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Array database systems are architected for scientific and engineering applications. In these applications, the value of a cell is often imprecise and uncertain. There are at least two reasons that a Monte Carlo query processing algorithm is usually required for such uncertain data. Firstly, a probabilistic graphical model must often be used to model correlation, which requires a Monte Carlo inference...
Modern database systems increasingly make use of networked storage. This storage can be in the form of SAN's or in the form of shared-nothing nodes in a cluster. One type of attack on databases is arbitrary modification of data in a database through the file system, bypassing database access control. Additionally, for many applications, ensuring strict and definite authenticity of query source and...
We present a replication-based approach that realizes both fast and highly-available stream processing over wide area networks. In our approach, multiple operator replicas send outputs to each downstream replica so that it can use whichever data arrives first. To further expedite the data flow, replicas run independently, possibly processing data in different orders. Despite this complication, our...
Scientific and intelligence applications have special data handling needs. In these settings, data does not fit the standard model of short coded records that had dominated the data management area for three decades. Array database systems have a specialized architecture to address this problem. Since the data is typically an approximation of reality, it is important to be able to handle imprecision...
We present a replication-based approach that enables both fast and reliable stream processing over wide area networks. Our approach replicates stream processing operators in a manner where operator replicas compete with each other to make the earliest impact. Therefore, any processing downstream from such replicas can proceed by relying on the fastest replica without being held back by slow or failed...
We present a collaborative, self-configuring high availability (HA) approach for stream processing that enables low-latency failure recovery while incurring small run-time overhead. Our approach relies on a novel fine-grained checkpointing model that allows query fragments at each server to be backed up at multiple other servers and recovered collectively (in parallel) when there is a failure. In...
Networked information systems require strong security guarantees because of the new threats that they face. Various forms of encryption have been proposed to deal with this problem. In a database system, there are often two contradictory goals: security of the encryption and fast performance of queries. There have been a number of proposals of database encryption schemes to facilitate queries on encrypted...
Overload management has been an important problem for large-scale dynamic systems. In this paper, we study this problem in the context of our Borealis distributed stream processing system. We show that server nodes must coordinate in their load shedding decisions to achieve global control on output quality. We describe a distributed load shedding approach which provides this coordination by upstream...
Mobile computers and wireless networks are emerging technologies which will soon make ubiquitous computing a reality. In the wireless environment, mobile clients may often be disconnected from stationary server machines or may have only a low-bandwidth channel for sending messages to servers. This environment raises new challenges for the support of database applications for three reasons: 1) the...
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