Issues in XML Compression Compression ratios Compression time Query coverage. memory Usage ...(see my survey paper in wwwJ) Technologies Compression Compression Memory Usage Time Compression Used (compared(compared( for compression Scheme with Gzip) with Gzip) Used Consistently Constant Not Support SAX Better Slower 8 MB (default) Querying Compress (UNIX) Much At least two Roughly Huffman Exact-match, SAX times longer Constant Coding Prefix-match Xpath Axes Child Attribute XPRESS At least two Roughly uffman Coding, Exact-match, SAX Constant Approximated Prefix-match Xpath Axes Arithmetic Child and Encoding Descendant Attribute prohibitively Constant onge XMLZip Comparable Much Proportional Not Support DOM Querying Input Data Size porti tructure Better Longer Io Compression Querying Slightl Much Proportional Differential Not Support DOM DDT Better DTD Tree Querying Input Data Size Compression, Comparison of existing technologies6 Issues in XML Compression ▪ Compression ratios, Compression time, Query Coverage, Memory Usage…(see my survey paper in WWWJ) Comparison of existing technologies