So Bitcoin uses a 32 bit value nonce in the bitcoin header. This means that it takes about 4 billion hashes to run out of nonce values. There is also a timestamp in the Bitcoin header which is Unix time. This means that it only counts in seconds.
So if you get through all the nonce values for your current timestamp, you have to update the timestamp.
So if someone had a hash rate of over 4 billion hashes per second (4Gh), wouldn't you be mining too fast for there to be more things to hash?
How do miners overcome this issue? (I heard something about "rolling nonce" or "extra nonce", but I don't understand them)