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Enumerating XML Data for Dynamic Updating L.Kit and V.Ng, Hong Kong Polytechnique University

Enumerating XML Data for Dynamic Updating L.Kit and V.Ng, Hong Kong Polytechnique University. Sang-Ho Nah Lily Daniel Yun Hee Lee. Introduction. n-Inode: new model-mapping approach Multidimensional node ID for indexing and node-to-node relationship calculation

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Enumerating XML Data for Dynamic Updating L.Kit and V.Ng, Hong Kong Polytechnique University

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  1. Enumerating XML Data for Dynamic UpdatingL.Kit and V.Ng, Hong Kong Polytechnique University Sang-Ho Nah Lily Daniel Yun Hee Lee

  2. Introduction • n-Inode: new model-mapping approach • Multidimensional node ID for indexing and node-to-node relationship calculation • Supports dynamic updating of XML data flexibly

  3. n-INode • XML document represented as nc-ary complete tree, where nc=maximum number of child node per node • Multidimensional node ID: k-dimensional ID:(id1, io1, id2, io2, …, idk, iok) idx: Node identifier assigned by numbering scheme iox: Insertion order, sequential number starting from 0 • Presence of iox allows more than nc child nodes to be inserted. No re-calculation of existing nodes’ id required

  4. n-INode cont • Insertion Rules • If newly inserted node’s id1 exists in the tree, its io1 is incremented from maximum io1 among existing nodes with the same id1 • If new node is inserted to the “right most position”, and maximum io1 (of all the nodes with the same id1) is less than nc, then io1 = nc+1 • A new dimension is introduced to all descendants of a node that has io1 > 0. Parent’s first dimension is assigned to the child’s first dimension.

  5. n-INode cont • Parent-Child relationship: • Pair of nodes with the same number of dimensions • Pair of nodes with dimensional difference of one • Parent and Child MUST share the identical first dimension • Ancestor-Descendant relationship: • Above 2 situations • Pair of nodes with dimensional difference of more than one

  6. Implementation & Experiment • Required storage space is not the smallest of all the models tested • Other test results show that this is a reasonable trade-off • Query time is reasonable and consistent – shows it does not depend heavily on the type of query

  7. Possible flaws in n-INode • Node relationship calculation/verification rule excludes a case where both nodes in the pair have 1-dimensional ID (first dimensions cannot be the same) • Path sequence of each node changes by allowing more than nc child nodes to be inserted – therefore path sequence should not be used in node identifier calculation

  8. Conclusion • Identifying the insertion order removes restriction on the number of child nodes to be inserted • Re-calculation of existing nodes’ ID is not required • This allows for more effective and efficient node locating operation, supporting dynamic updates of XML data. • However, some aspects were overlooked and this makes the proof of correctness presented in the paper somewhat deficient.

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