System and method for improving query response time in a relational database (RDB) system by managing the number of unique table aliases defined within an RDB-specific search expression

• US 20060195427A1
• Filed: 12/27/2005
• Published: 08/31/2006
• Est. Priority Date: 02/25/2005
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Kilroy, John F.
• Application Number:
  US11/318,915
• Publication Number:
  US 20060195427A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2454 Optimisation of common expressions

Abstract

Described are a system and method for searching a relational database. An expression tree, representing a string-based search expression, has a logical node with a first child node and a second child node. Each child node represents a sub-expression of the search expression. The logical node represents a logical operator used to combine the sub-expressions represented by the children nodes. An attribute in the sub-expression of the first child node is determined to have a same data type and to be associated with the same table in a relational database as an attribute in the sub-expression of the second child node. A table alias is associated with the table. A sub-query expression is generated based on the sub-expressions of the children nodes and on the logical operator of the logical node. The sub-query expression is part of a repository-specific query expression to be used to query the relational database. The sub-query expression uses the table alias in a translation of the sub-expression of the first child node and the same table alias in a translation of the sub-expression of the second child node if the logical node is a logical OR operator.

Claims

1. A computerized method for performing a search of a relational database, the method comprising:

providing an expression tree representing a string-based search expression, the expression tree having a plurality of nodes including a logical node, the logical node of the expression tree having a first child node and a second child node, each child node representing a sub-expression of the string-based search expression, the logical node representing a logical operator used to combine the sub-expressions represented by the children nodes of the logical node;

determining that an attribute in the sub-expression of the first child node of the logical node has a same data type and is associated with the same table in a relational database as an attribute in the sub-expression of the second child node of the logical node;

associating a table alias with the table; and

generating a sub-query expression based on the sub-expressions of the children nodes and on the logical operator of the logical node, the sub-query expression being part of a repository-specific query expression to be used to query the relational database, the sub-query expression using the table alias in a translation of the sub-expression of the first child node and the same table alias in a translation of the sub-expression of the second child node if the logical node is a logical OR operator.

2. The method of claim 1, further comprising the step of associating the table with a different second table alias for use in the translation of the sub-expression of the second child node if the logical node is a logical AND operator.

3. The method of claim 2, further comprising the step of reusing a table alias currently included in the sub-query expression for the second table alias that is used in the translation of the sub-expression of the second child node.

4. The method of claim 2, further comprising the step of adding the second table alias to the sub-query expression if the second table alias is new to the sub-query expression.

5. The method of claim 1, further comprising the step of completely generating the repository-specific query expression in a single traversal of the expression tree.

6. The method of claim 1, wherein the step of determining occurs upon traversing to the second child node of the logical node.

7. A computerized system for performing a search of a relational database, the system comprising:

a parser producing an expression tree from a string-based search expression, the expression tree having a plurality of nodes including a logical node, the logical node of the expression tree having a first child node and a second child node, each child node representing a sub-expression of the string-based search expression, the logical node representing a logical operator used to combine the sub-expressions represented by the children nodes of the logical node; and

an adapter receiving the expression tree and determining that an attribute in the sub-expression of the first child node of the logical node has a same data type and is associated with the same table in a relational database as an attribute in the sub-expression of the second child node of the logical node, the adapter associating a table alias with the table and generating a sub-query expression based on the sub-expressions of the children nodes and on the logical operator of the logical node, the sub-query expression being part of a repository-specific query expression to be used to query the relational database, the sub-query expression using the table alias in a translation of the sub-expression of the first child node and the same table alias in a translation of the sub-expression of the second child node if the logical node is a logical OR operator.

8. The system of claim of claim 7, wherein the adapter associates the table with a different second table alias for use in the translation of the sub-expression of the second child node if the logical node is a logical AND operator.

9. The system of claim of claim 8, wherein the adapter reuses a table alias currently included in the sub-query expression for the second table alias that is used in the translation of the sub-expression of the second child node.

10. The system of claim of claim 8, wherein the adapter adds the second table alias to the sub-query expression if the second table alias is new to the sub-query expression.

11. The system of claim of claim 7, wherein the adapter completely generates the repository-specific query expression in a single traversal of the expression tree.

12. A computer program product for use with a computer system, the computer program product comprising a computer useable medium having embodied therein program code comprising:

program code for providing an expression tree representing a string-based search expression, the expression tree having a plurality of nodes including a logical node, the logical node of the expression tree having a first child node and a second child node, each child node representing a sub-expression of the string-based search expression, the logical node representing a logical operator used to combine the sub-expressions represented by the children nodes of the logical node;

program code for determining that an attribute in the sub-expression of the first child node of the logical node has a same data type and is associated with the same table in a relational database as an attribute in the sub-expression of the second child node of the logical node;

program code for associating a table alias with the table; and

program code for generating a sub-query expression based on the sub-expressions of the children nodes and on the logical operator of the logical node, the sub-query expression being part of a repository-specific query expression to be used to query the relational database, the sub-query expression using the table alias in a translation of the sub-expression of the first child node and the same table alias in a translation of the sub-expression of the second child node if the logical node is a logical OR operator.

13. The computer program product of claim 12, further comprising program code for associating the table with a different second table alias for use in the translation of the sub-expression of the second child node if the logical node is a logical AND operator.

14. The computer program product of claim 13, further comprising program code for reusing a table alias currently included in the sub-query expression for the second table alias that is used in the translation of the sub-expression of the second child node.

15. The computer program product of claim 13, further comprising program code for adding the second table alias to the sub-query expression if the second table alias is new to the sub-query expression.

16. The computer program product of claim 12, further comprising program code for completely generating the repository-specific query expression in a single traversal of the expression tree.

17. A computer data signal embodied in a carrier wave for use with a computer system having a display and capable of generating a user interface through which a user may interact with the computer system, the computer data signal comprising:

program code for providing an expression tree representing a string-based search expression, the expression tree having a plurality of nodes including a logical node, the logical node of the expression tree having a first child node and a second child node, each child node representing a sub-expression of the string-based search expression, the logical node representing a logical operator used to combine the sub-expressions represented by the children nodes of the logical node;

program code for determining that an attribute in the sub-expression of the first child node of the logical node has a same data type and is associated with the same table in a relational database as an attribute in the sub-expression of the second child node of the logical node;

program code for associating a table alias with the table; and

program code for generating a sub-query expression based on the sub-expressions of the children nodes and on the logical operator of the logical node, the sub-query expression being part of a repository-specific query expression to be used to query the relational database, the sub-query expression using the table alias in a translation of the sub-expression of the first child node and the same table alias in a translation of the sub-expression of the second child node if the logical node is a logical OR operator.

18. The computer data signal of claim 17, further comprising program code for associating the table with a different second table alias for use in the translation of the sub-expression of the second child node if the logical node is a logical AND operator.

19. The computer data signal of claim 18, further comprising program code for reusing a table alias currently included in the sub-query expression for the second table alias that is used in the translation of the sub-expression of the second child node.

20. The computer data signal of claim 18, further comprising program code for adding the second table alias to the sub-query expression if the second table alias is new to the sub-query expression.

21. The computer data signal of claim 17, further comprising program code for completely generating the repository-specific query expression in a single traversal of the expression tree.