| 摘要 |
<p>The invention provides a method for searching objects in a database by means of an index data structure (200) which associates object attribute values to collections (205, 206) of spatial elements - such as tiles of a quadtree or cuboids of an octtree - defined to partition a space, herein a predefined number of spatial elements being combinable to a next-level spatial element, the method comprising: searching the index data structure (200) for a first input search pattern and, if the first input search pattern is associated to a first collection (205, 206) of spatial elements through the index data structure (200), including all spatial elements from the first collection (205, 206) into a first candidate set (102a, 102b) of spatial elements, wherein, if the number of spatial elements in the first candidate set (102a, 102b) exceeds a predetermined maximum, some or all of the spatial elements are combined to a reduced number of next-level spatial elements; searching the index data structure (200) for a second input search pattern and, if the second input search pattern is associated to a second collection (205, 206) of spatial elements through the index data structure (200), including all spatial elements from the second collection (205, 206) into a second candidate set (102a, 102b) of spatial elements, wherein, if the number of spatial elements in the second candidate set (102a, 102b) exceeds a predetermined maximum, some or all of the spatial elements are combined to a reduced number of next-level spatial elements; forming, from of the first candidate set and the second candidate set (102a, 102b), a combined candidate set (104a) of spatial elements; and searching, in the combined candidate set (104a) of spatial elements, for objects that match the first input search pattern and the input second search pattern to obtain a set of result objects. Hence, a method is provided that allows a free text search for objects within map data of a mobile navigation device.</p> |
