Zenith seminar, friday 27 january 10h30-12h, room 2/124 bat 5 Campus Saint Priest
Database System Support of Simulation Data
LNCC, Rio de Janeiro, Brazil
Supported by increasingly efficient HPC infra-structure, numerical simulations are rapidly expanding to fields such as oil and gas, medicine and meteorology. As simulations become more precise and cover longer periods of time, they may produce files with terabytes of data that need to be efficiently analyzed. In this work, we investigate techniques for managing such data using an array DBMS. We take advantage of multidimensional arrays that nicely models the dimensions and variables used in numerical simulations. However, a naive approach to map simulation data files may lead to sparse arrays, impacting query response time, in particular, when the simulation uses irregular meshes to model its physical domain. We propose efficient techniques to map coordinate values in numerical simulations to evenly distributed cells in array chunks with the use of equi-depth histograms and spacefilling curves. We implemented our techniques in SciDB and, through experiments over real-world data, compared them with two other approaches: row-store and column-store DBMS. The results indicate that multidimensional arrays and column-stores are much faster than a traditional row-store system for queries over a larger amount of simulation data. They also help identifying the scenarios where array DBMSs are most efficient, and those where they are outperformed by column-stores.