Fast range query estimation by N-level tree histograms

Fast range query estimation by N-level tree histograms

Histograms are a lossy compression technique widely applied in various application contexts, like query optimization, statistical and temporal databases, OLAP applications, data streams, and so on. In most cases, accuracy in reconstructing from the histogram some original information, plays a crucial role. Thus, several proposals for constructing histograms trying to maximize their accuracy, ha...

Size Estimation for Query Results Using Histograms

Query-Condition-Aware Histograms in Selectivity Estimation Method

The paper shows an adaptive approach to the query selectivity estimation problem for queries with a range selection condition based on continuous attributes. The selectivity factor estimates a size of data satisfying a query condition. This estimation is calculated at the initial stage of the query processing for choosing the optimal query execution plan. A non-parametric estimator of probabili...

Approximating sliding windows by cyclic tree-like histograms for efficient range queries

The issue of providing fast approximate answers to range queries on sliding windows with a small consumption of storage space is one of the main challenges in the context of data streams. On the one hand, the importance of this class of queries is widely accepted. They are indeed useful to compute aggregate information over the data stream, allowing us to extract from it more abstract knowledge...

Estimation of Tree Biomass at Individual tree, Sample plot and Hybrid Level using Drone Images

Two-dimensional image conversion algorithms to 3D data create the hope that the structural properties of trees can be extracted through these images. In this study, the accuracy of biomass estimation in tree, plot, and hybrid levels using UAVs images was investigated. In 34.8 ha of Sisangan Forest Park, using a quadcopter, 854 images from an altitude of 100 meters above ground were acquired. SF...