Re: ALTER COLUMN ... SET EXPRESSION to alter stored generated column's expression

Hi Amul,

On Wed, Aug 2, 2023 at 4:06 PM Amul Sul <sulamul@gmail.com> wrote:

Hi,

Currently, we have an option to drop the expression of stored generated columns
as:

ALTER [ COLUMN ] column_name DROP EXPRESSION [ IF EXISTS ]

But don't have support to update that expression. The attached patch provides
that as:

ALTER [ COLUMN ] column_name SET EXPRESSION expression

+1 to the idea.

3. The AlteredTableInfo structure has member Relation, So need to pass parameter Relation separately?

static ObjectAddress ATExecColumnExpression(AlteredTableInfo *tab, Relation rel,
     const char *colName, Node *newDefault,
     bool missing_ok, LOCKMODE lockmode);