A computer-implemented database online reorganization method for dynamically adapting a database layout of a database containing tables, wherein the tables are vertically partitioned into containers, each container containing one or more attributes of one table, the method comprising: analyzing, by a workload analysis tool of a computer system, a workload on a set of tables of the database, the workload comprising queries; detecting, by the workload analysis tool of the computer system, a workload change of the workload; analyzing, by a workload evaluation tool of the computer system, if a new layout for the set of tables is considered optimal in view of the workload change; and deciding, by the workload evaluation tool of the computer system, whether the layout of the set of tables is switched to the new layout, wherein deciding whether the layout of the set of tables is switched to the new layout comprises: determining the workload costs of the current layout, the workload costs of the layout that is considered optimal in view of the workload change, and the penalty costs as the difference between the workload costs of the current layout and the workload costs of the layout that is considered optimal in view of the workload change; determining the transition costs for changing the current layout to the layout that is considered optimal in view of the workload change; determining weighted penalty costs by multiplying the penalty costs with a weight factor; determining new accumulated penalty costs by adding the weighted penalty costs to previously accumulated penalty costs; and triggering the switching of the layout of the set of tables from the current layout to the layout that is considered optimal in view of the workload change if the new accumulated penalty costs is larger than the transition costs. analyzing, by a workload analysis tool of a computer system, a workload on a set of tables of the database, the workload comprising queries; detecting, by the workload analysis tool of the computer system, a workload change of the workload; analyzing, by a workload evaluation tool of the computer system, if a new layout for the set of tables is considered optimal in view of the workload change; and deciding, by the workload evaluation tool of the computer system, whether the layout of the set of tables is switched to the new layout, determining the workload costs of the current layout, the workload costs of the layout that is considered optimal in view of the workload change, and the penalty costs as the difference between the workload costs of the current layout and the workload costs of the layout that is considered optimal in view of the workload change; determining the transition costs for changing the current layout to the layout that is considered optimal in view of the workload change; determining weighted penalty costs by multiplying the penalty costs with a weight factor; determining new accumulated penalty costs by adding the weighted penalty costs to previously accumulated penalty costs; and triggering the switching of the layout of the set of tables from the current layout to the layout that is considered optimal in view of the workload change if the new accumulated penalty costs is larger than the transition costs. <EOS>