DATABASE QUERY PROCESSING METHOD AND SYSTEM

• US 20070244852A1
• Filed: 04/03/2007
• Published: 10/18/2007
• Est. Priority Date: 04/06/2006
• Status: Active Grant

• Current Assignee: LinkedIn Corporation (Microsoft Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Giulio, Domenico
• Granted Patent: US 7,797,312 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/90335 Query processing

Abstract

An approach to reuse of database query functions using a set of “intelligent” fetch functions, one for each object in the application, in such a way that each function is able to locate the right occurrence of the database table from which it must fetch the data, then fetching the related columns. The appropriate “fetch” function is then recursively invoked for each associated object. This way, the logic that implements fetching of data from the appropriate tables and creates the structures that result from execution of the query is not query-dependent, and can be reused for every SQL query in the application. Generic functions are instructed to locate the query-specific names used to alias database tables in specific SQL queries by defining, together with each SQL query, a “table path” for every table instance involved in the query, together with a mapping to the alias used for that instance. The alias of the right table from which a “fetch” function must fetch the data is found by executing a search over the set of “table paths”, looking for the table path corresponding to that invocation of the function. The “table path” describes a path including all the tables that are “touched” when navigating the join tree from the first table to be considered to the current one.

Claims

1. A method of interrogating a database comprising a plurality of tables, said method comprising the steps of:

generating a database query, and a data map, said data map describing the structure of table instances associated with said database query;

submitting said database query to said database;

receiving a response from said database;

traversing said data map so as to iteratively apply a data extraction process to components of said response corresponding to each table instance associated with said database query, thereby extracting required data from said response.

2. The method of claim 1 wherein said data map is a recursive data structure.

3. The method of claim 1 wherein said data map defines a tree structure.

4. The method of claim 3 wherein each node of said tree apart from the root node thereof has a label providing a table path section, and said root node has no such label, said method comprising the further steps of building a table path for a given node by concatenating the labels of the nodes found by traversing the tree from the root to said given node.

5. The method of claim 1 wherein there are defined a plurality of extraction processes from which said data extraction process is selected, each of said extraction processes being defined in correspondence with a particular information request.

6. The method of claim 5 wherein said plurality of extraction processes comprises a first extraction process concerning a first plurality of response components, and a second extraction process concerning a second plurality of response components, wherein said second plurality of response components is a subset of said first plurality of response components.

7. The method of claim 6 wherein said first plurality of response components comprises all components of a particular expected response.

8. The method of claim 5 comprising a further step of generating an extraction process identifier, said extraction process identifier identifying a selected one of said plurality of extraction processes to be applied to the results of said database query, and wherein said data extraction process is the extraction process identified by said extraction process identifier.

9. The method of claim 8 wherein said extraction process identifier is incorporated in said data map.

10. The method of claim 1 wherein each table instance is assigned an alias in said data query, and said data map provides a concordance between a position in the structure defined in said data map and an alias.

11. The method of claim 1 wherein said data map is generated with reference to said data query, and to the internal logic of said database.

12. A computer-implemented data structure comprising a data map stored in a computer memory describing the structure of table instances associated with a database query, wherein said data map provides a concordance between a position in the structure of said data map and an alias corresponding to each table instance implicated in said data query.

13. The data structure of claim 12 wherein said data map is a data tree comprising a node for each table instance associated with said database query, wherein the root of said tree has no label and each other node has a label providing a table path section, whereby a table path for a given node that can be built by concatenating the labels of the nodes found by traversing the tree from the root to that node, said label further providing said concordance between a position in the structure of said data map and an alias corresponding to each table instance implicated in said data query.

14. A computer program in a computer readable medium comprising instructions for carrying out the steps of the method when said computer program is executed on a computer, the method comprising the steps of:

generating a database query, and a data map, said data map describing the structure of table instances associated with said database query;

submitting said database query to said database;

receiving a response from said database;

traversing said data map so as to iteratively apply a data extraction process to components of said response corresponding to each table instance associated with said

database query, thereby extracting required data from said response.

15. The computer program according to claim 14 wherein the computer readable medium is a storage medium.

16. A system for interrogating a database comprising a plurality of tables, the system comprising:

means for generating a database query, and a data map, said data map describing the structure of table instances associated with said database query;

means for submitting said database query to said database;

means for receiving a response from said database;

means for traversing said data map so as to iteratively apply a data extraction process to components of said response corresponding to each table instance associated with said database query, thereby extracting required data from said response.