It is not possible to ALTER a global variable, it is necessary to do DROP + re-CREATE it. And previously we must DROP all the objects that depends on it: PROCEDURE, FUNCTION, TRIGGER, VIEWS ..., and the packages are marked as invalid.
After having re-CREATE the global variable, we must create again all: PROCEDURE, FUNCTION, TRIGGER and VIEWS. And rebind the packages afected.
All this causes the unavailability of affected applications. And it is very, very disruptive.
So, we need an Alter VARIABLE command to change the properties of the variables, at least the initial Default value for exemple.
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