Changing the Max Item Number is straightforward if the entity is not "InUse", as in, there isn't any BOARD infocube version structured by that dimension (please refer to the ENTITY design tab in the Database section of the Windows Client)
Applying the Max Item Number change, to an entity which is used at least in one infocube version, requires it to be cleared. This consequently causes the data loss of all the infocube versions structured by that entity.
You might also want to check this article about deleting entity elements, and its consequences when clearing an entity
A very simple (yet safe) procedure to change the entity Max item Number that does not require you to clear the entity is to:
- Run an "Extract all cubes" action
- Clear cubes
- Change your MaxitemNo
- Run the "Import all cubes" action