subselect.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

		List	   *newargs = NIL;
		ListCell   *l;

		foreach(l, ((BoolExpr *) node)->args)
		{
			Node	   *newarg;

			newarg = process_sublinks_mutator(lfirst(l),
											  (void *) &locTopQual);
			if (or_clause(newarg))
				newargs = list_concat(newargs, ((BoolExpr *) newarg)->args);
			else
				newargs = lappend(newargs, newarg);
		}
		return (Node *) make_orclause(newargs);
	}

	return expression_tree_mutator(node,
								   process_sublinks_mutator,
								   (void *) &locTopQual);
}

/*
 * SS_finalize_plan - do final sublink processing for a completed Plan.
 *
 * This recursively computes the extParam and allParam sets for every Plan
 * node in the given plan tree.  It also attaches any generated InitPlans
 * to the top plan node.
 */
void
SS_finalize_plan(Plan *plan, List *rtable)
{
	Bitmapset  *outer_params,
			   *valid_params,
			   *initExtParam,
			   *initSetParam;
	Cost		initplan_cost;
	int			paramid;
	ListCell   *l;

	/*
	 * First, scan the param list to discover the sets of params that are
	 * available from outer query levels and my own query level. We do this
	 * once to save time in the per-plan recursion steps.
	 */
	outer_params = valid_params = NULL;
	paramid = 0;
	foreach(l, PlannerParamList)
	{
		PlannerParamItem *pitem = (PlannerParamItem *) lfirst(l);

		if (pitem->abslevel < PlannerQueryLevel)
		{
			/* valid outer-level parameter */
			outer_params = bms_add_member(outer_params, paramid);
			valid_params = bms_add_member(valid_params, paramid);
		}
		else if (pitem->abslevel == PlannerQueryLevel &&
				 IsA(pitem->item, Param))
		{
			/* valid local parameter (i.e., a setParam of my child) */
			valid_params = bms_add_member(valid_params, paramid);
		}

		paramid++;
	}

	/*
	 * Now recurse through plan tree.
	 */
	(void) finalize_plan(plan, rtable, outer_params, valid_params);

	bms_free(outer_params);
	bms_free(valid_params);

	/*
	 * Finally, attach any initPlans to the topmost plan node, and add their
	 * extParams to the topmost node's, too.  However, any setParams of the
	 * initPlans should not be present in the topmost node's extParams, only
	 * in its allParams.  (As of PG 8.1, it's possible that some initPlans
	 * have extParams that are setParams of other initPlans, so we have to
	 * take care of this situation explicitly.)
	 *
	 * We also add the total_cost of each initPlan to the startup cost of the
	 * top node.  This is a conservative overestimate, since in fact each
	 * initPlan might be executed later than plan startup, or even not at all.
	 */
	plan->initPlan = PlannerInitPlan;
	PlannerInitPlan = NIL;		/* make sure they're not attached twice */

	initExtParam = initSetParam = NULL;
	initplan_cost = 0;
	foreach(l, plan->initPlan)
	{
		SubPlan    *initplan = (SubPlan *) lfirst(l);
		ListCell   *l2;

		initExtParam = bms_add_members(initExtParam,
									   initplan->plan->extParam);
		foreach(l2, initplan->setParam)
		{
			initSetParam = bms_add_member(initSetParam, lfirst_int(l2));
		}
		initplan_cost += initplan->plan->total_cost;
	}
	/* allParam must include all these params */
	plan->allParam = bms_add_members(plan->allParam, initExtParam);
	plan->allParam = bms_add_members(plan->allParam, initSetParam);
	/* but extParam shouldn't include any setParams */
	initExtParam = bms_del_members(initExtParam, initSetParam);
	/* empty test ensures extParam is exactly NULL if it's empty */
	if (!bms_is_empty(initExtParam))
		plan->extParam = bms_join(plan->extParam, initExtParam);

	plan->startup_cost += initplan_cost;
	plan->total_cost += initplan_cost;
}

/*
 * Recursive processing of all nodes in the plan tree
 *
 * The return value is the computed allParam set for the given Plan node.
 * This is just an internal notational convenience.
 */
static Bitmapset *
finalize_plan(Plan *plan, List *rtable,
			  Bitmapset *outer_params, Bitmapset *valid_params)
{
	finalize_primnode_context context;

	if (plan == NULL)
		return NULL;

	context.paramids = NULL;	/* initialize set to empty */
	context.outer_params = outer_params;

	/*
	 * When we call finalize_primnode, context.paramids sets are automatically
	 * merged together.  But when recursing to self, we have to do it the hard
	 * way.  We want the paramids set to include params in subplans as well as
	 * at this level.
	 */

	/* Find params in targetlist and qual */
	finalize_primnode((Node *) plan->targetlist, &context);
	finalize_primnode((Node *) plan->qual, &context);

	/* Check additional node-type-specific fields */
	switch (nodeTag(plan))
	{
		case T_Result:
			finalize_primnode(((Result *) plan)->resconstantqual,
							  &context);
			break;

		case T_IndexScan:
			finalize_primnode((Node *) ((IndexScan *) plan)->indexqual,
							  &context);

			/*
			 * we need not look at indexqualorig, since it will have the same
			 * param references as indexqual.
			 */
			break;

		case T_BitmapIndexScan:
			finalize_primnode((Node *) ((BitmapIndexScan *) plan)->indexqual,
							  &context);

			/*
			 * we need not look at indexqualorig, since it will have the same
			 * param references as indexqual.
			 */
			break;

		case T_BitmapHeapScan:
			finalize_primnode((Node *) ((BitmapHeapScan *) plan)->bitmapqualorig,
							  &context);
			break;

		case T_TidScan:
			finalize_primnode((Node *) ((TidScan *) plan)->tideval,
							  &context);
			break;

		case T_SubqueryScan:

			/*
			 * In a SubqueryScan, SS_finalize_plan has already been run on the
			 * subplan by the inner invocation of subquery_planner, so there's
			 * no need to do it again.	Instead, just pull out the subplan's
			 * extParams list, which represents the params it needs from my
			 * level and higher levels.
			 */
			context.paramids = bms_add_members(context.paramids,
								 ((SubqueryScan *) plan)->subplan->extParam);
			break;

		case T_FunctionScan:
			{
				RangeTblEntry *rte;

				rte = rt_fetch(((FunctionScan *) plan)->scan.scanrelid,
							   rtable);
				Assert(rte->rtekind == RTE_FUNCTION);
				finalize_primnode(rte->funcexpr, &context);
			}
			break;

		case T_Append:
			{
				ListCell   *l;

				foreach(l, ((Append *) plan)->appendplans)
				{
					context.paramids =
						bms_add_members(context.paramids,
										finalize_plan((Plan *) lfirst(l),
													  rtable,
													  outer_params,
													  valid_params));
				}
			}
			break;

		case T_BitmapAnd:
			{
				ListCell   *l;

				foreach(l, ((BitmapAnd *) plan)->bitmapplans)
				{
					context.paramids =
						bms_add_members(context.paramids,
										finalize_plan((Plan *) lfirst(l),
													  rtable,
													  outer_params,
													  valid_params));
				}
			}
			break;

		case T_BitmapOr:
			{
				ListCell   *l;

				foreach(l, ((BitmapOr *) plan)->bitmapplans)
				{
					context.paramids =
						bms_add_members(context.paramids,
										finalize_plan((Plan *) lfirst(l),
													  rtable,
													  outer_params,
													  valid_params));
				}
			}
			break;

		case T_NestLoop:
			finalize_primnode((Node *) ((Join *) plan)->joinqual,
							  &context);
			break;

		case T_MergeJoin:
			finalize_primnode((Node *) ((Join *) plan)->joinqual,
							  &context);
			finalize_primnode((Node *) ((MergeJoin *) plan)->mergeclauses,
							  &context);
			break;

		case T_HashJoin:
			finalize_primnode((Node *) ((Join *) plan)->joinqual,
							  &context);
			finalize_primnode((Node *) ((HashJoin *) plan)->hashclauses,
							  &context);
			break;

		case T_Limit:
			finalize_primnode(((Limit *) plan)->limitOffset,
							  &context);
			finalize_primnode(((Limit *) plan)->limitCount,
							  &context);
			break;

		case T_Hash:
		case T_Agg:
		case T_SeqScan:
		case T_Material:
		case T_Sort:
		case T_Unique:
		case T_SetOp:
		case T_Group:
			break;

		default:
			elog(ERROR, "unrecognized node type: %d",
				 (int) nodeTag(plan));
	}

	/* Process left and right child plans, if any */
	context.paramids = bms_add_members(context.paramids,
									   finalize_plan(plan->lefttree,
													 rtable,
													 outer_params,
													 valid_params));

	context.paramids = bms_add_members(context.paramids,
									   finalize_plan(plan->righttree,
													 rtable,
													 outer_params,
													 valid_params));

	/* Now we have all the paramids */

	if (!bms_is_subset(context.paramids, valid_params))
		elog(ERROR, "plan should not reference subplan's variable");

	plan->extParam = bms_intersect(context.paramids, outer_params);
	plan->allParam = context.paramids;

	/*
	 * For speed at execution time, make sure extParam/allParam are actually
	 * NULL if they are empty sets.
	 */
	if (bms_is_empty(plan->extParam))
	{
		bms_free(plan->extParam);
		plan->extParam = NULL;
	}
	if (bms_is_empty(plan->allParam))
	{
		bms_free(plan->allParam);
		plan->allParam = NULL;
	}

	return plan->allParam;
}

/*
 * finalize_primnode: add IDs of all PARAM_EXEC params appearing in the given
 * expression tree to the result set.
 */
static bool
finalize_primnode(Node *node, finalize_primnode_context *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, Param))
	{
		if (((Param *) node)->paramkind == PARAM_EXEC)
		{
			int			paramid = (int) ((Param *) node)->paramid;

			context->paramids = bms_add_member(context->paramids, paramid);
		}
		return false;			/* no more to do here */
	}
	if (is_subplan(node))
	{
		SubPlan    *subplan = (SubPlan *) node;

		/* Add outer-level params needed by the subplan to paramids */
		context->paramids = bms_join(context->paramids,
									 bms_intersect(subplan->plan->extParam,
												   context->outer_params));
		/* fall through to recurse into subplan args */
	}
	return expression_tree_walker(node, finalize_primnode,
								  (void *) context);
}

/*
 * SS_make_initplan_from_plan - given a plan tree, make it an InitPlan
 *
 * The plan is expected to return a scalar value of the indicated type.
 * We build an EXPR_SUBLINK SubPlan node and put it into the initplan
 * list for the current query level.  A Param that represents the initplan's
 * output is returned.
 *
 * We assume the plan hasn't been put through SS_finalize_plan.
 */
Param *
SS_make_initplan_from_plan(PlannerInfo *root, Plan *plan,
						   Oid resulttype, int32 resulttypmod)
{
	List	   *saved_initplan = PlannerInitPlan;
	SubPlan    *node;
	Param	   *prm;

	/*
	 * Set up for a new level of subquery.	This is just to keep
	 * SS_finalize_plan from becoming confused.
	 */
	PlannerQueryLevel++;
	PlannerInitPlan = NIL;

	/*
	 * Build extParam/allParam sets for plan nodes.
	 */
	SS_finalize_plan(plan, root->parse->rtable);

	/* Return to outer subquery context */
	PlannerQueryLevel--;
	PlannerInitPlan = saved_initplan;

	/*
	 * Create a SubPlan node and add it to the outer list of InitPlans.
	 */
	node = makeNode(SubPlan);
	node->subLinkType = EXPR_SUBLINK;
	node->plan = plan;
	node->plan_id = PlannerPlanId++;	/* Assign unique ID to this SubPlan */

	node->rtable = root->parse->rtable;

	PlannerInitPlan = lappend(PlannerInitPlan, node);

	/*
	 * The node can't have any inputs (since it's an initplan), so the
	 * parParam and args lists remain empty.
	 */

	/*
	 * Make a Param that will be the subplan's output.
	 */
	prm = generate_new_param(resulttype, resulttypmod);
	node->setParam = list_make1_int(prm->paramid);

	return prm;
}