XML Retrieval Using Pruned Element-Index Files

Abstract

Abstract. An element-index is a crucial mechanism for supporting content-only (CO) queries over XML collections. A full element-index that indexes each element along with the content of its descendants involves a high redundancy and reduces query processing efficiency. A direct index, on the other hand, only indexes the content that is directly under each element and disregards the descendants. This results in a smaller index, but possibly in return to some reduction in system effectiveness. In this paper, we propose using static index pruning techniques for obtaining more compact index files that can still result in comparable retrieval performance to that of a full index. We also compare the retrieval performance of these pruning based approaches to some other strategies that make use of a direct element-index. Our experiments conducted along with the lines of INEX evaluation framework reveal that pruned index files yield comparable to or even better retrieval performance than the full index and direct index, for several tasks in the ad hoc track.

Focused Retrieval and Evaluation

“…For the pruning levels higher than 70%, DCP and TCP give better results interchangeably for these measures. In [1], we observed a similar behavior regarding the retrieval effectiveness of indexes pruned with TCP and DCP.…”

“…From the previous works, it is known that static index pruning techniques can reduce the size of an index (and the underlying collection) while providing comparative effectiveness performance with that of the unpruned case [2,3,4,5,8]. In a more recent study, we show that such pruning techniques can also be adapted for pruning the element-index for an XML collection [1]. Here, with the aim of both improving the quality of clusters and reducing the dataset dimensions for clustering, we apply static pruning techniques on XML documents.…”

Exploiting Index Pruning Methods for Clustering XML Collections

“…For the pruning levels higher than 70%, DCP and TCP give better results interchangeably for these measures. In [1], we observed a similar behavior regarding the retrieval effectiveness of indexes pruned with TCP and DCP. From Table 3, we also deduce that DCP-based clustering at 30% pruning level produce the best results for both of the evaluation measures in comparison to the other pruning-based clusters.…”

“…In a more recent study, we show that such pruning techniques can also be adapted for pruning the element-index for an XML collection [1]. Here, with the aim of both improving the quality of clusters and reducing the dataset dimensions for clustering, we apply static pruning techniques on XML documents.…”