Efficient division by 128, in tsql

As part of implementing a half-life behaviour, I need to perform x =开发者_开发知识库 x - x / 128 on around a hundred thousand rows every few days. Is tsql smart enough to do the division by 128 efficiently (as a bit-shift), or is it just as efficient to divide by 130?

If tsql isn't smart enough, is there anything clever that I can do to make it more efficient?

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A hundred thousand rows isn't enough that the difference in perf between a divide operation and a shift operation would probably even be measurable. Especially if you only have to do it every few days. Better to spend your time worrying about other issues.

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You could use a computed column with the PERSISTED flag to ensure that the values were physically stored and not recomputed every time they were displayed. That could (possibly, depending on your particular circumstances) be more efficient.

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More liklely you will have problems with integer math. I don't know what your x values are but if they are also integers, you want to divide by 128.0 if you don;t want the answer to be rounded to the nearest integer.