Is there an expression that returns TRUE if all the elements of a PostgreSQL array are NULL?
If it was a value other than NULL, I could of course use something like:
SELECT 4 = ALL (ARRAY[4,5]::integer[]);
However I want to do the ALL operation with an IS NULL test, rather than a = 4 test. I don't think there's an ALL syntax for this, and the semantics around NULL are compounded with arrays I've not myself been able to think of a form that achieves it. Hence my asking Stack Overflow. ;-)
I know I could write a function in pl/sql or pl/pgsql that does this, but I'd like to see if there's a direct expression before resorting to that.