Database views A database view defines table joins for reporting purposes. For example, a database view can join the Incident table to the Metric Definition and Metric Instance tables. This view can be used to report on incident metrics and may include fields from any of these three tables. A number of useful database views are installed with the Database View plugin and the Database Views for Service Management plugin. These database views cover most metric reporting needs and greatly reduce the need to define new ones. Note: In general, as the number of tables that are included in the view and the number of records that those tables contain increases, the accumulated impact on performance grows. In addition, to optimize the performance of the database view ensure that the ‘where’ clauses that are defined in the database view are based on indexed fields. Limitations Database views cannot be created on tables that participate in table rotation. It is not possible to edit data within a database view. ACLs and database views You do not need to create ACLs on fields in the view. The system honors contextual ACLs (ACLs with a condition or script) that already exist on the underlying table. Non-contextual ACLs (ACLs with only role checks) are still honored just as with previous releases. You can revert this functionality to legacy behavior and require explicit read ACLs to be added to the database views. Set the glide.security.expander.view.legacy property to true. For upgraded instances, add this property to the system, and set it to true for the same legacy behavior in pre-Istanbul releases, or set to false to use the new behavior. You can still create additional ACLs on the database views. These ACLs are evaluated last and are always honored. Database view reserved words Using the terms may cause unintended or undesirable performance. For more information, see the MySQL reserved words document.