空间索引详解
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In general: • Spatial data objects often cover areas in multidimensional spaces. • Spatial data objects are not well-represented by point-location. • An ‘index’ based on an object’s spatial location is desirable.
6
The Indexing Approach
• A B-Tree (Rosenberg & Snyder, 1981) is an ordered, dynamic, multi-way structure of order m (i.e. each node has at most m children).
4
Spatial Database (Ic)
• Consider: Given a city map, ‘index’ all university buildings in an efficient structure for quick relational-topological search.
they represent. • Leaves in the structure all appear on the same level. • Spatial searching requires visiting only a small number of nodes. • The index is completely dynamic: inserts and deletes can be intermixed
Overview
• Representing and handling spatial data • The R-Tree indexing approach, style and structure • Properties and notions • Searching and inserting index Entry-records • Deleting and updating • Performance analyses • Node splitting algorithms • Derivatives of the R-Trees • Applications
• Consider: Given a city map, ‘index’ all university buildings in an efficient structure for quick topological search.
Spatial object: Contour (outline) of the area around the building(s). Minimum bounding region (MBR) of the object.
• The B-Tree is designed (among other objectives): – to branch out this large number of directions, and – to contain a lot of keys in each node so that the height of the tree is relatively short.
• Involves 2D regions. • Need to support 2D range queries. • Multiple return values desired: Answering a query region by reporting all
spatial objects that are fully-contained-in or overlapping the query region (Spatial-Access Method – SAM).
• The keys and the subtrees are arranged in the fashion of a search tree.
M
EH
P TX
BD FG I KL
N O Q S VW Y Z
• Each node may contain a large number of keys, and the number of subtrees in each node, then, may also be large.
2
Spatial Database (Ia)
• Consider: Given a city map, ‘index’ all university buildings in an efficient structure for quick topological search.
3
Spatial Database (Ib)
R-Tree: Spatial Representation on a Dynamic-Index Structure
Advanced Algorithms & Data Structures Lecture Theme 03 – Part I
K. A. Mohamed Summer Semester 2006
7
The R-Tree Index Structure
• An R-Tree is a height-balanced tree, similar to a B-Tree. • Index records in the leaf nodes contain pointers to the actual spatial-objects
MBR of the city neighbourhoods. MBR of the city defining the overall search region.
5源自文库
Spatial Database (II)
Notion: To retrieve data items quickly and efficiently according to their spatial locations.
6
The Indexing Approach
• A B-Tree (Rosenberg & Snyder, 1981) is an ordered, dynamic, multi-way structure of order m (i.e. each node has at most m children).
4
Spatial Database (Ic)
• Consider: Given a city map, ‘index’ all university buildings in an efficient structure for quick relational-topological search.
they represent. • Leaves in the structure all appear on the same level. • Spatial searching requires visiting only a small number of nodes. • The index is completely dynamic: inserts and deletes can be intermixed
Overview
• Representing and handling spatial data • The R-Tree indexing approach, style and structure • Properties and notions • Searching and inserting index Entry-records • Deleting and updating • Performance analyses • Node splitting algorithms • Derivatives of the R-Trees • Applications
• Consider: Given a city map, ‘index’ all university buildings in an efficient structure for quick topological search.
Spatial object: Contour (outline) of the area around the building(s). Minimum bounding region (MBR) of the object.
• The B-Tree is designed (among other objectives): – to branch out this large number of directions, and – to contain a lot of keys in each node so that the height of the tree is relatively short.
• Involves 2D regions. • Need to support 2D range queries. • Multiple return values desired: Answering a query region by reporting all
spatial objects that are fully-contained-in or overlapping the query region (Spatial-Access Method – SAM).
• The keys and the subtrees are arranged in the fashion of a search tree.
M
EH
P TX
BD FG I KL
N O Q S VW Y Z
• Each node may contain a large number of keys, and the number of subtrees in each node, then, may also be large.
2
Spatial Database (Ia)
• Consider: Given a city map, ‘index’ all university buildings in an efficient structure for quick topological search.
3
Spatial Database (Ib)
R-Tree: Spatial Representation on a Dynamic-Index Structure
Advanced Algorithms & Data Structures Lecture Theme 03 – Part I
K. A. Mohamed Summer Semester 2006
7
The R-Tree Index Structure
• An R-Tree is a height-balanced tree, similar to a B-Tree. • Index records in the leaf nodes contain pointers to the actual spatial-objects
MBR of the city neighbourhoods. MBR of the city defining the overall search region.
5源自文库
Spatial Database (II)
Notion: To retrieve data items quickly and efficiently according to their spatial locations.