Function ATSimpleRecursion

src/backend/commands/tablecmds.c:7949–7985

* ATSimpleRecursion * * Simple table recursion sufficient for most ALTER TABLE operations. * All direct and indirect children are processed in an unspecified order. * Note that if a child inherits from the original table via multiple * inheritance paths, it will be visited just once. */

 * inheritance paths, it will be visited just once.
 */
static void
ATSimpleRecursion(List **wqueue, Relation rel,
				  AlterTableCmd *cmd, bool recurse, LOCKMODE lockmode,
				  AlterTableUtilityContext *context)
{
	/*
	 * Propagate to children, if desired and if there are (or might be) any
	 * children.
	 */
	if (recurse && rel->rd_rel->relhassubclass)
	{
		Oid			relid = RelationGetRelid(rel);
		ListCell   *child;
		List	   *children;

		children = find_all_inheritors(relid, lockmode, NULL);

		/*
		 * find_all_inheritors does the recursive search of the inheritance
		 * hierarchy, so all we have to do is process all of the relids in the
		 * list that it returns.
		 */
		foreach(child, children)
		{
			Oid			childrelid = lfirst_oid(child);
			Relation	childrel;

			if (childrelid == relid)
				continue;
			/* find_all_inheritors already got lock */
			childrel = relation_open(childrelid, NoLock);
			CheckTableNotInUse(childrel, "ALTER TABLE");
			ATPrepCmd(wqueue, childrel, cmd, false, true, lockmode, context);
			relation_close(childrel, NoLock);
		}
	}
}

/*
 * Obtain list of partitions of the given table, locking them all at the given