Efficient Processing Of Temporal XML Using The Structural Summary Style Method

As the development of computer technology and network technology, XML (Extensible Markup Language) has recently emerged as a new standard for data representation and exchange on the Internet. It is expected that XML will become a universal format for data exchange on the Web. Generally speaking, we make some changes on XML documents as time goes by. Then, we may want to query about past states of such documents. In such situations, the topic of representing temporal data, tracking historical information, and recovering the state of the document as of any given time, in XML documents has been receiving increasing attention.Indexing technique is significant for efficient XML (both temporal XML and non-temporal XML) data processing. In the researches of indexing non-temporal XML field, many types of indexes have been proposed. And these can be classified into two categories, node-record-style index and structural-summary-style index. However, few studies have been reported on the issue of indexing temporal XML. Most of them create a new physical version each time an update occurs, leading to large overheads when processing temporal queries that span multiple versions. Meanwhile, because of containing of temporal information in XML documents, update of temporal XML documents are complex. This makes the index update much harder than non-temporal index. Obviously, the way of rebuilding the index and recoding the nodes is inefficient.This paper proposed a new temporal XML indexing method, TF&B index, based on the features of temporal XML documents. We introduce the index by the structure, query algorithms and update algorithms.The main works and achievements of this paper are:1. It proposes the index structure of TF&B index in detail, and gives the creation algorithms2. It divides the temporal XML query expressions into four types, and gives the experiments data. Through the results, we can see this TF&B index has better performance than the indexes proposed before.3. It discusses the insert, delete and update of the temporal XML documents, and proposes the TF&B incremental update algorithms.The contribution of this paper is that it creates an effective system of indexing temporal XML, TF&B index: in the design of Temporal XML document model, it only saves the relationships among different nodes in any give time, rather than the snapshot of the document, which sovles the problem of scanning the data that span multiple versions; in the coding of nodes, it utilizes the extended preorder numbering scheme, so that when update occurs, recoding the nodes is not needed. In the design of query algorithms, it reduces tree travels and disk accessing times by keeping a summary of the documents and employing several clustering criteria. In the design of update algorithms, it avoids the index rebuilding by using incremental ways.