Re: About PostgreSQL's limit on arithmetic operations

On Wednesday 29 Sep 2004 2:25 pm, Devrim GUNDUZ wrote:
> > template1=# SELECT 512*18014398509481984::numeric(20) AS result;
> > result
> > ---------------------
> > 9223372036854775808
> > (1 row)
>
> Ok, I got the same result in 7.4.5... But... Why do we have to cast it
> into numeric? The results from other databases shows that they can perform
> it without casting...

Probably because the normal integer is 4 bytes long and bigint is 8 bytes
long. The value above is exactly 2^63 at which a 8 bytes long signed bigint
should flip sign/overflow. I am still puzzled with correct value and negative
sign..

For arbitrary precision integer, you have to use numeric. It is not same as
oracle.

Furthermore if your number fit in range, then numbers like precision(4,0) in
oracle to smallint in postgresql would buy you huge speed
improvement(compared to postgresql numeric I mean)

Please correct me if I am wrong..

Shridhar