Cost models for overlapping and multi-version B-trees

Overlapping and multi-version techniques are two popular frameworks that transform an ephemeral index into a multiple logical-tree structure in order to support versioning databases. Although both frameworks have produced numerous efficient indexing methods, their performance analysis is rather limited; as a result, there is no clear understanding about the behavior of the alternative structures and the choice of the best one, given the data and query characteristics. Furthermore, query optimization based on these methods is currently impossible. These are serious problems due to the incorporation of overlapping and multi-version techniques in several traditional (e.g. banking) and emerging (e.g. spatio-temporal) applications. In this paper, we propose frameworks for reducing the performance analysis of overlapping and multi-version structures to that of the corresponding ephemeral structures, thus simplifying the problem significantly. The frameworks lead to accurate cost models that predict the sizes of the trees, the node accesses and query selectivity. Although we focus on B-tree-based structures, the proposed models can be employed with a variety of indexes.