Re: float8 auto truncation issue in ODBC v. PGSQL

[Hiroshi Inoue <inoue(at)tpf(dot)co(dot)jp>]

postgresql(dot)org(at)tgice(dot)com wrote:
> Not sure if the ODBC list is the best place for this question, but I've 
> encountered some strange behavior and was wondering if anyone had an 
> idea as to what's going on.
>
> I've got a float8 data type in a column.  I have a value '1.0475' 
> inserted into it.  That number cannot of course be perfectly represented 
> as a float8.
>
> When I perform a test like this in MSSQL 7, e.g., and select it using 
> any variety of tools I get this out:
>
>   1.0475000000000001
>
> When I use my own ODBC SQL client to select the same value from my 
> Postgres 8.0 database, I get the same thing:
>
>   1.0475000000000001
>
> *However*, and here's the troubling part, when I select the exact same 
> value using psql (and I have reason to believe the same thing is going 
> on inside pl/pgsql functions), the value that comes out is:
>
>   1.0475
>
> Now, some of you may say, "What's your problem?  That's actually the 
> correct value!"  That's true, it is.  However, I'm confused as to the 
> differences between the result I get *from* PG via my ODBC client and 
> what Postgres shows with it's internal tools.

The odbc driver automatically issues *set extra_float_digits to 2*
 command at the beginning.

regards,
Hiroshi Inoue