| 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 (51) - such as tiles of a quadtree or cuboids of an octtree - defined to partition a space, herein a predefined number of spatial elements (51) being combinable to a next-level spatial element (52), 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 (51) through the index data structure (200), including all spatial elements (51) from the first collection (205, 206) into a first candidate set (102a, 102b) of spatial elements (51), wherein, if the number of spatial elements (51) in the first candidate set (102a, 102b) exceeds a predetermined maximum, some or all of the spatial elements (51) are combined to a reduced number of next-level spatial elements (52); 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 (51) through the index data structure (200), including all spatial elements (51) from the second collection (205, 206) into a second candidate set (102a, 102b) of spatial elements (51), wherein, if the number of spatial elements (51) in the second candidate set (102a, 102b) exceeds a predetermined maximum, some or all of the spatial elements (51 ) are combined to a reduced number of next-level spatial elements (52); forming, from of the first candidate set and the second candidate set (102a, 102b), a combined candidate set (104a) of spatial elements (51, 52); and searching, in the combined candidate set (104a) of spatial elements (51, 52), 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> |
