Re: Arbitrary precision arithmatic with pgsql

On Aug 31, 2004, at 8:55 PM, Rajesh Kumar Mallah wrote:

> The docs says that numeric type supports numbers upto
> any precision

<snip />

> However
>
> tradein_clients=# SELECT cast(2^100 as numeric);

<snip />

> 1. Does the specs not require pgsql to print a warning or info ,
> will it not be considered silient truncation of data.

AFAICS, the issue here is not the cast per se, but rather the power
operation (2^100), which expects a double precision argument. This
operation happens before the cast.

> 2. Is there any way to do such calculation using pgsql, i understand
> bc is a better tool for it.

What you need is a power operation for numeric, which I think you'd
have to write yourself, possibly leveraging one of the procedural
languages (perhaps pl/perl) to access such an operation (as you
yourself mentioned). I'm sure you could find an algorithm to port to
PL/pgsql as well.

Hope this helps.

Michael Glaesemann
grzm myrealbox com