {R(0, 0), R(4, 6), R(7, 4), R (9,9)}. The right side of the figure shows a target hierarchy where more changes were introduced.…”

Towards a general entity representation model

“…Various techniques that employ different strategies have been proposed for efficiently storing different versions of data objects [4,5]. Versioning has also been studied in the context of semi-structured documents [6], and efficient query answering algorithms have been proposed [7]. When entities are created and modified, we are interested in keeping track of information related to the provenance of the entity data stored in the repository [8].…”

Entity Data Management in OKKAM

“…Various techniques that employ different strategies have been proposed for efficiently storing different versions of data objects [24] [25]. Versioning has also been studied in the context of semi-structured documents [26], and efficient query answering algorithms have been proposed [27].…”