Research On Improved Fractional Encoding Scheme Based On Update Identifier

Nowadays, XML has become an important standard for data storage, representation and exchange on the Web. XML has many advantages, such as scalability, openness, high compression rate and ability to ensure the structural integrity of the data, etc. But at the same time, it also has many disadvantages, such as redundant information, multi-branch structure and so on. How to effectively manage XML data has become a hot topic of XML technology research. Therefore, the scholars made a number of particular XML data encoding scheme which greatly improved encoding and management efficiency of XML data. However, these encoding scheme have some weakness, such as the efficiency of the query is low, and when XML nodes is frequently and substantially updating, we need to re-encoding which is a huge cost. This paper carried out the relevant aspects of the research.In this paper, XML document encoding technology has been thoroughly analyzed, and proposed an improved fraction encoding scheme which based on the update identifier(UIFES). UIFES breaks down information of nodes and paths, and puts these information into corresponding tables to avoid recording repeated information, so as to save storage space; Meanwhile the encoding scheme saves every node path in the path information table, and finds the location of the node by the path number in the query. And in doing so, we avoid the structure connection operation for the existing query algorithm. Moreover, the length of path expression and the scale of intermediate result set could not influence the query. So the efficiency of the query has been greatly improved. Finally UIFES takes advantage of the FraCode and the UICode to solve the problem of insufficient space, and avoid re-encoding in some special cases, the updating cost is very small. So it can greatly improves the efficiency of the node updating.In conclusion, the main work of this paper is as follows:(1) This paper carefully analyzed the existing XML data encoding scheme and pointed out the advantages and disadvantages of those schemes.(2) This paper proposed a new encoding scheme which is also called UIFES. The encoding scheme fully combined the advantages of fraction encoding and prefix encoding. It not only can effectively support the dynamic update of nodes, but also has high query efficiency. UIFES has higher efficiency of querying compared than prefix encoding, and spends less time in inserting new nodes compared than fraction encoding.(3) The related definitions and algorithms for the proposed encoding scheme are explained in detail in this paper. The characteristics of the encoding scheme were introduced. The updating and querying algorithm was proposed, and the encoding update details after inserting new nodes are explained by some examples. This paper also described the query process in detail.(4) Through experiments, UIFES is analyzed and compared with the control group encoding schemes in the following aspects: time performance, dynamic update performance, and query performance. It verifies the validity of UIFES.Experimental results show that in comparison with the existing encoding schemes, UIFES has better performance in the encoding, updating and querying efficiency.