Re: Roadmap for FE/BE protocol redesign

Hiroshi Inoue wrote:
> Tom Lane wrote:
> >
> > Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> writes:
> > > What the driver has suffered from is to get the
> > > fields' info of a query result or the parameters'
> > > info of a statement. The info is needed even before
> > > the execution of the statement(i.e it's only prepared).
> >
> > Hm. Are you saying that you would like PREPARE to send back a
> > RowDescription ('T') message?
>
> I'm not sure if PREPARE should return the info directly.
> Maybe it should be returned only when it is requested.
>
> > Or is there more to it than that?
>
> More detailed field info is needed anyway.
> For example the RowDescription contains neither
> the base column name, the table name nor the
> schema name currently and so the current odbc
> driver couldn't return the info correctly.

But it only needs that info to do system catalog lookups for type, length etc.
Imho the target should be to not need catalog lookups, but get all needed info
from the 'T' message, no?

> The ODBC function SQLDescribeCol or SQLColAttribute
> requires various kind of fields' info.

RETCODE SQL_API SQLDescribeCol(
HSTMT hstmt,
UWORD icol,
UCHAR FAR *szColName,
SWORD cbColNameMax,
SWORD FAR *pcbColName,
SWORD FAR *pfSqlType,
UDWORD FAR *pcbColDef,
SWORD FAR *pibScale,
SWORD FAR *pfNullable);

So you see it does not need tablename or schema.

>
> It's almost impossible to get parameters' info
> currently. The ODBC function SQLDescribeParam
> isn't implemented yet....

Would be same as above, the 'T' message should describe input
and output columns.

Andreas