Using SQLite

R*Trees and Spatial Indexing Module

The R*Tree module is a standard extension to SQLite that provides an index structure that is optimized for multi-dimensional ranged data. The R*Tree name refers to the internal algorithm used to organize and query the stored data. For example, in a two-dimensional R*Tree, the rows might contain rectangles, in the form of a minimum and maximum longitude value, along with a minimum and maximum latitude. Queries can be made to quickly find all of the rows that contain or overlap a specific geological location or area. Adding more dimensions, such as altitude, allows more complex and specific searches.

R*Trees are not limited to just spacial information, but can be used with any type of numeric range data that includes pairs of minimum and maximum values. For example, an R*Tree table might be used to index the start and stop times of events. The index could then quickly return all of the events that were active at a specific point or range of time.

The R*Tree implementation included with SQLite can index up to five dimensions of data (five sets of min/max pairs). Tables consist of an integer primary key column, followed by one to five pairs of floating-point columns. This will result in a table with an odd number of 3 to 11 columns. Data values must always be given in pairs. If you wish to store a point, simply use the same value for both the minimum and maximum component.

Generally, R*Trees act as detail tables for more traditional tables. A traditional ...