TRAC: toward recency and consistency reporting in a database with distributed data sources

  • Authors:
  • Jiansheng Huang;Jeffrey F. Naughton;Miron Livny

  • Affiliations:
  • University of Wisconsin at Madison, Madison, WI;University of Wisconsin at Madison, Madison, WI;University of Wisconsin at Madison, Madison, WI

  • Venue:
  • VLDB '06 Proceedings of the 32nd international conference on Very large data bases
  • Year:
  • 2006

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Abstract

Distributed computing environments, including workflows in computational grids, present challenges for monitoring, as the state of the system may be captured only in logs distributed throughout the system. One approach to monitoring such systems is to "sniff" these distributed logs and to store their transformed content in a DBMS. This centralizes the state and exposes it for querying; unfortunately, it also creates uncertainty with respect to the recency and consistency of the data. Previous related work has focused on allowing queries to express currency and consistency constraints, which are then enforced by "pulling" data from the distributed sources on demand, or by requiring synchronous updates of a centralized data store. In some instances this is impossible due to legacy system issues or inefficient as the system scales to large numbers of processors. Accordingly, we propose that instead of enforcing consistency and recency, such monitoring systems should report these properties along with query results, with the hope that this will allow the data to be appropriately interpreted. We present techniques for reporting consistency and recency for queries and evaluate them with respect to efficiency and precision. Finally, we describe our prototype implementation and present experimental results of our techniques.