ZDIFFSTORE destination numkeys key [key ...]
Available since: 6.2.0
Time complexity: O(L + (N-K)log(N)) worst case where L is the total number of elements in all the sets, N is the size of the first set, and K is the size of the result set.
ACL categories:
@write
@sortedset
@slow
Computes the difference between the first and all successive input sorted sets
and stores the result in destination. The total number of input keys is
specified by numkeys.
Keys that do not exist are considered to be empty sets.
If destination already exists, it is overwritten.
Return
Integer reply: the number of elements in the resulting sorted set at
destination.