setrefs.c

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * setrefs.c
 *	  Routines to change varno/attno entries to contain references
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /usr/local/cvsroot/pgsql/src/backend/optimizer/plan/setrefs.c,v 1.50.2.1 1999/08/02 06:27:03 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */
#include <sys/types.h>

#include "postgres.h"



#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/planmain.h"
#include "optimizer/tlist.h"
#include "optimizer/var.h"

static void set_join_tlist_references(Join *join);
static void set_nonamescan_tlist_references(SeqScan *nonamescan);
static void set_noname_tlist_references(Noname *noname);
static Node *replace_clause_joinvar_refs(Node *clause,
							List *outer_tlist,
							List *inner_tlist);
static Var *replace_joinvar_refs(Var *var,
					 List *outer_tlist,
					 List *inner_tlist);
static List *tlist_noname_references(Oid nonameid, List *tlist);
static bool OperandIsInner(Node *opnd, int inner_relid);
static List *pull_agg_clause(Node *clause);
static void set_result_tlist_references(Result *resultNode);
static void replace_vars_with_subplan_refs(Node *clause,
							   Index subvarno,
							   List *subplanTargetList);

/*****************************************************************************
 *
 *		SUBPLAN REFERENCES
 *
 *****************************************************************************/

/*
 * set_tlist_references
 *	  Modifies the target list of nodes in a plan to reference target lists
 *	  at lower levels.
 *
 * 'plan' is the plan whose target list and children's target lists will
 *		be modified
 *
 * Returns nothing of interest, but modifies internal fields of nodes.
 *
 */
void
set_tlist_references(Plan *plan)
{
	if (plan == NULL)
		return;

	if (IsA_Join(plan))
		set_join_tlist_references((Join *) plan);
	else if (IsA(plan, SeqScan) &&plan->lefttree &&
			 IsA_Noname(plan->lefttree))
		set_nonamescan_tlist_references((SeqScan *) plan);
	else if (IsA(plan, Sort))
		set_noname_tlist_references((Noname *) plan);
	else if (IsA(plan, Result))
		set_result_tlist_references((Result *) plan);
	else if (IsA(plan, Hash))
		set_tlist_references(plan->lefttree);
}

/*
 * set_join_tlist_references
 *	  Modifies the target list of a join node by setting the varnos and
 *	  varattnos to reference the target list of the outer and inner join
 *	  relations.
 *
 *	  Creates a target list for a join node to contain references by setting
 *	  varno values to OUTER or INNER and setting attno values to the
 *	  result domain number of either the corresponding outer or inner join
 *	  tuple.
 *
 * 'join' is a join plan node
 *
 * Returns nothing of interest, but modifies internal fields of nodes.
 *
 */
static void
set_join_tlist_references(Join *join)
{
	Plan	   *outer = ((Plan *) join)->lefttree;
	Plan	   *inner = ((Plan *) join)->righttree;
	List	   *outer_tlist = ((outer == NULL) ? NIL : outer->targetlist);
	List	   *inner_tlist = ((inner == NULL) ? NIL : inner->targetlist);
	List	   *new_join_targetlist = NIL;
	List	   *qptlist = ((Plan *) join)->targetlist;
	List	   *entry;

	foreach(entry, qptlist)
	{
		TargetEntry *xtl = (TargetEntry *) lfirst(entry);
		Node	   *joinvar = replace_clause_joinvar_refs(xtl->expr,
														  outer_tlist,
														  inner_tlist);

		new_join_targetlist = lappend(new_join_targetlist,
								  makeTargetEntry(xtl->resdom, joinvar));
	}

	((Plan *) join)->targetlist = new_join_targetlist;
	if (outer != NULL)
		set_tlist_references(outer);
	if (inner != NULL)
		set_tlist_references(inner);
}

/*
 * set_nonamescan_tlist_references
 *	  Modifies the target list of a node that scans a noname relation (i.e., a
 *	  sort or hash node) so that the varnos refer to the child noname.
 *
 * 'nonamescan' is a seqscan node
 *
 * Returns nothing of interest, but modifies internal fields of nodes.
 *
 */
static void
set_nonamescan_tlist_references(SeqScan *nonamescan)
{
	Noname	   *noname = (Noname *) ((Plan *) nonamescan)->lefttree;

	((Plan *) nonamescan)->targetlist = tlist_noname_references(noname->nonameid,
									  ((Plan *) nonamescan)->targetlist);
	set_noname_tlist_references(noname);
}

/*
 * set_noname_tlist_references
 *	  The noname's vars are made consistent with (actually, identical to) the
 *	  modified version of the target list of the node from which noname node
 *	  receives its tuples.
 *
 * 'noname' is a noname (e.g., sort, hash) plan node
 *
 * Returns nothing of interest, but modifies internal fields of nodes.
 *
 */
static void
set_noname_tlist_references(Noname *noname)
{
	Plan	   *source = ((Plan *) noname)->lefttree;

	if (source != NULL)
	{
		set_tlist_references(source);
		((Plan *) noname)->targetlist = copy_vars(((Plan *) noname)->targetlist,
												  (source)->targetlist);
	}
	else
		elog(ERROR, "calling set_noname_tlist_references with empty lefttree");
}

/*
 * join_references
 *	   Creates a new set of join clauses by changing the varno/varattno
 *	   values of variables in the clauses to reference target list values
 *	   from the outer and inner join relation target lists.
 *	   This is just an external interface for replace_clause_joinvar_refs.
 *
 * 'clauses' is the list of join clauses
 * 'outer_tlist' is the target list of the outer join relation
 * 'inner_tlist' is the target list of the inner join relation
 *
 * Returns the new join clauses.  The original clause structure is
 * not modified.
 *
 */
List *
join_references(List *clauses,
				List *outer_tlist,
				List *inner_tlist)
{
	return (List *) replace_clause_joinvar_refs((Node *) clauses,
												outer_tlist,
												inner_tlist);
}

/*
 * index_outerjoin_references
 *	  Given a list of join clauses, replace the operand corresponding to the
 *	  outer relation in the join with references to the corresponding target
 *	  list element in 'outer_tlist' (the outer is rather obscurely
 *	  identified as the side that doesn't contain a var whose varno equals
 *	  'inner_relid').
 *
 *	  As a side effect, the operator is replaced by the regproc id.
 *
 * 'inner_indxqual' is the list of join clauses (so-called because they
 * are used as qualifications for the inner (inbex) scan of a nestloop)
 *
 * Returns the new list of clauses.
 *
 */
List *
index_outerjoin_references(List *inner_indxqual,
						   List *outer_tlist,
						   Index inner_relid)
{
	List	   *t_list = NIL;
	Expr	   *temp = NULL;
	List	   *t_clause = NIL;
	Expr	   *clause = NULL;

	foreach(t_clause, inner_indxqual)
	{
		clause = lfirst(t_clause);

		/*
		 * if inner scan on the right.
		 */
		if (OperandIsInner((Node *) get_rightop(clause), inner_relid))
		{
			Var		   *joinvar = (Var *)
			replace_clause_joinvar_refs((Node *) get_leftop(clause),
										outer_tlist,
										NIL);

			temp = make_opclause(replace_opid((Oper *) ((Expr *) clause)->oper),
								 joinvar,
								 get_rightop(clause));
			t_list = lappend(t_list, temp);
		}
		else
		{
			/* inner scan on left */
			Var		   *joinvar = (Var *)
			replace_clause_joinvar_refs((Node *) get_rightop(clause),
										outer_tlist,
										NIL);

			temp = make_opclause(replace_opid((Oper *) ((Expr *) clause)->oper),
								 get_leftop(clause),
								 joinvar);
			t_list = lappend(t_list, temp);
		}

	}
	return t_list;
}

/*
 * replace_clause_joinvar_refs
 * replace_joinvar_refs
 *
 *	  Replaces all variables within a join clause with a new var node
 *	  whose varno/varattno fields contain a reference to a target list
 *	  element from either the outer or inner join relation.
 *
 * 'clause' is the join clause
 * 'outer_tlist' is the target list of the outer join relation
 * 'inner_tlist' is the target list of the inner join relation
 *
 * Returns the new join clause.
 * NB: it is critical that the original clause structure not be modified!
 * The changes must be applied to a copy.
 *
 * XXX the current implementation does not copy unchanged primitive
 * nodes; they remain shared with the original.  Is this safe?
 */
static Node *
replace_clause_joinvar_refs(Node *clause,
							List *outer_tlist,
							List *inner_tlist)
{
	if (clause == NULL)
		return NULL;
	if (IsA(clause, Var))
	{
		Var		   *temp = replace_joinvar_refs((Var *) clause,
												outer_tlist, inner_tlist);

		if (temp != NULL)
			return (Node *) temp;
		else
			return clause;
	}
	else if (single_node(clause))
		return clause;
	else if (and_clause(clause))
	{
		return (Node *) make_andclause((List *)
			replace_clause_joinvar_refs((Node *) ((Expr *) clause)->args,
										outer_tlist,
										inner_tlist));
	}
	else if (or_clause(clause))
	{
		return (Node *) make_orclause((List *)
			replace_clause_joinvar_refs((Node *) ((Expr *) clause)->args,
										outer_tlist,
										inner_tlist));
	}
	else if (IsA(clause, ArrayRef))
	{
		ArrayRef   *oldnode = (ArrayRef *) clause;
		ArrayRef   *newnode = makeNode(ArrayRef);

		newnode->refattrlength = oldnode->refattrlength;
		newnode->refelemlength = oldnode->refelemlength;
		newnode->refelemtype = oldnode->refelemtype;
		newnode->refelembyval = oldnode->refelembyval;
		newnode->refupperindexpr = (List *)
			replace_clause_joinvar_refs((Node *) oldnode->refupperindexpr,
										outer_tlist,
										inner_tlist);
		newnode->reflowerindexpr = (List *)
			replace_clause_joinvar_refs((Node *) oldnode->reflowerindexpr,
										outer_tlist,
										inner_tlist);
		newnode->refexpr =
			replace_clause_joinvar_refs(oldnode->refexpr,
										outer_tlist,
										inner_tlist);
		newnode->refassgnexpr =
			replace_clause_joinvar_refs(oldnode->refassgnexpr,
										outer_tlist,
										inner_tlist);

		return (Node *) newnode;
	}
	else if (is_funcclause(clause))
	{
		return (Node *) make_funcclause(
										(Func *) ((Expr *) clause)->oper,
									(List *) replace_clause_joinvar_refs(
										(Node *) ((Expr *) clause)->args,
															 outer_tlist,
														   inner_tlist));
	}
	else if (not_clause(clause))
	{
		return (Node *) make_notclause((Expr *)
									   replace_clause_joinvar_refs(
							  (Node *) get_notclausearg((Expr *) clause),
															 outer_tlist,
														   inner_tlist));
	}
	else if (is_opclause(clause))
	{
		return (Node *) make_opclause(
						  replace_opid((Oper *) ((Expr *) clause)->oper),
									  (Var *) replace_clause_joinvar_refs(
									(Node *) get_leftop((Expr *) clause),
															 outer_tlist,
															inner_tlist),
									  (Var *) replace_clause_joinvar_refs(
								   (Node *) get_rightop((Expr *) clause),
															 outer_tlist,
														   inner_tlist));
	}
	else if (IsA(clause, List))
	{
		List	   *t_list = NIL;
		List	   *subclause;

		foreach(subclause, (List *) clause)
		{
			t_list = lappend(t_list,
						   replace_clause_joinvar_refs(lfirst(subclause),
													   outer_tlist,
													   inner_tlist));
		}
		return (Node *) t_list;
	}
	else if (is_subplan(clause))
	{
		/* This is a tad wasteful of space, but it works... */
		Expr	   *newclause = (Expr *) copyObject(clause);

		newclause->args = (List *)
			replace_clause_joinvar_refs((Node *) newclause->args,
										outer_tlist,
										inner_tlist);
		((SubPlan *) newclause->oper)->sublink->oper = (List *)
			replace_clause_joinvar_refs(
				   (Node *) ((SubPlan *) newclause->oper)->sublink->oper,
										outer_tlist,
										inner_tlist);
		return (Node *) newclause;
	}
	else if (IsA(clause, CaseExpr))
	{
		CaseExpr   *oldnode = (CaseExpr *) clause;
		CaseExpr   *newnode = makeNode(CaseExpr);

		newnode->casetype = oldnode->casetype;
		newnode->arg = oldnode->arg;	/* XXX should always be null
										 * anyway ... */
		newnode->args = (List *)
			replace_clause_joinvar_refs((Node *) oldnode->args,
										outer_tlist,
										inner_tlist);
		newnode->defresult =
			replace_clause_joinvar_refs(oldnode->defresult,
										outer_tlist,
										inner_tlist);

		return (Node *) newnode;
	}
	else if (IsA(clause, CaseWhen))
	{
		CaseWhen   *oldnode = (CaseWhen *) clause;
		CaseWhen   *newnode = makeNode(CaseWhen);

		newnode->expr =
			replace_clause_joinvar_refs(oldnode->expr,
										outer_tlist,
										inner_tlist);
		newnode->result =
			replace_clause_joinvar_refs(oldnode->result,
										outer_tlist,
										inner_tlist);

		return (Node *) newnode;
	}
	else
	{
		elog(ERROR, "replace_clause_joinvar_refs: unsupported clause %d",
			 nodeTag(clause));
		return NULL;
	}
}

static Var *
replace_joinvar_refs(Var *var, List *outer_tlist, List *inner_tlist)
{
	Resdom	   *outer_resdom;

	outer_resdom = tlist_member(var, outer_tlist);

	if (outer_resdom != NULL && IsA(outer_resdom, Resdom))
	{
		return (makeVar(OUTER,
						outer_resdom->resno,
						var->vartype,
						var->vartypmod,
						0,
						var->varnoold,
						var->varoattno));
	}
	else
	{
		Resdom	   *inner_resdom;

		inner_resdom = tlist_member(var, inner_tlist);
		if (inner_resdom != NULL && IsA(inner_resdom, Resdom))
		{
			return (makeVar(INNER,
							inner_resdom->resno,
							var->vartype,
							var->vartypmod,
							0,
							var->varnoold,
							var->varoattno));
		}
	}
	return (Var *) NULL;
}

/*
 * tlist_noname_references
 *	  Creates a new target list for a node that scans a noname relation,
 *	  setting the varnos to the id of the noname relation and setting varids
 *	  if necessary (varids are only needed if this is a targetlist internal
 *	  to the tree, in which case the targetlist entry always contains a var
 *	  node, so we can just copy it from the noname).
 *
 * 'nonameid' is the id of the noname relation
 * 'tlist' is the target list to be modified
 *
 * Returns new target list
 *
 */
static List *
tlist_noname_references(Oid nonameid,
						List *tlist)
{
	List	   *t_list = NIL;
	TargetEntry *noname = (TargetEntry *) NULL;
	TargetEntry *xtl = NULL;
	List	   *entry;