To share or not to share?

Ryan Johnson, Nikos Hardavellas, Ippokratis Pandis, Naju G. Mancheril, Stavros Harizopoulos, Kivanc Sabirli, Anastasia Ailamaki, Babak Falsafi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

21 Scopus citations


Intuitively, aggressive work sharing among concurrent queries in a database system should always improve performance by eliminating redundant computation or data accesses. We show that, contrary to common intuition, this is not always the case in practice, especially in the highly parallel world of chip multiprocessors. As the number of cores in the system increases, a trade-off appears between exploiting work sharing opportunities and the available parallelism. To resolve the trade-off, we develop an analytical approach that predicts the effect of work sharing in multi-core systems. Database systems can use the model to determine, statically or at runtime, whether work sharing is beneficial and apply it only when appropriate. The contributions of this paper are as follows. First, we introduce and analyze the effects of the trade-off between work sharing and parallelism on database systems running complex decision-support queries. Second, we propose an intuitive and simple model that can evaluate the trade-off using real-world measurement approximations of the query execution processes. Furthermore, we integrate the model into a prototype database execution engine, and demonstrate that selective work sharing according to the model outperforms never-share static schemes by 20% on average and always-share ones by 2.5x.

Original languageEnglish (US)
Title of host publication33rd International Conference on Very Large Data Bases, VLDB 2007 - Conference Proceedings
EditorsJohannes Gehrke, Christoph Koch, Minos Garofalakis, Karl Aberer, Carl-Christian Kanne, Erich J. Neuhold, Venkatesh Ganti, Wolfgang Klas, Chee-Yong Chan, Divesh Srivastava, Dana Florescu, Anand Deshpande
PublisherAssociation for Computing Machinery, Inc
Number of pages12
ISBN (Electronic)9781595936493
StatePublished - Jan 1 2007
Event33rd International Conference on Very Large Data Bases, VLDB 2007 - Vienna, Austria
Duration: Sep 23 2007Sep 27 2007

Publication series

Name33rd International Conference on Very Large Data Bases, VLDB 2007 - Conference Proceedings


Other33rd International Conference on Very Large Data Bases, VLDB 2007

ASJC Scopus subject areas

  • Hardware and Architecture
  • Information Systems and Management
  • Information Systems
  • Software


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