Re: Disallow USING clause when altering type of generated column

On Thu, 22 Aug 2024 09:10:52 +0200
Peter Eisentraut <peter@eisentraut.org> wrote:

> On 22.08.24 08:15, Yugo Nagata wrote:
> > On Thu, 22 Aug 2024 11:38:49 +0800
> > jian he <jian.universality@gmail.com> wrote:
> > 
> >> On Wed, Aug 21, 2024 at 4:57 PM Peter Eisentraut <peter@eisentraut.org> wrote:
> >>>
> >>
> >> + /*
> >> + * Cannot specify USING when altering type of a generated column, because
> >> + * that would violate the generation expression.
> >> + */
> >> + if (attTup->attgenerated && def->cooked_default)
> >> + ereport(ERROR,
> >> + (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
> >> + errmsg("cannot specify USING when altering type of generated column"),
> >> + errdetail("Column \"%s\" is a generated column.", colName)));
> >> +
> >>
> >> errcode should be ERRCODE_FEATURE_NOT_SUPPORTED?
> > 
> > 
> > Although ERRCODE_INVALID_TABLE_DEFINITION is used for en error on  changing
> > type of inherited column, I guess that is because it prevents from breaking
> > consistency between inherited and inheriting tables as a result of the command.
> > In this sense, maybe, ERRCODE_INVALID_COLUMN_DEFINITION is proper here, because
> > this check is to prevent inconsistency between columns in a tuple.
> 
> Yes, that was my thinking.  I think of ERRCODE_FEATURE_NOT_SUPPORTED as 
> "we could add it in the future", but that does not seem to apply here.

+				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				 errmsg("cannot specify USING when altering type of generated column"),
+				 errdetail("Column \"%s\" is a generated column.", colName)));

Do you thnik ERRCODE_INVALID_TABLE_DEFINITION is more proper than 
ERRCODE_INVALID_COLUMN_DEFINITION in this case?

Regards,
Yugo Nagata

-- 
Yugo NAGATA <nagata@sraoss.co.jp>