Jeff Moden (8/9/2009)
Paul White (8/8/2009)
HashBytes (perhaps including the PK as a salt) is a good choice if the task is to detect changes.CHECKSUM is quick and efficient for creating hash indexes - which are awesome if you need to search long strings (for example).
Even then, it can and will give an incorrect answer if you rely only on it. I'll admit that CHECKSUM will help narrow things down on long strings, though.
I'm, going to have to disagree with this one, Jeff, at least as far as HashBytes using the SHA1 algorithm is concerned. Assuming you did a Trillion HashByte comparisons of different data a day (and no one on earth is doing that many), it would still take about 6000 to 12000 Years before you were likely to get an accidental match. Those are odds that I can live with. 🙂
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