Efficient Query Processing for Spatial and Temporal Data Exploration

Core to many scientific and analytics applications are spatial data capturing the position or shape of objects in space, and time series recording the values of a process over time. Effective analysis of such data requires a shift from confirmatory pipelines to exploratory ones. However, there is a mismatch between the requirements of spatial and temporal data exploration and the capabilities of the data management solutions available today. First, traditional spatial query operators evaluate spatial relations with time-consuming geometric tests that oppose the interactivity expected from exploratory applications, creating an undue overhead. Second, spatial access methods are built on top of rough geometric object approximations that do not capture the complex structure and distribution of today's spatial data and are thus inefficient. Third, traditional indexes are typically built upfront before queries can be processed and over single data attributes, thus precluding interactive accesses to interesting data subsets that may be specified with constraints on multiple attributes. Finally, existing access methods scale poorly with increasingly granular spatial and temporal data originating from ever more precise data acquisition technologies and ever faster computing infrastructure.

This thesis introduces a novel family of spatial and temporal access methods and query operators that aim to bridge the gap between existing data management techniques and data exploration applications. We show that spatial query operators can be decomposed into primitive graphics operations that are efficiently executed by graphics hardware (GPU) and allow to trade accuracy for interactivity. Furthermore, we design access methods that adapt to data characteristics, data growth trends, and workload access patterns, thereby providing scalable performance for ad-hoc queries over increasing data amounts. Specifically, we introduce a spatial approximation that adapts to the structural properties and distribution of the data, and propose spatial and time series access methods that leverage similarities between data items and support filtering over multiple attributes. Finally, we present an approach that indexes data incrementally, using queries as hints for optimizing data access.