PostGIS
From HostGISLinux
PostGIS is an extension to the PostgreSQL database server, allowing PostgreSQL to handle "geometry" as a data type. Thus, a PostgreSQL table can hold spatial data, replacing shapefiles or other data sources. This provides all of the flexibility of a database (querying, indexing, sorting, updating and deleting).
Under most circumstances, a properly indexed and tuned PostGreSQL-PostGIS server can perform at least as quickly as a shapefile or other static data source.
PostGIS consists of three components: a shared library which provides access to the underlying geometry functions, stored procedures which must be loaded into each database, and a pair of tables (spatial_ref_sys and geometry_columns) which store metadata about geometry type columns.
