Presented is a method to perform a query to retrieve data from a database that is part of a computer system comprising a Data-Base Management System (DBMS) with an optimizer. A Query Execution Plan (QEP) is generated for the query. The QEP is assessed by considering statistical values about previous executions of the query according to the QEP to decide whether to choose the QEP or to generate a new QEP. Furthermore, the statistical values on previous executions of the query are exploited during query optimization. The query is executed according to the chosen QEP. For optimizing the execution of future queries, statistical values about the execution of the query are collected during execution.