Re: Disallow USING clause when altering type of generated column

On Thu, 22 Aug 2024 09:10:52 +0200
Peter Eisentraut <peter(at)eisentraut(dot)org> wrote:

> On 22.08.24 08:15, Yugo Nagata wrote:
> > On Thu, 22 Aug 2024 11:38:49 +0800
> > jian he <jian(dot)universality(at)gmail(dot)com> wrote:
> >
> >> On Wed, Aug 21, 2024 at 4:57 PM Peter Eisentraut <peter(at)eisentraut(dot)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(at)sraoss(dot)co(dot)jp>