Database index techniques

In computer science, a B-tree is a self-balancing tree data structure that maintains sorted data and allows searches, sequential access, insertions, and deletions in logarithmic time. The B-tree generalizes the binary search tree, allowing nodes to have more than two children.

data structure for database query optimization at the expense of write and storage to maintain the index structure

thumb|Left: Recursive subdivision of a cube into octant (solid geometry)|octants. Right: The corresponding octree.

specialized database index to accelerate full-text search

multidimensional search tree for points in k dimensional space

thumb|300px|A point-region quadtree with point data. Bucket capacity 1. thumb|300x300px|Quadtree compression of an image step by step. Left shows the compressed image with the tree bounding boxes while the right shows just the compressed image A quadtree is a tree data structure in which each internal node has exactly four children. Quadtrees are the two-dimensional analog of octrees and are most often used to partition a two-dimensional space by recursively subdividing it into four quadrants or regions. The data associated with a leaf cell varies by application, but the leaf cell represents a

function which maps multidimensional data to one dimension while preserving locality of the data points

In data processing R*-trees are a variant of R-trees used for indexing spatial information. R*-trees have slightly higher construction cost than standard R-trees, as the data may need to be reinserted; but the resulting tree will usually have a better query performance. Like the standard R-tree, it can store both point and spatial data. It was proposed by Norbert Beckmann, Hans-Peter Kriegel, Ralf Schneider, and Bernhard Seeger in 1990.

The UB-tree, also known as the Universal B-Tree, as proposed by Rudolf Bayer and Volker Markl is a balanced tree for storing and efficiently retrieving multidimensional data. Like a B+ tree, information is stored only in the leaves. Records are stored according to Z-order, also called Morton order. Z-order is calculated by bitwise interlacing of the keys.