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Databases as a service (DBaaS) transfer the advantages of cloud computing to data management systems, which is important for the big data era. The allocation in a DBaaS system, i.e., the mapping from databases to nodes of the infrastructure, influences performance, utilization, and cost-effectiveness of the system. Modeling databases and the underlying infrastructure as weighted graphs and using graph...
Fault tolerance is an important challenge for supporting critical big data analytic operations. Most existing solutions only provide fault tolerant data replication, requiring failed queries to be restarted. This approach is insufficient for long-running time-sensitive analytic queries, due to lost query progress. Several solutions provide intra-query fault tolerance. However, these focus on distributed...
Consistent query answering is a principled approach to query answering on inconsistent databases: when an inconsistent database has more than one plausible repair, queries are answered by returning the intersection of the query answers over all repairs. In this paper, we study consistent query answering over temporal databases relative to atemporal integrity constraints. A temporal database is conceptually...
Information is playing an important role in our lives. One of the major sources of information is databases. Databases and database technology are having major impact on the growing use of computers. In order to retrieve information from a database, one needs to formulate a query in such way that the computer will understand and produce the desired output. Generally, query processing is handled by...
Graph pattern matching is a hot spot in the big data era, which is to find answer graphs matching a given query graph in a data graph of graph databases. "Matching" means two graphs satisfy some relation, such as isomorphism, simulation, bisimulation, etc. Since there are seldom algorithms for the subgraph bisimulation, our work commits to solve the graph pattern matching problem involving...
Queries with aggregation represent an important aspect in database systems. They are widely used in online analytical processing, decision support systems, and data analytics. Aggregate functions usually perform calculations on a set of values of a particular column and return a single summarized value. However, handling aggregate functions becomes a challenge when dealing with uncertain data as there...
A social media message that is forwarded (e.g., Retweeted in Twitter) by many users may diffuse widely. Such a 'viral' message may have a major impact in the real world. If the content maligns a company, the company must respond as quickly as possible to defend its brand image. Timely knowledge about what kinds of information are diffusing in social media is thus quite important. We have developed...
With high and growing supply of Database-as-a-Service solutions from cloud platform vendors, many enterprises still show moderate to low demand for them. Even though migration to a DaaS solution might result in a significantly reduced bill for IT maintenance, data security and privacy issues are among the reasons of low popularity of these services. Such a migration is also often only justified if...
The Florida Department of Health funds beach water sampling for 34 of Florida's coastal counties. Mote Marine Laboratory, in conjunction with the Gulf of Mexico Coastal Ocean Observing System (GCOOS) developed an automated data harvester that used Web scraping technology to capture the reported data from each monitored county and store the data in a MySQL database. The database was queried nightly...
Search engines have always played an important role in helping web users to rapidly find information on the Web. However, their function is limited to returning a list of query relevant documents with reasonably good precision, but huge recall. The task of actually processing the returned documents to get the required information is the responsibility of the user. In recent years, Question-Answer...
Recent testing techniques for database applications typically include generation of both program inputs and database states (synthetic data). The quality of such test cases is evaluated on the basis of structural coverage of the host language (e.g., Java), whereas, the quality of test cases for the embedded language (e.g., SQL) is evaluated separately using mutation testing. In mutation testing, several...
The setting in which similarity querying of metric data is outsourced to a service provider. Users query the server for the most similar data objects and data is revealed only to trusted users and not to anyone else. The need for privacy may be due to the data being sensitive (eg. in medicine), valuable (eg. in astronomy) or otherwise confidential. In this work, image retrieval on metric data of outsourced...
To manipulate a large video database, effective video indexing and retrieval are required. A large number of video retrieval algorithms have been presented for frame wise user query or video content query, whereas few video-sequence matching algorithms have been investigated. In this paper, we propose an efficient algorithm for video sequence matching using the modified Hausdorff distance and the...
In this paper, we focus on providing users with an effective and efficient way to extract useful information from complex structured XML databases. We propose a new query mechanism to provide users with the ability to refine the ambiguous semantics of the initiative ATP query before execution, thus we can avoid identifying meaningful answers from large amount of irrelevant results returned by existing...
This paper describes architecture for mobile databases where data is distributed over mobile devices. We propose strategies for query execution during mobility. The underlying architecture is based on 3G telephone networks.
Skyline queries are well-known for their intuitive query formalization and easy to understand semantics for selecting the most interesting data objects from large data sets. They naturally fill the gap between set-based queries using strict predicates and only few personalization options and rank-aware database retrieval, offering a high degree of personalization at the cost of very complex query...
In this demonstration we present MYOLAP, a Java-based tool that allows OLAP analyses to be personalized and enhanced by expressing “soft” query constraints in the form of user preferences. MYOLAP is based on a novel preference algebra and a preference evaluation algorithm specifically devised for the OLAP domain. Preferences are formulated either visually or through an extension of the MDX language,...
The study of skylines and their variants has received considerable attention in recent years. Skylines are essentially sets of most interesting (undominated) tuples in a database. However, since the skyline is often very large, much research effort has been devoted to identifying a smaller subset of (say k) “representative skyline” points. Several different definitions of representative skylines have...
Complex SQL queries are widely used today, but it is rather difficult to check if a complex query has been written correctly. Formal verification based on comparing a specification with an implementation is not applicable, since SQL queries are essentially a specification without any implementation. Queries are usually checked by running them on sample datasets and checking that the correct result...
Real-world databases often have extremely complex schemas. With thousands of entity types and relationships, each with a hundred or so attributes, it is extremely difficult for new users to explore the data and formulate queries. Schema free query interfaces (SFQIs) address this problem by allowing users with no knowledge of the schema to submit queries. We postulate that SFQIs should deliver the...
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