Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1999-06-02
2002-04-16
Black, Thomas (Department: 2171)
Data processing: database and file management or data structures
Database design
Data structure types
C709S241000, C709S223000
Reexamination Certificate
active
06374233
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an apparatus and method for processing data.
Data processing frequently involves the evaluation of expressions, formed by combining operand values and operators according to defined rules of syntax. For example, the expression
(A and B) or (not C) involves operand values A, B and C and logical operators “and”, “or” and “not”. The evaluation of an expression returns a result value, which in the above example will be either “true” or “false”.
In many data processing applications, the length of time taken to acquire an operand value cannot be predicted. In some cases, a value may be available in milliseconds (for example where it is already held in cache memory) while in other cases it may take weeks (for example, where information from a customer has to be obtained by post).
The object of the present invention is to provide a novel apparatus and method for efficiently handling expressions which are subject to such unpredictability.
SUMMARY OF THE INVENTION
According to the invention a data processing method comprises:
(a) issuing parallel requests to acquire a plurality of operands for evaluating an expression,
(b) detecting, upon receipt of a first subset of the operands, whether a second subset of the operands is still required to evaluate the expression, and
(c) if the second subset is no longer required, cancelling the request for the second subset.
The invention also includes data processing apparatus for performing this method.
REFERENCES:
patent: 5283856 (1994-02-01), Gross et al.
patent: 5485612 (1996-01-01), Ota et al.
patent: 5668984 (1997-09-01), Taborn et al.
patent: 5832224 (1998-11-01), Fehskens et al.
patent: 6205441 (2001-03-01), Al-omari et al.
Black Thomas
Chen Te Yu
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