Hash table collisions: why use a linked list if we can use a hash set?

One way to deal with the problem of collisions for a hash table is to have a linked list for each bucket. But then the lookup time is no longer constant. Why not use a hash set instead of a linked list? The lookup time would then be constant. For example, in C++ the hash table could be defined as:

unordered_map> m;

An hash set is an hash table. Using an hash set to handle collisions in an hash table is equivalent to using a bigger hash table, with an hashing function which is a combination of the hashing functions of both level.

In other words, you'd probably be better with a bigger initial table (for instance there is no risk of resonance between the two hash functions which could lead to an higher collision rate than expected at the second level).

StackExchange Computer Science Q#51230, answer score: 8