It's a good idea. However, it's not that easy as with ORA_MAX_NAME_LEN, because you would need to recompile all PL/SQL code after changing to EXTENDED. - A package holding the constant would be good enough. Change the value manually or by a generator would enforce recompilation of the affected code.
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My memory just thought that because changing to EXTENDED is not simply setting the parameter - there's a procedure to follow and a database restart - then this procedure *could* have taken care of invalidation too.
I'll do a package constant, no worries.