XML-Specific Compressors Unqueriable Compression( e.g. XMill) Full-chunked data commonalities eliminated Very good compression ratio Queriable Compression(e.g XGrind, XPRESS Fine-grained: data commonalities ignored Inadequate compression ratio and time Support simple path queries with atomic predicate5 XML-Specific Compressors ▪ Unqueriable Compression (e.g. XMill): • Full-chunked: data commonalities eliminated • Very good compression ratio ▪ Queriable Compression (e.g. XGrind, XPRESS): • Fine-grained: data commonalities ignored • Inadequate compression ratio and time • Support simple path queries with atomic predicate