title: Where can I find xxhash64 and md5 collision probability statistics?
body: <p>I dont find any info about % of collisions for xxhash64.</p>
  
  <p>I'm going to use it for cache system (to generate hash keys which need to be unique, about a hundreds millions).
  Now i use md5, but i don't need cryptographic property.</p>
  
  <p>So i need some info, to decide does is it a good decision for my task.
  In best case - comparison of the number of collisions between md5 and xxHash64.</p>