Compression scheme for improving cache behavior in database systems

1. A method, comprising:

identifying, from an index structure stored in memory, a reference minimum bounding shape that encloses at least one minimum bounding shape, each of the at least one minimum bounding shape corresponding to a data object associated with a leaf node of the index structure; and

associating, using one or more processors, coordinates of a point of the at least one minimum bounding shape with a set of first values to produce a relative representation of the at least one minimum bounding shape, the set of first values being calculated relative to coordinates of a reference point of the reference minimum bounding shape such that each first value comprises a first number of significant bits fewer than a second number of significant bits representing a second value associated with a corresponding one of absolute coordinates of the point.

2. The method of claim 1 , further comprising:

compressing the relative representation using a finite level of quantization to produce a quantized representation of the at least one minimum bounding shape.

3. The method of claim 2 , wherein the compressing comprises:

choosing the finite level of quantization from a set of quantization levels.

4. The method of claim 2 , further comprising:

storing the quantized representation in at least one node of the index structure.

5. The method of claim 2 , further comprising:

responsive to a query, searching the index structure using the quantized representation.

6. The method of claim 5 , wherein the searching comprises:

transforming a minimum bounding shape corresponding to the query into another quantized representation.

7. The method of claim 6 , wherein the searching comprises:

comparing the quantized representation with the other quantized representation to determine whether there is an overlap.

8. The method of claim 7 , wherein the searching comprises:

determining that an entry corresponding to the quantized representation matches the query responsive to the overlap being identified.

9. The method of claim 2 , further comprising:

recalculating the quantized representation responsive to a change in the at least one minimum bounding shape being identified.

10. The method of claim 1 , where the data object is stored in main memory or a disk.

11. The method of claim 1 , wherein the index structure comprises at least one of an R-tree, an R* -tree, an R+-tree or a Hilbert R-tree.

12. A system, comprising:

memory to store an index structure; and

one or more processors to execute a compression engine, the compression engine configured to:

identify, from the index structure, a reference minimum bounding shape that encloses at least one minimum bounding shape, each of the at least one minimum bounding shape corresponding to a data object associated with a leaf node of the index structure; and

associate coordinates of a point of the at least one minimum bounding shape with a set of first values to produce a relative representation of the at least one minimum bounding shape, the set of first values being calculated relative to coordinates of a reference point of the reference minimum bounding shape such that each first value comprises a first number of significant bits fewer than a second number of significant bits representing a second value associated with a corresponding one of absolute coordinates of the point.

13. The system of claim 12 , wherein the compression engine is configured to compress the relative representation using a finite level of quantization to produce a quantized representation of the at least one minimum bounding shape.

14. The system of claim 13 , wherein at least one internal node of the index structure comprises a plurality of entries including a first entry, a second entry and a third entry, the first entry storing the reference minimum bounding shape, the second entry storing a pointer to a child node, and the third entry storing the quantized representation.

15. The system of claim 14 , wherein the pointer is the only pointer stored in the at least one internal node.

16. The system of claim 13 , wherein at least one non-root node of the index structure comprises a plurality of entries including a first entry and a second entry, the first entry storing a pointer to a child node, and the second entry storing the quantized representation.

17. The system of claim 16 , wherein the reference minimum bounding share is stored only in a root node of the index structure.

18. The system of claim 13 , wherein the reference minimum bounding shape or the quantized representation is stored only in non-leaf nodes of the index structure.

19. A non-transitory computer-readable storage device storing instructions that, when executed by one or more processors, cause the one or more processor to perform operations comprising:

identifying, from an index structure stored in memory, a reference minimum bounding shape that encloses at least one minimum bounding shape, each of the at least one minimum bounding shape corresponding to a data object associated with a leaf node of the index structure; and

associating coordinates of a point of the at least one minimum bounding shape with a set of first values to produce a relative representation of the at least one minimum bounding shape, the set of first values being calculated relative to coordinates of a reference point of the reference minimum bounding shape such that each first value comprises a first number of significant bits fewer than a second number of significant bits representing a second value associated with a corresponding one of absolute coordinates of the point.

20. The non-transitory computer-readable storage device of claim 19 , wherein the operation comprises:

compressing the relative representation using a finite level of quantization to produce a quantized representation of the at least one minimum bounding shape.