Re: PreparedStatement rounds doubles to scale 14 during update

Heikki,

Thank you for your reply.

What are base-10 datatypes? Are they numeric types? I cannot find them
in the backend documentation.

Is there a mapping of Java types to backend types documented somewhere?

Thanks a lot
Peter

On 9/5/07, Heikki Linnakangas <heikki(at)enterprisedb(dot)com> wrote:
> Peter Kovacs wrote:
> > Hi,
> >
> > I have the following problem with postgresql-8.1-407.jdbc3.jar used
> > against a 8.1 version backend.
> >
> > A table "chemterms_cols_test" has a column "logp" defined as:
> >
> > logp numeric(30,17)
> >
> > The double value 6.118992224252588 gets rounded to 6.11899222425259000
> > during updates with PreparedStatements using place-holder. (There is
> > no rounding with Statement and the value specified in the SQL
> > literally.) Is this the expected behaviour?
>
> The problem is in the conversion from double to numeric in the server.
> The server-side float8 data type doesn't have enough precision for that
> many decimal places. Because converting between numeric and
> floating-point data types almost always leads to rounding errors at some
> point, I would strongly recommend sticking to base-10 data types
> everywhere if you care about the precision.
>
> If you use BigDecimal instead of double in your java-program, it works fine.
>
> --
> Heikki Linnakangas
> EnterpriseDB http://www.enterprisedb.com
>