Accurate and timely enforcement of system resource allocation rules

A computer-implemented apparatus for optimizing a database query in a computer system, comprising:

• means, performed by the computer system, for generating a query execution plan for the database query using estimated cost information;
• means, performed by the computer system, for executing one or more steps of the query execution plan to retrieve data from a database stored on the computer system;
• means, performed by the computer system, for generating actual cost information for each of the executed steps;
• means, performed by the computer system, for re-calculating the estimated cost information using the actual cost information;
• and
• means, performed by the computer system, for executing one or more resource allocation rules based on the re-calculated estimated cost information.

An article of manufacture comprising one or more storage devices tangibly embodying instructions that, when executed by a computer system, result in the computer system performing a method for optimizing a database query, the method comprising:

• generating, in the computer system, a query execution plan for the database query using estimated cost information;
• executing, in the computer system, one or more steps of the query execution plan to retrieve data from a database stored on the computer system;
• generating, in the computer system, actual cost information for each of the executed steps;
• re-calculating, in the computer system, the estimated cost information using the actual cost information;
• and
• executing, in the computer system, one or more resource allocation rules based on the re-calculated estimated cost information.