Re: Timestamp precision and rounding

Stephan Szabo wrote:

>On Thu, 3 Jun 2004, Jeff Boes wrote:
>
>
>
>>(asked last week on .questions, no response)
>>
>>Can anyone explain why this happens?  (under 7.4.1)
>>
>>    select '2004-05-27 09:00:00.500001-04' :: timestamp(0) ;
>>
>>          timestamp
>>    ---------------------
>>     2004-05-27 09:00:01
>>
>>
>>    select '2004-05-27 09:00:00.500000-04' :: timestamp(0) ;
>>
>>          timestamp
>>    ---------------------
>>     2004-05-27 09:00:00
>>
>>
>>That is, why doesn't the second operation result in the same timestamp
>>as the first? Is it a floating-point representation issue, or are the
>>mathematical rules of rounding not being followed correctly (as I
>>understand them, anyway)?
>>
>>
>
>My first guess would be that your system probably implements its default
>rounding as nearest even for .5 results, what does 9:00:01.5 give you?
>
>
2004-05-27 09:00:02, so I guess  that would confirm it.


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