Re: Roadmap for FE/BE protocol redesign

Tom Lane wrote:
> "Dave Page" <dpage@vale-housing.co.uk> writes:
> 
>>What about the addition of pg_attribute.attrelid &
>>pg_attribute.attname/attnum in RowDesription messages to identify the
>>underlying attribute (where appropriate)?
> 
> Well, we can talk about it, but I still think that any frontend that
> relies on such information is broken by design.  (And if that means the
> JDBC spec is broken, then the JDBC spec is broken.)
> 
> Just to start with, if I do "SELECT * FROM view", am I going to see the
> info associated with the view column, or with the hypothetical
> underlying table column?  (Actually, didn't I already make a list of a
> bunch of ways in which this concept is underspecified?  AFAIR, you
> didn't suggest answers to any of those questions ... but we need answers
> to all of them if we are going to implement the feature.)

The problem Dave is suggesting this as a first attempt at a solution for 
is that with ODBC, a frontend (i.e. OpenOffice) asks the ODBC driver 
which columns are NULLable, etc.  And the ODBC driver is getting the 
info wrong, then passing back the incorrect info.

So, when a person goes to insert a row into a table with a 
SERIAL/SEQUENCE based column, OpenOffice has been told the column isn't 
NULLable and forces the user to enter a value.  Voila, it doesn't work 
with sequences.  :(

It's likely possible to add to the ODBC driver some way of getting the 
info right, but Dave is also looking for a way of making this easier 
into the future for similar problems.  i.e. Let the database explicitly 
have info about what each column can do.

That's my understanding of it anyway.

:-)

Regards and best wishes,

Justin Clift


>             regards, tom lane


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