System and method for automating implementation and execution of constraint most likely to be violated in a database

• US 5,488,722 A
• Filed: 05/28/1993
• Issued: 01/30/1996
• Est. Priority Date: 05/28/1993
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Potok, Thomas E.
• Primary Examiner(s): Kulik, Paul V.
• Application Number:
  US08/068,820
• Time in Patent Office: 977 Days
• Field of Search: 395/600, 395/700
• US Class Current: 717/106
• CPC Class Codes: G06F 16/288 Entity relationship models
• CPC Class Codes: Y10S 707/962 Entity-attribute-value
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing

Abstract

Disclosed is a system and method of operating a computer to update a database. An entry made by a user for creating, deleting or modifying an entity type instance is checked to determine applicable constraints, which are then activated and placed in a pool. A firing order is then determined for the activated constraints. The first ranked constraint is then coded, using database calls if necessary to provide data for the logical statements, after which the coded constraint is fired. If the constraint was violated an error is signalled and processing is returned to the step of activating constraints for treatment of revised user data. Otherwise, it is determined if any constraints remain to be fired before returning to the step of activating or exiting.

Claims

1. A method for operating a computer to update an entity-relationship model database, the method comprising the steps performed by the computer of:

accepting data for a new or modified instance or to delete an instance of an entity;

activating constraints applicable to the accepted data;

determining a firing order including at least a first constraint for firing from among the activated constraints, the first constraint being determined based on criteria which attempts to identify a constraint most likely to be violated;

firing the first constraint;

determining if the first constraint was violated; and

returning to the step of activating constraints if any constraints remain to be fired.

2. A method as set forth in claim 1, wherein the step of determining a firing order for the activated constraints includes:

finding a set of least recently fired constraints and if only one constraint is least recently fired making the constraint first in the firing order;

if a plurality of activated constraints are found for the set of least recently fired constraints, finding which constraints within the set of least recently fired constraints reference the greatest number of entity instances and if only one constraint references the greatest number of entity instances making the constraint first in the firing order; and

if a plurality of activated constraints reference the greatest number of entity and relationship instances, scoring the activated constraints for complexity and make a highest scoring constraint first in the firing order.

3. A method as set forth in claim 1, wherein the step of firing a first constraint in the firing order includes:

generating code for the first constraint;

generating code for inquiries into the database to complete inputs to the first constraint; and

executing the generated code.

4. A method as set forth in claim 2, wherein the step of firing a first constraint in the firing order includes:

generating code for the first constraint;

generating code for inquiries into the database to complete inputs to the first constraint; and

executing the generated code.

5. A method as set forth in claim 1, and further comprising:

logging violations of a constraint as error.

6. A method as set forth in claim 1, wherein the step of determining a firing order includes:

predicting a constraint from the activated constraint as most likely to be violated; and

selecting the predicted constraint for the firing step.

7. A constraint enforcement apparatus for an entity-reference model database on a data processing system, comprising:

user input means for requesting modification, creation or deletion of entity type instances in the database;

a plurality of constraints resident in a system storage;

means for activating constraints applicable to user input requests;

means for selecting a constraint for firing from among the activated constraints, said selecting means comprising means for predicting a constraint from the activated constraints as most likely to be violated and means for selecting the predicted constraint as first to be fired;

means for firing the constraint; and

means for determining if the constraint was violated.

8. Apparatus as set forth in claim 7, wherein the means for selecting a constraint for firing includes:

means for finding a set of least recently fired constraints and, if only one constraint is least recently fired, for making the least recently fired constraint first in a firing order;

means responsive to location of a plurality of least recently fired constraints for finding constraints within the set of least recently fired constraints which reference a greatest number of entity instances;

means responsive to finding of one constraint with the greatest number of entity instances for making the one constraint first in the firing order; and

means responsive to finding a plurality of activated constraints which reference the greatest number of entity instances for scoring each of the constraints referencing the greatest number of entity instances for complexity and for making a highest scoring constraint first in the firing order.

9. Apparatus as set forth in claim 7, wherein the means for firing the constraint include:

means for coding the constraint;

means for coding inquiries into the database to provide values for variables in the constraint; and

means for executing the code.

10. Apparatus as set forth in claim 8, wherein the means for firing the constraint includes:

generating code for the highest scoring constraint;

generating code for inquiries into the database to provide values for variables in the highest scoring constraint; and

executing the generated code.

11. Apparatus as set forth in claim 9, wherein the step of selecting a constraint for firing includes:

means for finding a set of least recently fired constraints and if only one constraint is least recently fired for making the least recently fired constraint first in a firing order;

means responsive to location of a plurality of least recently fired constraints for finding constraints within the set of least recently fired constraints which reference a greatest number of entity instances;

means responsive to finding of one constraint with the greatest number of entity instances for making the one constraint first in the firing order; and

means responsive to finding a plurality of activated constraints which reference the greatest number of entity and relationship instances for scoring the activated constraints for complexity and for making a highest scoring constraint first in the firing order.

12. Apparatus as set forth in claim 7, and further comprising:

means for logging violations of a constraint as error.