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Bug in POWER function?


Bug in POWER function?

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jon-230788
jon-230788
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I was just trying to load up the largest BIGINT, 9,223,372,036,854,775,807, by using the POWER function (2^63) - 1. When plugging in "2 raised to the 63," the returned value is 9,223,372,036,854,775,800 and not 9,223,372,036,854,775,808 as I would expect (prior subtracting 1 to get the largest allowed BIGINT).

SELECT POWER(2., 63.) - 1.

When obtaining the largest INT value by raising to the power of 31, I get the expected results.

SELECT POWER(2., 31.) - 1.

This a known issue?
GSquared
GSquared
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It's probably a floating point issue. It looks like you're using floating point numbers (they have decimal places), instead of integers. Shouldn't affect whole-number calculations, but it may in this kind of case.

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Jeff Moden
Jeff Moden
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POWER relies on a FLOAT conversion which, IIRC, has a maximum precision of 15 digits. Here's an article that demonstrates the problem for another function that does a FLOAT conversion...
http://www.sqlservercentral.com/articles/T-SQL/71565/



--Jeff Moden

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Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.
Although they tell us that they want it real bad, our primary goal is to ensure that we dont actually give it to them that way.
Although change is inevitable, change for the better is not.
Just because you can do something in PowerShell, doesnt mean you should. Wink

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