Of course if you have multiple severs or may reboot you need to store the salt somewhere. If you are going to bother storing the salt and cleaning it up after t

Of course if you have multiple severs or may reboot you need to store the salt somewhere. If you are going to bother storing the salt and cleaning it up after the day is over it may be just as easy to clean the hashes at the end of the day (and keep the total count) which is equivalent. This should work unless you want to keep individual counts around for something like seeing distribution of requests per IP or similar. But in that case you could just replace the hashes with random values at the end of the day to fully anonymize them since you no longer need to increment then.