Re: Anomaly with SUM().

Tom Lane wrote:

>Anthony Best <abest(at)digitalflex(dot)net> writes:
>
>
>>I've noticed that the SUM() seems to overflow under some situations.
>>The only difference is the order that the data is retrived from the
>>database.
>>
>>
>
>
>
>>accounting=# select sum(amount) from transactions, chart WHERE
>>account=chart.id;
>> sum
>>---------------------
>>5.6843418860808e-14
>>(1 row)
>>
>>
>
>
>
>>accounting=# select sum(amount) from transactions, chart WHERE
>>account=chart.id AND amount=amount;
>>sum
>>-----
>> 0
>>(1 row)
>>
>>
>
>That's not an overflow, it's merely roundoff error. If this surprises
>you, possibly you should be using type NUMERIC instead of float.
>
> regards, tom lane
>
>
Oh, thats right. 'overflow' was the wrong word. I was thinking numeric
was used internally for 'double precision' for some reason.

thank you.
Anthony.