title: Probability of collision when using a 32 bit hash
body: <p>I have a 10 character string key field in a database. I've used CRC32 to hash this field but I'm worry about duplicates. Could somebody show me the probability of collision in this situation?</p>
  
  <p>p.s. my string field is unique in the database. If the number of string fields is 1 million, what is probability of collision ?</p>