On 11/20/2011 02:06 PM, Tom Lane wrote:
Lee Hachadoorian<lee.hachadoorian@xxxxxxxxx> writes:
And can I reliably retrieve the original integer by
casting to int (or bigint) if the number of digits in the original
integer is less than 15?
On IEEE-floating-point machines, I'd expect float8 to store integers
up to 2^52 (or maybe it's 2^53) exactly. With other floating-point
formats the limit might be different, but it should still be exact for
reasonable-size integers. This has nothing whatever to do with whether
decimal fractions are reproduced exactly (in general, they aren't, no
matter how many or few digits are involved). So integers are fine,
bigints not so much.
regards, tom lane
Thank you, that clarification is extremely useful. --Lee
--
Lee Hachadoorian
PhD, Earth& Environmental Sciences (Geography)
Research Associate, CUNY Center for Urban Research
http://freecity.commons.gc.cuny.edu
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