Executing conditions with negation operators in analytical databases

Patent metadata

Field	Value
Publication number	US-10210223-B2
Application number	US-201514923690-A
Country	US
Kind code	B2
Filing date	Oct 27, 2015
Priority date	Oct 27, 2015
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

Embodiments of the present invention provide a method and system for processing a query on a set of data blocks in analytical databases. The query is on a set of data blocks, having at least one attribute and specifies at least one selection condition on the attribute. The selection condition is associated with at least one selection expression. Attribute value information on each attribute is generated for each data block. Next, a condition is generated on each attribute to negate the selection expression, if the selection expression has a negation operator. Additional conditions are generated for each selection expression that does not contain a negation operation. The attribute value is used to select the positive and negative subsets of data blocks for each condition. Next, a negative subset that does not require processing to evaluate the query is skipped and the positive subsets and the non-skipped negative subsets are processed.

First claim

What is claimed is:

1. A computer program product comprising:
a computer readable storage medium and program instructions stored on the computer readable storage medium, the program instructions comprising:
program instructions to receive a set of data blocks and a query, wherein the set of data blocks comprises at least one attribute and, wherein the query specifies a selection condition on the at least one attribute, wherein the selection condition comprises at least one selection expression;
program instructions to generate an attribute value information on the at least one attribute, for each data block of the set of data blocks;
program instructions to generate a first condition on the at least one attribute, wherein the first condition negates each selection expression of the at least one selection expression, when the selection expression comprises a negation operator;
program instructions to generate a first set of conditions that comprises the generated first condition on the at least one attribute, and each of the at least one selection expression that does not comprise a negation operator;
program instructions to select a positive subset of data blocks, of the set of data blocks, for each condition of the first set of conditions, wherein the positive subset of data blocks, of the set of data blocks satisfies a condition of the first set of conditions, using the attribute value information;
program instructions to select a negative subset of data blocks, of the set of data blocks, for each condition of the first set of conditions, wherein the negative subset of data blocks, of the set of data blocks does not satisfies a condition of the first set of conditions, using the attribute value information;
program instructions to determine a skipped portion of the negative subsets of the data blocks, using the selection condition, and a non-skipped portion of the negative subsets of the data blocks, using the selection condition;
program instructions to generate result data, wherein the generated result data comprises:
program instructions to process the positive subset of the data blocks; and
program instructions to process the negative portion non-skipped portion of the negative subsets of the data blocks.

2. The computer program product of claim 1 , wherein the program instructions to receive the selection condition further comprises:
program instructions to receive a conjunction of a first selection expression and a second selection expression, wherein the first selection expression comprises a first negation operator, and wherein the second selection expression comprises a second negation operator; and
program instructions to determine a skipped portion of the data blocks, wherein the skipped portion of the data blocks comprises selecting common data blocks of a first negative subset of data blocks and selecting common data blocks of a second negative subset of data blocks.

3. The computer program product of claim 1 , wherein the program instructions to receive the selection condition further comprises:
program instructions to receive a conjunction of a first selection expression and a second selection expression, wherein the first selection expression comprises a positive operator, and wherein the second selection expression comprises a first negative; and
program instructions to determine the skipped portion of the data blocks, wherein the skipped portion of the data blocks comprises a first negative subset of data blocks.

4. The computer program product of claim 1 , wherein the program instructions to receive the selection condition further comprises:
program instructions to receive a disjunction of a first selection expression and a second selection expression, wherein the first selection expression comprises a first negation operator, and wherein the second selection expression comprises a second negation operator; and
program instructions to determine the skipped portion of the data blocks, wherein the skipped portion of the data blocks comprises first negative subset of data blocks and the second negative subset of data blocks.

5. The computer program product of claim 1 , wherein the program instructions to receive the selection condition further comprises:
program instructions to receive a conjunction of a first selection expression and a second selection expression, wherein the first selection expression comprises a positive operator, and wherein the second selection expression comprises a first negative; and
program instructions to determine the skipped portion of the data blocks, wherein the skipped portion of the data blocks comprises the second negative subset of data blocks.

6. The computer program product of claim 1 , wherein the program instructions to generate the attribute value information further comprises:
program instructions to generate a multi-dimensional data structure, wherein the multi-dimensional data structure represents the set of data blocks; and
program instructions to add a data element, for each data block of the set of data blocks, into the multi-dimensional data structure, wherein the data element comprises multiple values associated with the attribute.

7. A computer system comprising:
one or more computer processors;
one or more computer readable storage media;
program instructions stored on the one or more computer readable storage media for execution by at least one of the one or more processors, the program instructions comprising:
program instructions to receive a set of data blocks and a query, wherein the set of data blocks comprises at least one attribute and, wherein the query specifies a selection condition on the at least one attribute, wherein the selection condition comprises at least one selection expression;
program instructions to generate an attribute value information on the at least one attribute, for each data block of the set of data blocks;
program instructions to generate a first condition on the at least one attribute, wherein the first condition negates each selection expression of the at least one selection expression, when the selection expression comprises a negation operator;
program instructions to generate a first set of conditions that comprises the generated first condition on the at least one attribute, and each of the at least one selection expression that does not comprise a negation operator;
program instructions to select a positive subset of data blocks, of the set of data blocks, for each condition of the first set of conditions, wherein the positive subset of data blocks, of the set of data blocks satisfies a condition of the first set of conditions, using the attribute value information;
program instructions to select a negative subset of data blocks, of the set of data blocks, for each condition of the first set of conditions, wherein the negative subset of data blocks, of the set of data blocks does not satisfies a condition of the first set of conditions, using the attribute value information;
program instructions to determine a skipped portion of the negative subsets of the data blocks, using the selection condition, and a non-skipped portion of the negative subsets of the data blocks, using the selection condition; and
program instructions to generate result data, wherein the generated result data comprises:
program instructions to process the positive subset of the data blocks; and
program instructions to process the negative portion non-skipped portion of the negative subsets of the data blocks.

8. The computer system of claim 7 , wherein the program instructions to receive the selection condition further comprises:
program instructions to receive a conjunction of a first selection expression and a second selection expressi

Assignees

• IBM

Inventors

• Boehme Thomas F
• Brodt Andreas
• Martin Daniel
• Schiller Oliver

Classifications

• G06F16/278

  Data partitioning, e.g. horizontal or vertical partitioning · CPC title

• G06F16/2456 Primary

  Join operations · CPC title

• G06F16/24537

  of operators · CPC title

• G06F16/248 Primary

  Presentation of query results · CPC title

• G06F17/30454

  Physics · mapped topic