783838
Practical Indexing XML Document for Twig Query
Answering structural queries of XML with index is an important approach of efficient XML query processing. Among existing structural indexes for XML data, F&B index is the smallest index that can answer all branching queries. However, an F&B index for less regular XML data often contains a large number of index nodes, and hence a large amount of main memory. If the F&B index cannot be accommodated in the available memory, its performance will degrade significantly. This issue has practically limited wider application of the F&B index. 
 
In this paper, we propose a disk organization method for the F&B index which shift part of the leave nodes in the F&B index to the disk and organize them judiciously on the disk. Our method is based on the observation that the majority of the nodes in a F&B index is often the leaf nodes, yet their access frequencies are not high. 
 
We select some leaves to output to disk. With the support of reasonable storage structure in main memory and in disk, we design efficient query processing method). We further optimize the design of the F&B index based on the query workload. Experimental results verified the effectiveness of our proposed approach.
6238577
Labeling Scheme and Structural Joins for Graph-Structured XML Data
When XML documents are modeled as graphs, many challenging research issues arise. In particular, query processing for graph-structured XML data brings new challenges because traditional structural join methods cannot be directly applied. In this paper, we propose a labeling scheme for graph-structured XML data. With this labeling scheme, the reachability relationship of two nodes can be judged efficiently without accessing other nodes. Based on this labeling scheme, we design efficient structural join algorithms to evaluate reachability queries. Experiments show that our algorithms have high efficiency and good scalability.
2846401
Subgraph Join: Efficient Processing Subgraph Queries on Graph-Structured XML Document
The information in many applications can be naturally represented as graph-structured XML document. Structural query on graph structured XML document matches the subgraph of graph structured XML document on some given schema. The query processing of graph-structured XML document brings new challenges. 
 
In this paper, for the processing of subgraph query, we design a subgraph join algorithm based on reachability coding. Using efficient data structure, subgraph join algorithm can process subgraph query with various structures efficiently.
14161279
Database System Extensions for Decision Support: the AXL Approach
Research on database-centric data mining is seeking to improve the e ectiveness of database systems in decision support applications. Di erent solutions are now used for di erent problems, including (i) SQL extensions for more complex OLAP queries, (ii) new datablades for special data types such as time-series, and (iii) architectural extensions to support data mining functions. Here, we proposed a uni ed solution for all these problems; the solution is based on User-De ned Aggregates (UDAs) expressed in an SQL-like language called AXL. In this paper, we discuss the architecture and implementation of the AXL prototype and its use and performance in expressing data mining functions and complex OLAP queries.
9462787
XSeq: an indexing infrastructure for tree pattern queries
Given a tree-pattern query, most XML indexing approaches decompose it into multiple sub-queries, and then join their results to provide the answer to the original query. Join operations have been identified as the most time-consuming component in XML query processing. XSeq is a powerful XML indexing infrastructure which makes tree patterns a first class citizen in XML query processing. Unlike most indexing methods that directly manipulate tree structures, XSeq builds its indexing infrastructure on a much simpler data model: sequences. That is, we represent both XML data and XML queries by structure-encoded sequences. We have shown that this new data representation preserves query equivalence, and more importantly, through subsequence matching, structured queries can be answered directly without resorting to expensive join operations. Moreover, the XSeq infrastructure unifies indices on both the content and the structure of XML documents, hence it achieves an additional performance advantage over methods indexing either just content or structure, or indexing them separately.
2866284
BLINKS: ranked keyword searches on graphs
Query processing over graph-structured data is enjoying a growing number of applications. A top-k keyword search query on a graph finds the top k answers according to some ranking criteria, where each answer is a substructure of the graph containing all query keywords. Current techniques for supporting such queries on general graphs suffer from several drawbacks, e.g., poor worst-case performance, not taking full advantage of indexes, and high memory requirements. To address these problems, we propose BLINKS, a bi-level indexing and query processing scheme for top-k keyword search on graphs. BLINKS follows a search strategy with provable performance bounds, while additionally exploiting a bi-level index for pruning and accelerating the search. To reduce the index space, BLINKS partitions a data graph into blocks: The bi-level index stores summary information at the block level to initiate and guide search among blocks, and more detailed information for each block to accelerate search within blocks. Our experiments show that BLINKS offers orders-of-magnitude performance improvement over existing approaches.
5266558
Resilient peer-to-peer streaming
We consider the problem of distributing "live" streaming media content to a potentially large and highly dynamic population of hosts. Peer-to-peer content distribution is attractive in this setting because the bandwidth available to serve content scales with demand. A key challenge, however, is making content distribution robust to peer transience. Our approach to providing robustness is to introduce redundance; both in network paths and in data. We use multiple, diverse distribution trees to provide redundancy in network paths and multiple description coding (MDC) to provide redundancy in data. We present a simple tree management algorithm that provides the necessary path diversity and describe an adaptation framework for MDC based on scalable receiver feedback. We evaluate these using MDC applied to real video data coupled with real usage traces from a major news site that experienced a large flash crowd for live streaming content. Our results show very significant benefits in using multiple distribution trees and MDC, with a 22 dB improvement in PSNR in some cases.
15947104
Permissible Observability Relations in FSM Networks
Previous attempts to capture the phenomenon of output don't care sequences for a component in an FSM network have been incomplete. We demonstrate that output don't care sequences for a component can be expressed using a set of observability relations given that its state transition function is kept unchanged. Each observability relation is permissible in the sense that any implementation compatible with one of them is feasible. The representation for a set of permissible observability relations is not unique. We provide a method to find a set with the minimum number of permissible relations. We briefly discuss the exploitation of permissible observability relations in state minimization, circuit implementation and signal encoding. We have implemented these methods and present some preliminary results on a few small artificially constructed examples.