Patent ID: 7672926
Filing Date: 2010-03-02
Classification: G06F,Y10S

Abstract:
1. A method for executing database queries, the database comprising a first table (T1) having a primary key (PK) column and a first correlated value column (CV1) and a second table (T2) having a foreign key (FK) column related to the primary key column of the first table and a second correlated value column (CV2), comprising the steps of: preparing a database query for execution on a database comprising a first table (T1) having a primary key (PK) column and a first correlated value column (CV1) and a second table (T2) having a foreign key (FK) column related to the primary key column of the first table and a second correlated value column (CV2), said execution based at least in part on application of a derived constraint rule (DCR) having the following form: where C1 and C2 are constants, and “→” means “implies,” to produce an execution plan; taking into account a frequency of errors due to changes in DCRs when preparing the execution plan, wherein taking into account the frequency of errors due to changes in DCRs when preparing the execution plan comprises determining that a higher cost execution plan that risks no errors due to changes in DCRs is preferable; and executing the plan.