Journal of Applied Sciences1812-56541812-5662Asian Network for Scientific Information10.3923/jas.2007.2934.2946HawSu-Cheng LeeChien-Sing 122007720As XML (eXtensible Mark-up Language) is gaining its popularity in data exchange over the Web, querying XML data has become an important issue to be addressed. In native XML databases (NXD), XML documents are usually modeled as trees and XML queries are typically specified in path expression. The primitive structural relationships are Parent-Child (P-C), Ancestor-Descendant (A-D), sibling and ordered query. Thus, a suitable and compact labeling scheme is crucial to identify these relationships and henceforth to process the query efficiently. We propose a novel labeling scheme consisting of < self-level:parent> to support all these relationships efficiently. Besides, we adopt the decomposition-matching-merging approach for structural query processing and propose a hybrid query optimization technique, TwigINLAB to process and optimize the twig query evaluation. Experimental results indicate that TwigINLAB can process all types of XML queries 15% better than the TwigStack algorithm in terms of execution time in most test cases.]]>Abiteboul, S., D. Quass, J. McHugh, J. Widom and J.L. Wiener,199716888Abraham, J., N.S. Chaudhari and E.C. Prakash,20042004pp: 286289Chien, S.Y., Z. Vagena and D. Zhang,20022002pp: 141152Amer-Yahia, S., S. Cho, L.V.S. Lakshmanan and D. Srivastava,200211315331Brantner, M., S. Helmer, C.C. Kanne and G. Moerkotte,20052005pp: 705716Bruno, N., D. Srivastava and N. Koudas,20022002pp: 310321Chen, Q., A. Lim, K. Ong and J. Tang,20032003pp: 134144Christophides, V., S. Cluet and J. Simeon,20002000pp: 141152Chung, CW., J.K. Min and K. Shim, 20022002pp: 121132Cohen, E., H. Kaplan and T. Milo,20022002pp: 271281Cooper, B.F., N. Sample, M.J. Franklin, G.R. Hjaltason and M. Shadmon,20012001pp: 341350Dietz, P.F.,198221122127El-Sayed, M., K. Dimitrova and E.A. Rundensteiner,20032003pp: 147154Frasincar, F., G. Houben and C. Pau,2002244956Galanis, L., E. Viglas, D.J. DeWitt, J.F. Naughton and D. Maier,20022002Goldman, R. and J. Widom, 19971997pp: 436445Haw, S.C. and G.S.V.R.K. Rao,2005297104Haw, S.C. and G.S.V.R.K. Rao,200728287He, H. and J. Yang,20042004pp: 683694Jagadish, H., L. Lakshmanan, D. Srivastava and K. Thompson,20012001pp: 149164Jiang, H., W. Wang, H. Lu and J.X. Yu,20032003pp: 273284Jiang, H., H. Lu and W. Wang,20042004pp: 5970Jiao, E., T.W. Ling, C.Y. Chan and S. Yu,20052005pp: 113124Josifovski, V., M. Fontoura and A. Barta,200514197210Kanne, C.C., M. Brantner and G. Moerkotte,20052005pp: 742753Kaushik, R., D. Shenoy, P. Bohannon and E. Gudes,20022002pp: 129140Kaushik, R., P. Bohannon, J.F. Naughton and H.F. Korth,20022002pp: 133144Kim, J., S.H. Lee and H-J. Kim,2004916975Kimber, W.E.,19931993Li, Q. and B. Moon,20012001pp: 361370Lu, J., T. Chen and T.W. Ling,20042004pp: 533542McHugh, J. and J. Widom,19991999pp: 315326Milo, T. and D. Suciu,19991999pp: 277295O'Neil, P., E. O'Neil, S. Pal, I. Cseri, G. Schaller and N. Westbury,20042004pp: 903908Polyzotis, N., M. Garofalakis and Y. Ioannidis,20042004pp: 263274Tatarinov, I., S. Viglas, K.S. Beyer, J. Shanmugasundaram, E.J. Shekita and C. Zhang,20022002pp: 204215Viglas, S.D., L. Galanis, D.J. DeWitt, D. Maier and J.F. Naughton,20022002Weigel, F., K.U. Schulz and H. Meuss,20052005pp: 4967Wu, X., M.L. Lee and W. Hsu,20042004pp: 6678Wu, Y., J.M. Patel and H. V.Jagadish, 20032003pp: 443454Yao, J.T. and M. Zhang,20042004pp: 235241Yu, T., T.W. Ling and J. Lu,20062006pp: 249263Zezula, P., F. Mandreoli and R. Martoglia,20042004pp: 122139Zhang, D. and Y. Dong,19991999pp: 711714Zhang, C., J. Naughton, D. DeWitty, Q. Luo and G. Lohman,200130425436Zhang, N.,20062006Zheng, S., A. Zhou, J.X. Yu, L. Zhang and H. Tao,20022002pp: 2536