Sirish Ch’s research while affiliated with University of California, Berkeley and other places

Increasingly pervasive networks are leading towards a world where data is constantly in motion. In such a world, conventional techniques for query processing, which were developed under the assumption of a far more static and predictable computational environment, will not be sufficient. Instead, query processors based on adaptive dataflow will be necessary. The Telegraph project has developed a suite of novel technologies for continuously adaptive query processing. The next generation Telegraph system, called TelegraphCQ, is focused on meeting the challenges that arise in handling large streams of continuous queries over high-volume, highly-variable data streams. In this paper, we describe the system architecture and its underlying technology, and report on our ongoing implementation effort, which leverages the PostgreSQL open source code base. We also discuss open issues and our research agenda.

This paper describes an architecture for composing arbitrarily complex services from simpler services over a Wide Area Network. Services register themselves with a Service Discovery Service, and advertise their capabilities in terms of structural and semantic information about their inputs and outputs. A type system for this information is used to determine the validity of composing two operators. A request for a complex service between source(s) and sink(s) of data is specied as a combination of the output type(s) of the source(s) and the input type(s) of the sink(s) and a (possibly empty) list of intermediate services specied by unique names. We introduce the concept of a path": an ordered sequence of services that, when composed, result in the desired complex service. The concept of a path is further rened to distinguish control paths" from data paths" and logical paths" from physical paths". We have implemented a prototype for the path architecture within the Ninja system. ...

As query engines are scaled and federated, they must cope with highly unpredictable and changeable environments. In the Telegraph project, we are attempting to architect and implement a continuously adaptive query engine suitable for global-area systems, massive parallelism, and sensor networks. To set the stage for our research, we present a survey of prior work on adaptive query processing, focusing on three characterizations of adaptivity: the frequency of adaptivity, the effects of adaptivity, and the extent of adaptivity. Given this survey, we sketch directions for research in the Telegraph project. 1 Introduction Adaptivity has been an inherent -- though largely latent -- aspect of database research for the last three decades. Codd's vision of data independence was predicated on the development of systems that could adapt gracefully and opaquely to changing data and data structures. Query optimization, with its attendant technologies for cost estimation, served as an early dif...