The previous section covered the process of validating a table as defined in the metadata with the physical table as defined in the database. If a table is found to be different it is possible to alter the table.
Caution should be taken when altering large data warehouse tables. Several factors such as the time required to perform the alter, access to the table and the optimum storage of the table come into play.
To alter a table, first validate the table through the Validate > Validate Table Create Status menu option, or use the right-click menu option from the object name. Then in the middle pane (the validation listing) right-click the table that has not been validated and select Alter table. A screen similar to the one below appears advising of the planned changes.
In this example, the dim_product table is to be altered. Comments at the top of the screen, show the reason(s) for the alteration and the actual alter command(s) follow.
The alter table window is an edit window. The command to be executed can be changed or additional commands entered. The command may also be cut to be executed in some other environment or at some later stage.
Clicking the Alter Table button alters the table. In effect, it will execute any command in the window.