To Share or Not To Share?

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 ...

• Type: Conference
• Year: 2007
• Where: VLDB
• Authors: Ryan Johnson, Nikos Hardavellas, Ippokratis Pandis, Naju Mancheril, Stavros Harizopoulos, Kivanc Sabirli, Anastassia Ailamaki, Babak Falsafi
• Keywords: Database, Trade-off, VLDB 2007, Work Sharing, Work Sharing Opportunities