setrefs.c

来自「postgresql8.3.4源码,开源数据库」· C语言 代码 · 共 1,627 行 · 第 1/4 页

				splan->resconstantqual =
					fix_scan_expr(glob, splan->resconstantqual, rtoffset);
			}
			break;
		case T_Append:
			{
				Append	   *splan = (Append *) plan;

				/*
				 * Append, like Sort et al, doesn't actually evaluate its
				 * targetlist or check quals.
				 */
				set_dummy_tlist_references(plan, rtoffset);
				Assert(splan->plan.qual == NIL);
				foreach(l, splan->appendplans)
				{
					lfirst(l) = set_plan_refs(glob,
											  (Plan *) lfirst(l),
											  rtoffset);
				}
			}
			break;
		case T_BitmapAnd:
			{
				BitmapAnd  *splan = (BitmapAnd *) plan;

				/* BitmapAnd works like Append, but has no tlist */
				Assert(splan->plan.targetlist == NIL);
				Assert(splan->plan.qual == NIL);
				foreach(l, splan->bitmapplans)
				{
					lfirst(l) = set_plan_refs(glob,
											  (Plan *) lfirst(l),
											  rtoffset);
				}
			}
			break;
		case T_BitmapOr:
			{
				BitmapOr   *splan = (BitmapOr *) plan;

				/* BitmapOr works like Append, but has no tlist */
				Assert(splan->plan.targetlist == NIL);
				Assert(splan->plan.qual == NIL);
				foreach(l, splan->bitmapplans)
				{
					lfirst(l) = set_plan_refs(glob,
											  (Plan *) lfirst(l),
											  rtoffset);
				}
			}
			break;
		default:
			elog(ERROR, "unrecognized node type: %d",
				 (int) nodeTag(plan));
			break;
	}

	/*
	 * Now recurse into child plans, if any
	 *
	 * NOTE: it is essential that we recurse into child plans AFTER we set
	 * subplan references in this plan's tlist and quals.  If we did the
	 * reference-adjustments bottom-up, then we would fail to match this
	 * plan's var nodes against the already-modified nodes of the children.
	 */
	plan->lefttree = set_plan_refs(glob, plan->lefttree, rtoffset);
	plan->righttree = set_plan_refs(glob, plan->righttree, rtoffset);

	return plan;
}

/*
 * set_subqueryscan_references
 *		Do set_plan_references processing on a SubqueryScan
 *
 * We try to strip out the SubqueryScan entirely; if we can't, we have
 * to do the normal processing on it.
 */
static Plan *
set_subqueryscan_references(PlannerGlobal *glob,
							SubqueryScan *plan,
							int rtoffset)
{
	Plan	   *result;

	/* First, recursively process the subplan */
	plan->subplan = set_plan_references(glob, plan->subplan, plan->subrtable);

	/* subrtable is no longer needed in the plan tree */
	plan->subrtable = NIL;

	if (trivial_subqueryscan(plan))
	{
		/*
		 * We can omit the SubqueryScan node and just pull up the subplan.
		 */
		ListCell   *lp,
				   *lc;

		result = plan->subplan;

		/* We have to be sure we don't lose any initplans */
		result->initPlan = list_concat(plan->scan.plan.initPlan,
									   result->initPlan);

		/*
		 * We also have to transfer the SubqueryScan's result-column names
		 * into the subplan, else columns sent to client will be improperly
		 * labeled if this is the topmost plan level.  Copy the "source
		 * column" information too.
		 */
		forboth(lp, plan->scan.plan.targetlist, lc, result->targetlist)
		{
			TargetEntry *ptle = (TargetEntry *) lfirst(lp);
			TargetEntry *ctle = (TargetEntry *) lfirst(lc);

			ctle->resname = ptle->resname;
			ctle->resorigtbl = ptle->resorigtbl;
			ctle->resorigcol = ptle->resorigcol;
		}
	}
	else
	{
		/*
		 * Keep the SubqueryScan node.	We have to do the processing that
		 * set_plan_references would otherwise have done on it.  Notice we do
		 * not do set_upper_references() here, because a SubqueryScan will
		 * always have been created with correct references to its subplan's
		 * outputs to begin with.
		 */
		plan->scan.scanrelid += rtoffset;
		plan->scan.plan.targetlist =
			fix_scan_list(glob, plan->scan.plan.targetlist, rtoffset);
		plan->scan.plan.qual =
			fix_scan_list(glob, plan->scan.plan.qual, rtoffset);

		result = (Plan *) plan;
	}

	return result;
}

/*
 * trivial_subqueryscan
 *		Detect whether a SubqueryScan can be deleted from the plan tree.
 *
 * We can delete it if it has no qual to check and the targetlist just
 * regurgitates the output of the child plan.
 */
static bool
trivial_subqueryscan(SubqueryScan *plan)
{
	int			attrno;
	ListCell   *lp,
			   *lc;

	if (plan->scan.plan.qual != NIL)
		return false;

	if (list_length(plan->scan.plan.targetlist) !=
		list_length(plan->subplan->targetlist))
		return false;			/* tlists not same length */

	attrno = 1;
	forboth(lp, plan->scan.plan.targetlist, lc, plan->subplan->targetlist)
	{
		TargetEntry *ptle = (TargetEntry *) lfirst(lp);
		TargetEntry *ctle = (TargetEntry *) lfirst(lc);

		if (ptle->resjunk != ctle->resjunk)
			return false;		/* tlist doesn't match junk status */

		/*
		 * We accept either a Var referencing the corresponding element of the
		 * subplan tlist, or a Const equaling the subplan element. See
		 * generate_setop_tlist() for motivation.
		 */
		if (ptle->expr && IsA(ptle->expr, Var))
		{
			Var		   *var = (Var *) ptle->expr;

			Assert(var->varno == plan->scan.scanrelid);
			Assert(var->varlevelsup == 0);
			if (var->varattno != attrno)
				return false;	/* out of order */
		}
		else if (ptle->expr && IsA(ptle->expr, Const))
		{
			if (!equal(ptle->expr, ctle->expr))
				return false;
		}
		else
			return false;

		attrno++;
	}

	return true;
}

/*
 * copyVar
 *		Copy a Var node.
 *
 * fix_scan_expr and friends do this enough times that it's worth having
 * a bespoke routine instead of using the generic copyObject() function.
 */
static inline Var *
copyVar(Var *var)
{
	Var		   *newvar = (Var *) palloc(sizeof(Var));

	*newvar = *var;
	return newvar;
}

/*
 * fix_scan_expr
 *		Do set_plan_references processing on a scan-level expression
 *
 * This consists of incrementing all Vars' varnos by rtoffset,
 * looking up operator opcode info for OpExpr and related nodes,
 * and adding OIDs from regclass Const nodes into glob->relationOids.
 */
static Node *
fix_scan_expr(PlannerGlobal *glob, Node *node, int rtoffset)
{
	fix_scan_expr_context context;

	context.glob = glob;
	context.rtoffset = rtoffset;

	if (rtoffset != 0)
	{
		return fix_scan_expr_mutator(node, &context);
	}
	else
	{
		/*
		 * If rtoffset == 0, we don't need to change any Vars, which makes
		 * it OK to just scribble on the input node tree instead of copying
		 * (since the only change, filling in any unset opfuncid fields,
		 * is harmless).  This saves just enough cycles to be noticeable on
		 * trivial queries.
		 */
		(void) fix_scan_expr_walker(node, &context);
		return node;
	}
}

static Node *
fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context)
{
	if (node == NULL)
		return NULL;
	if (IsA(node, Var))
	{
		Var		   *var = copyVar((Var *) node);

		Assert(var->varlevelsup == 0);

		/*
		 * We should not see any Vars marked INNER, but in a nestloop inner
		 * scan there could be OUTER Vars.	Leave them alone.
		 */
		Assert(var->varno != INNER);
		if (var->varno > 0 && var->varno != OUTER)
			var->varno += context->rtoffset;
		if (var->varnoold > 0)
			var->varnoold += context->rtoffset;
		return (Node *) var;
	}
	if (IsA(node, CurrentOfExpr))
	{
		CurrentOfExpr *cexpr = (CurrentOfExpr *) copyObject(node);

		Assert(cexpr->cvarno != INNER);
		Assert(cexpr->cvarno != OUTER);
		cexpr->cvarno += context->rtoffset;
		return (Node *) cexpr;
	}

	/*
	 * Since we update opcode info in-place, this part could possibly scribble
	 * on the planner's input data structures, but it's OK.
	 */
	if (IsA(node, OpExpr))
		set_opfuncid((OpExpr *) node);
	else if (IsA(node, DistinctExpr))
		set_opfuncid((OpExpr *) node);	/* rely on struct equivalence */
	else if (IsA(node, NullIfExpr))
		set_opfuncid((OpExpr *) node);	/* rely on struct equivalence */
	else if (IsA(node, ScalarArrayOpExpr))
		set_sa_opfuncid((ScalarArrayOpExpr *) node);
	else if (IsA(node, Const))
	{
		Const	   *con = (Const *) node;

		/* Check for regclass reference */
		if (ISREGCLASSCONST(con))
			context->glob->relationOids =
				lappend_oid(context->glob->relationOids,
							DatumGetObjectId(con->constvalue));
		/* Fall through to let expression_tree_mutator copy it */
	}
	return expression_tree_mutator(node, fix_scan_expr_mutator,
								   (void *) context);
}

static bool
fix_scan_expr_walker(Node *node, fix_scan_expr_context *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, OpExpr))
		set_opfuncid((OpExpr *) node);
	else if (IsA(node, DistinctExpr))
		set_opfuncid((OpExpr *) node);	/* rely on struct equivalence */
	else if (IsA(node, NullIfExpr))
		set_opfuncid((OpExpr *) node);	/* rely on struct equivalence */
	else if (IsA(node, ScalarArrayOpExpr))
		set_sa_opfuncid((ScalarArrayOpExpr *) node);
	else if (IsA(node, Const))
	{
		Const	   *con = (Const *) node;

		/* Check for regclass reference */
		if (ISREGCLASSCONST(con))
			context->glob->relationOids =
				lappend_oid(context->glob->relationOids,
							DatumGetObjectId(con->constvalue));
		return false;
	}
	return expression_tree_walker(node, fix_scan_expr_walker,
								  (void *) context);
}

/*
 * set_join_references
 *	  Modify the target list and quals of a join node to reference its
 *	  subplans, by setting the varnos to OUTER or INNER and setting attno
 *	  values to the result domain number of either the corresponding outer
 *	  or inner join tuple item.  Also perform opcode lookup for these
 *	  expressions. and add regclass OIDs to glob->relationOids.
 *
 * In the case of a nestloop with inner indexscan, we will also need to
 * apply the same transformation to any outer vars appearing in the
 * quals of the child indexscan.  set_inner_join_references does that.
 */
static void
set_join_references(PlannerGlobal *glob, Join *join, int rtoffset)
{
	Plan	   *outer_plan = join->plan.lefttree;
	Plan	   *inner_plan = join->plan.righttree;
	indexed_tlist *outer_itlist;
	indexed_tlist *inner_itlist;

	outer_itlist = build_tlist_index(outer_plan->targetlist);
	inner_itlist = build_tlist_index(inner_plan->targetlist);

	/* All join plans have tlist, qual, and joinqual */
	join->plan.targetlist = fix_join_expr(glob,
										  join->plan.targetlist,
										  outer_itlist,
										  inner_itlist,
										  (Index) 0,
										  rtoffset);
	join->plan.qual = fix_join_expr(glob,
									join->plan.qual,
									outer_itlist,
									inner_itlist,
									(Index) 0,
									rtoffset);
	join->joinqual = fix_join_expr(glob,
								   join->joinqual,
								   outer_itlist,
								   inner_itlist,
								   (Index) 0,
								   rtoffset);

	/* Now do join-type-specific stuff */
	if (IsA(join, NestLoop))
	{
		/* This processing is split out to handle possible recursion */
		set_inner_join_references(glob, inner_plan, outer_itlist);
	}
	else if (IsA(join, MergeJoin))
	{
		MergeJoin  *mj = (MergeJoin *) join;

		mj->mergeclauses = fix_join_expr(glob,
										 mj->mergeclauses,
										 outer_itlist,
										 inner_itlist,
										 (Index) 0,
										 rtoffset);
	}
	else if (IsA(join, HashJoin))
	{
		HashJoin   *hj = (HashJoin *) join;

		hj->hashclauses = fix_join_expr(glob,
										hj->hashclauses,
										outer_itlist,
										inner_itlist,
										(Index) 0,