HASH function as a Uniqe number generator

eli_revach

Hi 
We like to use Vertica HASH() function, for generating numbers on top of scripts , did  HASH function gurenty Uniqes ? so  two diffrent string will never have the same same hash number ?.

Daniel_Leybovic

>> did  HASH function gurenty Uniqes ?
No.

Hash
Calculates a hash value over its arguments, producing a value in the range 0 <= x < 2^63.

So uniqueness not guaranteed, in sequence 0 <= Seq <= 2^63 + 1 must be exists at least one duplicate.
Pigeonhole principle: http://en.wikipedia.org/wiki/Pigeonhole_principle

eli_revach

I agree ,i more ask about vertica imlemention