Direct call threaded code

• US 7,392,245 B1
• Filed: 07/28/2000
• Issued: 06/24/2008
• Est. Priority Date: 07/30/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Doole, Douglas James, Finlay, Ian R.
• Primary Examiner(s): Breene; John
• Assistant Examiner(s): Ly; Anh
• Application Number:
  US09/628,599
• Time in Patent Office: 2,888 Days
• Field of Search: 707 1- 10, 707/100, 717/141, 717/129
• US Class Current: 1/1
• CPC Class Codes: G06F 16/24524 Access plan code generation and invalidation; Reuse of access plans
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99934 Query formulation, input preparation, or translation
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A pre-pass and direct call mechanism which replaces the interpreter. The mechanism moves static decisions out of the repeated runtime path into a pre-pass operation. Advantageously, the mechanism reduces runtime overhead and improves overall performance of the DBMS during runtime, while maintaining the considerable investment in opcode generation and plan representation.

Claims

1. A method for pre-processing an access plan generated for a query in a relational database management system to include a direct call mechanism replacing a lookup function of a run-time interpreter, said access plan including a plurality of operation codes, each of said operation codes being associated with one or more executable functions for performing the query, said method comprising the steps of:

(a) determining from the access plan an executable function associated with a first operation code; and

(b) augmenting said first operation code in the access plan with a pointer to said executable function to provide a direct call mechanism replacing a lookup function of a run-time interpreter.

2. The method as claimed in claim 1, further comprising repeating steps (a) and (b) for the remaining operation codes in the access plan.

3. The method as claimed in claim 1, wherein said step (b) comprises augmenting said first operation code in the access plan with a pointer to an intermediate function, said intermediate function including a data structure for storing a pointer to said executable function.

4. The method as claimed in claim 3, wherein said data structure includes means for storing information associated with said executable function or said first operation code.

5. The method as claimed in claim 1, wherein said step (b) comprises augmenting said first operation code in the access plan with another pointer to a data structure, said data structure providing means for storing information associated with said first operation code or said executable function.

6. The method as claimed in claim 1, further comprising a step of assessing the executable function associated with the first operation code and if applicable, replacing the call to the executable function with a call to a second executable function.

7. The method as claimed in claim 3, wherein said intermediate function includes processing operations for the first operation code or the executable function associated with the first operation code.

8. The method as claimed in claim 7, wherein said processing operations in the intermediate function includes gathering statistics on the use of the executable function associated with the first operation code.

9. The method as claimed in claim 7, wherein said processing operations in the intermediate function includes a pause for receiving user input before or after the call to the executable function.