Function ATExecDropInherit

src/backend/commands/tablecmds.c:17438–17480

* ALTER TABLE NO INHERIT * * Return value is the address of the relation that is no longer parent. */

 * Return value is the address of the relation that is no longer parent.
 */
static ObjectAddress
ATExecDropInherit(Relation rel, RangeVar *parent, LOCKMODE lockmode)
{
	ObjectAddress address;
	Relation	parent_rel;

	if (rel->rd_rel->relispartition)
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("cannot change inheritance of a partition")));

	/*
	 * AccessShareLock on the parent is probably enough, seeing that DROP
	 * TABLE doesn't lock parent tables at all.  We need some lock since we'll
	 * be inspecting the parent's schema.
	 */
	parent_rel = table_openrv(parent, AccessShareLock);

	/*
	 * We don't bother to check ownership of the parent table --- ownership of
	 * the child is presumed enough rights.
	 */

	/* Off to RemoveInheritance() where most of the work happens */
	RemoveInheritance(rel, parent_rel, false);

	ObjectAddressSet(address, RelationRelationId,
					 RelationGetRelid(parent_rel));

	/* keep our lock on the parent relation until commit */
	table_close(parent_rel, NoLock);

	/* MPP-6929: metadata tracking */
	if ((Gp_role == GP_ROLE_DISPATCH)
		&& MetaTrackValidKindNsp(rel->rd_rel))
		MetaTrackUpdObject(RelationRelationId,
						   RelationGetRelid(rel),
						   GetUserId(),
						   "ALTER", "NO INHERIT"
		);

	return address;
}

/*
 * MarkInheritDetached