10807744
XML Query Processing and Optimization
In this paper, I summarize my research on optimizing XML queries This work has two components: the first component is the definition of a logical algebra and logical optimization techniques This algebra can be translated into different physical algebras such as native or extended-relational algebras The second component is the design of physical storage structures and physical optimization techniques.
17853419
A succinct physical storage scheme for efficient evaluation of path queries in XML
Path expressions are ubiquitous in XML processing languages. Existing approaches evaluate a path expression by selecting nodes that satisfies the tag-name and value constraints and then joining them according to the structural constraints. We propose a novel approach, next-of-kin (NoK) pattern matching, to speed up the node-selection step, and to reduce the join size significantly in the second step. To efficiently perform NoK pattern matching, we also propose a succinct XML physical storage scheme that is adaptive to updates and streaming XML as well. Our performance results demonstrate that the proposed storage scheme and path evaluation algorithm is highly efficient and outperforms the other tested systems in most cases.
3386880
Statistical Learning Techniques for Costing XML Queries
Developing cost models for query optimization is significantly harder for XML queries than for traditional relational queries. The reason is that XML query operators are much more complex than relational operators such as table scans and joins. In this paper, we propose a new approach, called COMET, to modeling the cost of XML operators; to our knowledge, COMET is the first method ever proposed for addressing the XML query costing problem. As in relational cost estimation, COMET exploits a set of system catalog statistics that summarizes the XML data; the set of "simple path" statistics that we propose is new, and is well suited to the XML setting. Unlike the traditional approach, COMET uses a new statistical learning technique called "transform regression" instead of detailed analytical models to predict the overall cost. Besides rendering the cost estimation problem tractable for XML queries, COMET has the further advantage of enabling the query optimizer to be self-tuning, automatically adapting to changes over time in the query workload and in the system environment. We demonstrate COMET's feasibility by developing a cost model for the recently proposed XNAV navigational operator. Empirical studies with synthetic, benchmark, and real-world data sets show that COMET can quickly obtain accurate cost estimates for a variety of XML queries and data sets.
5525123
FIX: feature-based indexing technique for XML documents
Indexing large XML databases is crucial for efficient evaluation of XML twig queries. In this paper, we propose a feature-based indexing technique, called FIX, based on spectral graph theory. The basic idea is that for each twig pattern in a collection of XML documents, we calculate a vector of features based on its structural properties. These features are used as keys for the patterns and stored in a B+tree. Given an XPath query, its feature vector is first calculated and looked up in the index. Then a further refinement phase is performed to fetch the final results. We experimentally study the indexing technique over both synthetic and real data sets. Our experiments show that FIX provides great pruning power and could gain an order of magnitude performance improvement for many XPath queries over existing evaluation techniques.
35884730
Compact access control labeling for efficient secure XML query evaluation
Fine-grained access controls for XML define access privileges at the granularity of individual XML nodes. In this paper, we present a fine-grained access control mechanism for XML data. This mechanism exploits the structural locality of access rights as well as correlations among the access rights of different users to produce a compact physical encoding of the access control data. This encoding can be constructed using a single pass over a labeled XML database. It is block-oriented and suitable for use in secondary storage. We show how this access control mechanism can be integrated with a next-of-kin (NoK) XML query processor to provide efficient, secure query evaluation. The key idea is that the structural information of the nodes and their encoded access controls are stored together, allowing the access privileges to be checked efficiently. Our evaluation shows that the access control mechanism introduces little overhead into the query evaluation process.
5631107
Compact Access Control Labeling for Efficient Secure XML Query Evaluation
Fine-grained access controls for XML define access privileges at the granularity of individual XML nodes. In this paper, we present a fine-grained access control mechanism for XML data. This mechanism exploits the structural locality of access rights as well as correlations among the access rights of different users to produce a compact physical encoding of the access control data. This encoding can be constructed using a single pass over a labeled XML database. It is block-oriented and suitable for use in secondary storage. We show how this access control mechanism can be integrated with a next-of-kin (NoK) XML query processor to provide efficient, secure query evaluation. The key idea is that the structural information of the nodes and their encoded access controls are stored together so the access privileges can be checked efficiently. Our evaluation shows that the access control mechanism introduces little overhead into the query evaluation process.
13356041
Research on Distributed Data Mining Technology Based on Grid
Distributed data mining (DDM) techniques have become necessary for large and multi-scenario datasets requiring resources, which are heterogeneous and distributed. In this paper, we focused on distributed data mining based in grid. We have discussed and analyzed a new framework based on grid environments to execute new distributed data mining techniques on very large and distributed heterogeneous datasets. The architecture and motivation for the design have been presented. We pointed out that distributed data mining technology can offer a better solution since they are designed to work in a distributed environment by paying careful attention to the computing and communication resources.
7396264
Pseudo-Randomness of Discrete-Log Sequences from Elliptic Curves
We investigate an upper bound on the discrepancy and a lower bound on the linear complexity of a class of sequences, derived from elliptic curves by using discrete logarithm in this paper. The results indicate that these sequences may have `nice' pseudo-random properties. The important tool in the proof is certain character sums estimate along elliptic curves. In addition, we apply linear recurrence relation over elliptic curves to output binary sequences with very interesting pseudo-random behavior.
5143150
On Miquel's Five-Circle Theorem
Miquel's Five-Circle Theorem is difficult to prove algebraically. In this paper, the details of the first algebraic proof of this theorem is provided. The proof is based on conformal geometric algebra and its accompanying invariant algebra called null bracket algebra, and is the outcome of the powerful computational techniques of null bracket algebra embodying the novel idea breefs.
5856173
SHEETSPAIR: A Database of Amino Acid Pairs in Protein Sheet Structures
Within folded strands of a protein, amino acids (AAs) on every adjacent two strands form a pair of AAs. To explore the interactions between strands in a protein sheet structure, we have established an Internet-accessible relational database named SheetsPairs based on SQL Server 2000. The database has collected AAs pairs in proteins with detailed information. Furthermore, it utilizes a non-freetext database structure to store protein sequences and a specific database table with a unique number to store strands, which provides more searching options and rapid and accurate access to data queries. An IIS web server has been set up for data retrieval through a custom web interface, which enables complex data queries. Also searchable are parallel or anti-parallel folded strands and the list of strands in a specified protein.
10813806
An efficient protocol for anonymous and fair document exchange
Fairness in document exchange has been well studied, while anonymity in the exchange, which protects the privacy of personal information such as identities and locations, has been either ignored or handled with partial or inappropriate considerations. In this paper we propose a new protocol for anonymous and fair document exchange between two parties with the assistance of an off-line trusted third party. The new protocol treats both fairness and anonymity as essential properties, employs an efficient method for off-line key recovery, and places weak requirements on the security of the third party.