Re: ResultSetMetaData + CachedResultSet bug

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