prepunion.c

PostgreSQL7.4.6 for Linux

		inhRTIs = makeListi1(rti);		/* include original RTE in result */

	foreach(l, inhOIDs)
	{
		Oid			childOID = lfirsto(l);
		RangeTblEntry *childrte;
		Index		childRTindex;

		/* parent will be in the list too; skip it if not dup requested */
		if (childOID == parentOID && !dup_parent)
			continue;

		/*
		 * Build an RTE for the child, and attach to query's rangetable
		 * list. We copy most fields of the parent's RTE, but replace
		 * relation real name and OID.	Note that inh will be false at
		 * this point.
		 */
		childrte = copyObject(rte);
		childrte->relid = childOID;
		parse->rtable = lappend(parse->rtable, childrte);
		childRTindex = length(parse->rtable);

		inhRTIs = lappendi(inhRTIs, childRTindex);
	}

	return inhRTIs;
}

/*
 * adjust_inherited_attrs
 *	  Copy the specified query or expression and translate Vars referring
 *	  to old_rt_index to refer to new_rt_index.
 *
 * We also adjust varattno to match the new table by column name, rather
 * than column number.	This hack makes it possible for child tables to have
 * different column positions for the "same" attribute as a parent, which
 * helps ALTER TABLE ADD COLUMN.  Unfortunately this isn't nearly enough to
 * make it work transparently; there are other places where things fall down
 * if children and parents don't have the same column numbers for inherited
 * attributes.	It'd be better to rip this code out and fix ALTER TABLE...
 */
Node *
adjust_inherited_attrs(Node *node,
					   Index old_rt_index, Oid old_relid,
					   Index new_rt_index, Oid new_relid)
{
	adjust_inherited_attrs_context context;

	/* Handle simple case simply... */
	if (old_rt_index == new_rt_index)
	{
		Assert(old_relid == new_relid);
		return copyObject(node);
	}

	context.old_rt_index = old_rt_index;
	context.new_rt_index = new_rt_index;
	context.old_relid = old_relid;
	context.new_relid = new_relid;

	/*
	 * Must be prepared to start with a Query or a bare expression tree.
	 */
	if (node && IsA(node, Query))
	{
		Query	   *newnode;

		newnode = query_tree_mutator((Query *) node,
									 adjust_inherited_attrs_mutator,
									 (void *) &context,
									 QTW_IGNORE_RT_SUBQUERIES);
		if (newnode->resultRelation == old_rt_index)
		{
			newnode->resultRelation = new_rt_index;
			/* Fix tlist resnos too, if it's inherited UPDATE */
			if (newnode->commandType == CMD_UPDATE)
				newnode->targetList =
					adjust_inherited_tlist(newnode->targetList,
										   old_relid,
										   new_relid);
		}
		return (Node *) newnode;
	}
	else
		return adjust_inherited_attrs_mutator(node, &context);
}

static Node *
adjust_inherited_attrs_mutator(Node *node,
							   adjust_inherited_attrs_context *context)
{
	if (node == NULL)
		return NULL;
	if (IsA(node, Var))
	{
		Var		   *var = (Var *) copyObject(node);

		if (var->varlevelsup == 0 &&
			var->varno == context->old_rt_index)
		{
			var->varno = context->new_rt_index;
			var->varnoold = context->new_rt_index;
			if (var->varattno > 0)
			{
				char	   *attname;

				attname = get_relid_attribute_name(context->old_relid,
												   var->varattno);
				var->varattno = get_attnum(context->new_relid, attname);
				if (var->varattno == InvalidAttrNumber)
					elog(ERROR, "attribute \"%s\" of relation \"%s\" does not exist",
						 attname, get_rel_name(context->new_relid));
				var->varoattno = var->varattno;
				pfree(attname);
			}
		}
		return (Node *) var;
	}
	if (IsA(node, RangeTblRef))
	{
		RangeTblRef *rtr = (RangeTblRef *) copyObject(node);

		if (rtr->rtindex == context->old_rt_index)
			rtr->rtindex = context->new_rt_index;
		return (Node *) rtr;
	}
	if (IsA(node, JoinExpr))
	{
		/* Copy the JoinExpr node with correct mutation of subnodes */
		JoinExpr   *j;

		j = (JoinExpr *) expression_tree_mutator(node,
										  adjust_inherited_attrs_mutator,
												 (void *) context);
		/* now fix JoinExpr's rtindex */
		if (j->rtindex == context->old_rt_index)
			j->rtindex = context->new_rt_index;
		return (Node *) j;
	}
	if (IsA(node, InClauseInfo))
	{
		/* Copy the InClauseInfo node with correct mutation of subnodes */
		InClauseInfo *ininfo;

		ininfo = (InClauseInfo *) expression_tree_mutator(node,
										  adjust_inherited_attrs_mutator,
													   (void *) context);
		/* now fix InClauseInfo's relid sets */
		ininfo->lefthand = adjust_relid_set(ininfo->lefthand,
											context->old_rt_index,
											context->new_rt_index);
		ininfo->righthand = adjust_relid_set(ininfo->righthand,
											 context->old_rt_index,
											 context->new_rt_index);
		return (Node *) ininfo;
	}

	/*
	 * We have to process RestrictInfo nodes specially.
	 */
	if (IsA(node, RestrictInfo))
	{
		RestrictInfo *oldinfo = (RestrictInfo *) node;
		RestrictInfo *newinfo = makeNode(RestrictInfo);

		/* Copy all flat-copiable fields */
		memcpy(newinfo, oldinfo, sizeof(RestrictInfo));

		/* Recursively fix the clause itself */
		newinfo->clause = (Expr *)
			adjust_inherited_attrs_mutator((Node *) oldinfo->clause, context);

		/*
		 * We do NOT want to copy the original subclauseindices list,
		 * since the new rel will have different indices.  The list will
		 * be rebuilt when needed during later planning.
		 */
		newinfo->subclauseindices = NIL;

		/*
		 * Adjust left/right relid sets too.
		 */
		newinfo->left_relids = adjust_relid_set(oldinfo->left_relids,
												context->old_rt_index,
												context->new_rt_index);
		newinfo->right_relids = adjust_relid_set(oldinfo->right_relids,
												 context->old_rt_index,
												 context->new_rt_index);

		newinfo->eval_cost.startup = -1;		/* reset these too */
		newinfo->this_selec = -1;
		newinfo->left_pathkey = NIL;	/* and these */
		newinfo->right_pathkey = NIL;
		newinfo->left_mergescansel = -1;
		newinfo->right_mergescansel = -1;
		newinfo->left_bucketsize = -1;
		newinfo->right_bucketsize = -1;

		return (Node *) newinfo;
	}

	/*
	 * NOTE: we do not need to recurse into sublinks, because they should
	 * already have been converted to subplans before we see them.
	 */
	Assert(!IsA(node, SubLink));
	Assert(!IsA(node, Query));

	/*
	 * BUT: although we don't need to recurse into subplans, we do need to
	 * make sure that they are copied, not just referenced as
	 * expression_tree_mutator will do by default.	Otherwise we'll have
	 * the same subplan node referenced from each arm of the inheritance
	 * APPEND plan, which will cause trouble in the executor.  This is a
	 * kluge that should go away when we redesign querytrees.
	 */
	if (is_subplan(node))
	{
		SubPlan    *subplan;

		/* Copy the node and process subplan args */
		node = expression_tree_mutator(node, adjust_inherited_attrs_mutator,
									   (void *) context);
		/* Make sure we have separate copies of subplan and its rtable */
		subplan = (SubPlan *) node;
		subplan->plan = copyObject(subplan->plan);
		subplan->rtable = copyObject(subplan->rtable);
		return node;
	}

	return expression_tree_mutator(node, adjust_inherited_attrs_mutator,
								   (void *) context);
}

/*
 * Substitute newrelid for oldrelid in a Relid set
 */
static Relids
adjust_relid_set(Relids relids, Index oldrelid, Index newrelid)
{
	if (bms_is_member(oldrelid, relids))
	{
		/* Ensure we have a modifiable copy */
		relids = bms_copy(relids);
		/* Remove old, add new */
		relids = bms_del_member(relids, oldrelid);
		relids = bms_add_member(relids, newrelid);
	}
	return relids;
}

/*
 * Adjust the targetlist entries of an inherited UPDATE operation
 *
 * The expressions have already been fixed, but we have to make sure that
 * the target resnos match the child table (they may not, in the case of
 * a column that was added after-the-fact by ALTER TABLE).	In some cases
 * this can force us to re-order the tlist to preserve resno ordering.
 * (We do all this work in special cases so that preptlist.c is fast for
 * the typical case.)
 *
 * The given tlist has already been through expression_tree_mutator;
 * therefore the TargetEntry nodes are fresh copies that it's okay to
 * scribble on.  But the Resdom nodes have not been copied; make new ones
 * if we need to change them!
 *
 * Note that this is not needed for INSERT because INSERT isn't inheritable.
 */
static List *
adjust_inherited_tlist(List *tlist, Oid old_relid, Oid new_relid)
{
	bool		changed_it = false;
	List	   *tl;
	List	   *new_tlist;
	bool		more;
	int			attrno;

	/* Scan tlist and update resnos to match attnums of new_relid */
	foreach(tl, tlist)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(tl);
		Resdom	   *resdom = tle->resdom;
		char	   *attname;

		if (resdom->resjunk)
			continue;			/* ignore junk items */

		attname = get_relid_attribute_name(old_relid, resdom->resno);
		attrno = get_attnum(new_relid, attname);
		if (attrno == InvalidAttrNumber)
			elog(ERROR, "attribute \"%s\" of relation \"%s\" does not exist",
				 attname, get_rel_name(new_relid));
		if (resdom->resno != attrno)
		{
			resdom = (Resdom *) copyObject((Node *) resdom);
			resdom->resno = attrno;
			resdom->resname = attname;
			tle->resdom = resdom;
			changed_it = true;
		}
		else
			pfree(attname);
	}

	/*
	 * If we changed anything, re-sort the tlist by resno, and make sure
	 * resjunk entries have resnos above the last real resno.  The sort
	 * algorithm is a bit stupid, but for such a seldom-taken path, small
	 * is probably better than fast.
	 */
	if (!changed_it)
		return tlist;

	new_tlist = NIL;
	more = true;
	for (attrno = 1; more; attrno++)
	{
		more = false;
		foreach(tl, tlist)
		{
			TargetEntry *tle = (TargetEntry *) lfirst(tl);
			Resdom	   *resdom = tle->resdom;

			if (resdom->resjunk)
				continue;		/* ignore junk items */

			if (resdom->resno == attrno)
				new_tlist = lappend(new_tlist, tle);
			else if (resdom->resno > attrno)
				more = true;
		}
	}

	foreach(tl, tlist)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(tl);
		Resdom	   *resdom = tle->resdom;

		if (!resdom->resjunk)
			continue;			/* here, ignore non-junk items */

		if (resdom->resno != attrno)
		{
			resdom = (Resdom *) copyObject((Node *) resdom);
			resdom->resno = attrno;
			tle->resdom = resdom;
		}
		new_tlist = lappend(new_tlist, tle);
		attrno++;
	}

	return new_tlist;
}