| 摘要 |
A method, computer program, and database system are disclosed for executing database queries. The database includes 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). One implementation of the method includes preparing a database query for execution based at least in part on application of a derived constraint rule (DCR) having the form, (PK=FK)→CV2+C1≰CV1≰CV2+C2, where C1 and C2 are constants and“→”means“implies,”to produce an execution plan. A frequency of errors due to changes in DCRs is taken into account when preparing the execution plan. The plan is then executed.
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