How is the storage of keys longer than 128 bytes implemented in a map structure?

In Go, the map structure is implemented as a hash table where keys are stored as values. If a key exceeds 128 bytes in length, a pointer to the key is used for optimization and to reduce copying costs, rather than the entire key itself.

That is, when adding a long key to a map, Go stores not the key itself but a reference to the memory area where the key is located. This helps avoid excessive copying of large data and speeds up map operations.

Thus, for keys longer than 128 bytes, the map stores a pointer to the key rather than the key itself, which optimizes memory usage and performance.