System, method and computer program product for host variable support

• US 6,360,225 B1
• Filed: 09/25/1997
• Issued: 03/19/2002
• Est. Priority Date: 09/29/1994
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wang, Yun, Kleewein, James C., Lin, Eileen T.
• Primary Examiner(s): HOMERE, JEAN RAYMOND
• Application Number:
  US08/937,363
• Time in Patent Office: 1,636 Days
• Field of Search: 707/10, 707/4, 707/102, 707/201, 395/200.31, 395/200.47, 395/200.53
• US Class Current: 1/1
• CPC Class Codes: G06F 16/256 in federated or virtual databases
• CPC Class Codes: Y10S 707/99934 Query formulation, input preparation, or translation
• CPC Class Codes: Y10S 707/99939 Privileged access
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A system, method and computer program product for providing a common interface to a plurality of heterogeneous database management systems, wherein data associated with a client is distributed among the plurality of heterogeneous database management systems. The system simulates support of host variables in any of the heterogeneous database management systems which does not support host variables.

Claims

1. A method for providing a common interface for submitting database statements to a plurality of heterogeneous database management systems, wherein data associated with a client is distributed among said plurality of heterogeneous database management systems, comprising the steps of:

(a) simulating support of host variables in database statements submitted to any of said heterogeneous management systems which does not support host variables, by;

(1) determining whether a host variable referenced in a database statement issued by said client is invariant between statements;

(2) if said host variable is invariant between statements, then replacing in said database statement said host variable with a literal value of said host variable;

(3) if said host variable is not invariant between statements, then determining whether said host variable is invariant within a loop iteration; and

(4) if said host variable is invariant within a loop iteration, then replacing in said database statement said host variable with a literal value of said host variable during each loop iteration.

2. A method for providing a common interface for submitting database statements to a plurality of heterogeneous database management systems, wherein data associated with a client is distributed among said plurality of heterogeneous database management systems, comprising the step of:

(1) simulating support of host variables in database statements submitted to any of said heterogeneous management systems which does not support host variables, wherein said step (1) comprises the steps of;

(a) determining whether a host variable referenced in a database statement issued by said client is invariant between statements; and

(b) if said host variable is invariant between statements, then replacing in said database statement said host variable with a literal value of said host variable.

3. A method for providing a common interface for submitting database statements to a plurality of heterogeneous database management systems, wherein data associated with a client is distributed among said plurality of heterogeneous database management systems, comprising the step of:

(1) simulating support of host variables in database statements submitted to any of said heterogeneous management systems which does not support host variables, wherein said step (1) comprises the steps of;

(a) determining whether a host variable referenced in a database statement issued by said client is invariant between statements;

(b) if said host variable is not invariant between statements, then determining whether said host variable is invariant within a loop iteration; and

(c) if said host variable is invariant within a loop iteration, then replacing in said database statement said host variable with a literal value of said host variable during each loop iteration.

4. A system for providing a common interface for submitting database statements to a plurality of heterogeneous database management systems, wherein data associated with a client is distributed among said plurality of heterogeneous database management systems, comprising:

an interface module that simulates support of host variables in database statements submitted to any of said heterogeneous database management systems which does not support host variables, including;

means for determining whether a host variable referenced in a database statement issued by said client is invariant between statements;

means for replacing in said database statement said host variable with a literal value of said host variable, if said host variable is invariant between statements;

means for determining whether said host variable is invariant within a loop iteration, if said host variable is not invariant between statements; and

means for replacing in said database statement said host variable with a literal value of said host variable during each loop iteration, if said host variable is invariant within a loop iteration.

5. A system for providing a common interface for submitting database statements to a plurality of heterogeneous database management systems, wherein data associated with a client is distributed among said plurality of heterogeneous database management systems, comprising:

an interface module that simulates support of host variables in database statements submitted to any of said heterogeneous database management systems which does not support host variables, wherein said interface module comprises;

means for determining whether a host variable referenced in a database statement issued by said client is invariant between statements; and

means for replacing in said database statement said host variable with a literal value of said host variable, if said host variable is invariant between statements.

6. A system for providing a common interface for submitting database statements to a plurality of heterogeneous database management systems, wherein data associated with a client is distributed among said plurality of heterogeneous database management systems, comprising:

an interface module that simulates support of host variables in database statements submitted to any of said heterogeneous database management systems which does not support host variables, wherein said interface module comprises;

means for determining whether a host variable referenced in a database statement issued by said client is invariant between statements;

means for determining whether said host variable is invariant within a loop iteration, if said host variable is not invariant between statements; and

means for replacing in said database statement said host variable with a literal value of said host variable during each loop iteration, if said host variable is invariant within a loop iteration.

7. A computer program product for use with a computer system, said computer program product comprising:

a computer usable medium having computer readable program code means embodied in said medium for causing the computer system to provide a common interface for submitting database statements to a plurality of heterogeneous database management systems, wherein data associated with a client is distributed among said plurality of heterogeneous database management systems, said computer readable program code means comprising;

computer readable program code means for enabling the computer system to simulate support of host variables in database statements submitted to any of said heterogeneous database management systems which does not support host variables, including;

computer readable program code means for enabling the computer system to determine whether a host variable referenced in a database statement issued by said client is invariant between statements;

computer readable program code means for enabling the computer system to replace in said database statement said host variable with a literal value of said host variable, if said host variable is invariant between statements;

computer readable program code means for enabling the computer system to determine whether said host variable is invariant within a loop iteration, if said host variable is not invariant between statements; and

computer readable program code means for enabling the computer system to replace in said database statement said host variable with a literal value of said host variable during each loop iteration, if said host variable is invariant within a loop iteration.

8. A computer program product for use with a computer system, said computer program product comprising:

a computer usable medium having computer readable program code means embodied in said medium for causing the computer system to provide a common interface for submitting database statements to a plurality of heterogeneous database management systems, wherein data associated with a client is distributed among said plurality of heterogeneous database management systems, said computer readable program code means comprising;

first computer readable program code means for enabling the computer system to simulate support of host variables in database statements submitted to any of said heterogeneous database management systems which does not support host variables, wherein said first computer readable program code means comprises;

computer readable program code means for enabling the computer system to determine whether a host variable referenced in a database statement issued by said client is invariant between statements; and

computer readable program code means for enabling the computer system to replace in said database statement said host variable with a literal value of said host variable, if said host variable is invariant between statements.

9. A computer program product for use with a computer system, said computer program product comprising:

a computer usable medium having computer readable program code means embodied in said medium for causing the computer system to provide a common interface for submitting database statements to a plurality of heterogeneous database management systems, wherein data associated with a client is distributed among said plurality of heterogeneous database management systems, said computer readable program code means comprising;

first computer readable program code means for enabling the computer system to simulate support of host variables in database statements submitted to any of said heterogeneous database management systems which does not support host variables, wherein said first computer readable program code means further comprises;

computer readable program code means for enabling the computer system to determine whether a host variable referenced in a database statement issued by said client is invariant between statements;

computer readable program code means for enabling the computer system to determine whether said host variable is invariant within a loop iteration, if said host variable is not invariant between statements; and

computer readable program code means for enabling the computer system to replace in said database statement said host variable with a literal value of said host variable during each loop iteration, if said host variable is invariant within a loop iteration.