Encapsulation of multiplicity and sparsity in multidimensional query execution systems

• US 9,069,837 B2
• Filed: 12/18/2013
• Issued: 06/30/2015
• Est. Priority Date: 10/18/2011
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Grosset, Robin N., Vazquez, Jose, Zou, Yu
• Primary Examiner(s): Lee, Wilson
• Application Number:
  US14/133,339
• Publication Number:
  US 20140108330A1
• Time in Patent Office: 559 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 16/00 Information retrieval; Database structures therefor; File system structures therefor
• CPC Class Codes: G06F 16/283 Multi-dimensional databases or data warehouses, e.g. MOLAP or ROLAP

Abstract

Provided are techniques for processing a multidimensional query. For each multidimensional expression in the multidimensional query, the multidimensional expression is evaluated to generate a representation that includes an evaluation context, a degeneration status, and condensed value storage that does not store data that would be replicated due to degeneration, and the representation is stored.

Claims

1. A method for processing a multidimensional query, comprising:

providing, using a processor of a computer, an On-Line Analytical Processing (OLAP) database that presents multidimensional data having dimensions;

for each multidimensional expression in the multidimensional query that specifies a subset of dimensions from the dimensions of the multidimensional data,

evaluating, the multidimensional expression to generate a representation by generating;

an evaluation context specifying members of the subset of dimensions, wherein some of the dimensions in the subset are non-degenerated dimensions, and remaining dimensions in the subset are degenerated dimensions, and wherein a degenerated dimension is one in which there is a same result for the evaluation of the multidimensional expression for different members of the degenerated dimension,

a condensed value storage that stores values in a table for members of the non-degenerated dimensions, and

a degeneration status that specifies members of the degenerated dimensions that are not stored in the condensed value storage; and

storing the representation.

2. The method of claim 1, wherein the evaluation context matches a result of the evaluation with a corresponding tuple in the evaluation context.

3. The method of claim 1, wherein the condensed value storage stores non-empty cells of the non-degenerated dimensions without storing repeated values for the degenerated dimensions.

4. The method of claim 1, further comprising:

parsing the multidimensional query to identify each multidimensional expression.

5. The method of claim 1, further comprising:

determining whether the multidimensional expression has a single operand; and

in response to determining that the multidimensional expression has a single operand, performing the evaluation.

6. A computer program product for processing a multidimensional query, the computer program product comprising:

a non-transitory computer readable storage medium having computer readable program code embodied therewith, the computer readable program code,

when executed by a processor of a computer, is configured to perform;

providing an On-Line Analytical Processing (OLAP) database that presents multidimensional data having dimensions;

for each multidimensional expression in the multidimensional query that specifies a subset of dimensions from the dimensions of the multidimensional data,

evaluating the multidimensional expression to generate a representation by generating;

an evaluation context specifying members of the subset of dimensions, wherein some of the dimensions in the subset are non-degenerated dimensions, and remaining dimensions in the subset are degenerated dimensions, and wherein a degenerated dimension is ones in which there is a same result for the evaluation of the multidimensional expression for different members of the degenerated dimension,

a condensed value storage that stores values in a table for members of the non-degenerated dimensions, and

a degeneration status that specifies members of the degenerated dimensions that are not stored in the condensed value storage; and

storing the representation.

7. The computer program product of claim 6, wherein the evaluation context matches a result of the evaluation with a corresponding tuple in the evaluation context.

8. The computer program product of claim 6, wherein the condensed value storage stores non-empty cells of the non-degenerated dimensions without storing repeated values for the degenerated dimensions.

9. The computer program product of claim 6, wherein the computer readable program code, when executed by the processor of the computer, is configured to perform:

parsing the multidimensional query to identify each multidimensional expression.

10. The computer program product of claim 6, wherein the computer readable program code, when executed by the processor of the computer, is configured to perform:

determining whether the multidimensional expression has a single operand; and

in response to determining that the multidimensional expression has a single operand, performing the evaluation.

11. A computer system for processing a multidimensional query, comprising:

a processor; and

a storage device coupled to the processor, wherein the storage device has stored thereon a program, and wherein the processor is configured to execute instructions of the program to perform operations, wherein the operations comprise;

providing an On-Line Analytical Processing (OLAP) database that presents multidimensional data having dimensions;

for each multidimensional expression in the multidimensional query that specifies a subset of dimensions from the dimensions of the multidimensional data,

evaluating the multidimensional expression to generate a representation by generating;

an evaluation context specifying members of the subset of dimensions, wherein some of the dimensions in the subset are non-degenerated dimensions, and remaining dimensions in the subset are degenerated dimensions, and wherein a degenerated dimension is one in which there is a same result for the evaluation of the multidimensional expression for different members of the degenerated dimension,

a condensed value storage that stores values in a table for members of the non-degenerated dimensions, and

a degeneration status that specifies members of the degenerated dimensions that are not stored in the condensed value storage; and

storing the representation.

12. The computer system of claim 11, wherein the evaluation context matches a result of the evaluation with a corresponding tuple in the evaluation context.

13. The computer system of claim 11, wherein the condensed value storage stores non-empty cells of the non-degenerated dimensions without storing repeated values for the degenerated dimensions.

14. The computer system of claim 11, wherein the operations further comprise:

parsing the multidimensional query to identify each multidimensional expression.

15. The computer system of claim 11, wherein the operations further comprise:

determining whether the multidimensional expression has a single operand; and

in response to determining that the multidimensional expression has a single operand, performing the evaluation.