Curt Sampson wrote: > On Mon, 16 Feb 2003, Ryan Bradetich wrote: > > Since my only requirement is that the rows be unique, I have developed a > > custom MD5 function in C, and created an index on the MD5 hash of the > > concatanation of all the fields. > > Well, that won't guarantee uniqueness, since it's perfectly possible > to have two different rows hash to the same value. (If that weren't > possible, your hash would have to contain as much information as the row > itself, and your space savings wouldn't be nearly so dramatic.)
That's true, but even if he has 4 billion rows it drops the probability of a duplicate down to something like one in 4 billion, so it's probably a safe enough bet. His application doesn't require absolute uniqueness, fortunately, so md5 works well enough in this case. Otherwise md5 wouldn't be a terribly good hash... -- Kevin Brown [EMAIL PROTECTED] ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
