Re: ResultSetMetaData + CachedResultSet bug

[Thomas Hallgren <thomas(at)tada(dot)se>]

Kris Jurka wrote:
> On Thu, 22 Jun 2006, Sergii Sinelnychenko wrote:
>
> >   Today I have found a strange bug in JDBC driver (I used the last 
> > version avilable - 8.2dev-503). The problem is with VARCHAR fields - 
> > driver returns "-1" on "getPrecision()" call. But class 
> > javax.sql.rowset.RowSetMetaDataImpl in its "setPrecision()" method 
> > requires values of 0 and more (javadoc sais "precision the total 
> > number of decimal digits; must be <code>0</code> or more ").
> > I understand that in case of VARCHAR type we cannot speak about real 
> > number of decimal digits - but could just driver return 0 instead of -1?
>
>
> That certainly looks like a reasonable thing to do for text types.  The 
> one case that needs a little more thinking about is a numeric field that 
> has neither precision nor scale supplied.  For this we currently return 
> -1 for both precision and scale.  The maximum precision of a numeric is 
> 1000 digits, so we could divy it up evenly and make an unadorned numeric 
> be returned as numeric(1000,500), but that seems a little too much like 
> just making things up.  Thoughts?
I think the current -1 is reasonable for non numeric types. For the numeric types however, 
the interpretation should be that 0 is unlimited. A numeric should never return -1 and 
should accept setPrecision(colidx, 0) as 'no limit', i.e.

 0 = unlimited
-1 = not applicable

A setPrecision call on types where precision has no meaning should IMO yield an exception.

The rationale is that a) stating that a varchar has zero decimal digits is wrong since it 
doesn't have any notion of decimal digits, and b) a precision of zero for a numeric doesn't 
make sense when interpreted verbatim.

Regards,
Thomas Hallgren