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# Lecture 22 - SS-trees,SR-trees,P-trees Notes | EduRev

## : Lecture 22 - SS-trees,SR-trees,P-trees Notes | EduRev

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Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

The Lecture Contains:
SS-tree
Bounding spheres and bounding rectangles
SR-tree
Structure and algorithms
Performance
P-tree
Search performance and overlap
Effect of dimensionality on overlap

Page 2

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

The Lecture Contains:
SS-tree
Bounding spheres and bounding rectangles
SR-tree
Structure and algorithms
Performance
P-tree
Search performance and overlap
Effect of dimensionality on overlap

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

SS-tree
Uses bounding spheres instead of bounding rectangles

Page 3

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

The Lecture Contains:
SS-tree
Bounding spheres and bounding rectangles
SR-tree
Structure and algorithms
Performance
P-tree
Search performance and overlap
Effect of dimensionality on overlap

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

SS-tree
Uses bounding spheres instead of bounding rectangles

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

SS-tree
Uses bounding spheres instead of bounding rectangles
Motivated by range and kNN queries which are hyper-spheres
Center of sphere is centroid of points
Maintains total number of points in the subtree
Higher fanout due to smaller storage requirements
Considerable volume overlap
Split axis is chosen based on variance
Better than R*-trees

Page 4

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

The Lecture Contains:
SS-tree
Bounding spheres and bounding rectangles
SR-tree
Structure and algorithms
Performance
P-tree
Search performance and overlap
Effect of dimensionality on overlap

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

SS-tree
Uses bounding spheres instead of bounding rectangles

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

SS-tree
Uses bounding spheres instead of bounding rectangles
Motivated by range and kNN queries which are hyper-spheres
Center of sphere is centroid of points
Maintains total number of points in the subtree
Higher fanout due to smaller storage requirements
Considerable volume overlap
Split axis is chosen based on variance
Better than R*-trees

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

Bounding spheres and bounding rectangles
SS-tree has regions with shorter diameters
R*-tree has regions with smaller volumes
How?

Page 5

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

The Lecture Contains:
SS-tree
Bounding spheres and bounding rectangles
SR-tree
Structure and algorithms
Performance
P-tree
Search performance and overlap
Effect of dimensionality on overlap

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

SS-tree
Uses bounding spheres instead of bounding rectangles

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

SS-tree
Uses bounding spheres instead of bounding rectangles
Motivated by range and kNN queries which are hyper-spheres
Center of sphere is centroid of points
Maintains total number of points in the subtree
Higher fanout due to smaller storage requirements
Considerable volume overlap
Split axis is chosen based on variance
Better than R*-trees

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

Bounding spheres and bounding rectangles
SS-tree has regions with shorter diameters
R*-tree has regions with smaller volumes
How?

Objectives_template
Module 5: Disk-based Index Structures
Lecture 22: SS-trees,SR-trees,P-trees

Bounding spheres and bounding rectangles
SS-tree has regions with shorter diameters
R*-tree has regions with smaller volumes
How?
Rectangles in -dimensions

Diameter: Between 0 and

Volume: Between 0 and 1
Spheres in -dimensions

Diameter: Between 0 and

Volume: Between 0 and

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