On supporting containment queries in relational database management systems
SIGMOD '01 Proceedings of the 2001 ACM SIGMOD international conference on Management of data
Storing and querying ordered XML using a relational database system
Proceedings of the 2002 ACM SIGMOD international conference on Management of data
QED: a novel quaternary encoding to completely avoid re-labeling in XML updates
Proceedings of the 14th ACM international conference on Information and knowledge management
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The basic relationships to be determined in XML query processing are ancestor-descendant (A-D), parent-child (P-C), sibling and ordering relationships. The containment labeling scheme can determine the A-D, P-C and ordering relationships fast, but it is very expensive in determining the sibling relationship. The prefix labeling scheme can determine all the four basic relationships fast if the XML tree is shallow. However, if the XML tree is deep, the prefix scheme is inefficient since the prefix is long. Furthermore, the prefix label is repeated by all the siblings (only the self labels of these siblings are different). Thus in this paper, we propose the P-Containment and P-Prefix schemes which can determine all the four basic relationships faster no matter what the XML structure is; meanwhile P-Prefix can reduce the redundancies in the prefix labeling scheme.