PostgreSQL/src/backend/optimizer/plan/setrefs.c

/*-------------------------------------------------------------------------
 *
 * setrefs.c--
 *    Routines to change varno/attno entries to contain references
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /cvsroot/pgsql/src/backend/optimizer/plan/setrefs.c,v 1.1.1.1 1996/07/09 06:21:37 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "nodes/pg_list.h"
#include "nodes/plannodes.h"
#include "nodes/primnodes.h"
#include "nodes/relation.h"

#include "utils/elog.h"
#include "nodes/nodeFuncs.h"
#include "nodes/makefuncs.h"

#include "optimizer/internal.h"
#include "optimizer/clauses.h"
#include "optimizer/clauseinfo.h"
#include "optimizer/keys.h"
#include "optimizer/planmain.h"
#include "optimizer/tlist.h"
#include "optimizer/var.h"
#include "optimizer/tlist.h"

static void set_join_tlist_references(Join *join);
static void set_tempscan_tlist_references(SeqScan *tempscan);
static void set_temp_tlist_references(Temp *temp);
static List *replace_clause_joinvar_refs(Expr *clause,
			     List *outer_tlist, List *inner_tlist);
static List *replace_subclause_joinvar_refs(List *clauses,
				List *outer_tlist, List *inner_tlist);
static Var *replace_joinvar_refs(Var *var, List *outer_tlist, List *inner_tlist);
static List *tlist_temp_references(Oid tempid, List *tlist);
static void replace_result_clause(List *clause, List *subplanTargetList);
static bool OperandIsInner(Node *opnd, int inner_relid);
static void replace_agg_clause(Node *expr, List *targetlist);

/*****************************************************************************
 *     
 *     	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_Temp(plan->lefttree)) {
	set_tempscan_tlist_references((SeqScan*)plan);
    } else if (IsA(plan,Sort)) {
	set_temp_tlist_references ((Temp*)plan);
    } else if (IsA(plan,Result)) {
	set_result_tlist_references((Result*)plan);
    } else if (IsA(plan,Hash)) {
	set_tlist_references(plan->lefttree);
    } else if (IsA(plan,Choose)) {
	List *x;
	foreach (x, ((Choose*)plan)->chooseplanlist) {
	    set_tlist_references((Plan*)lfirst(x));
	}
    }
}

/*    
 * 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 	*new_join_targetlist = NIL;
    TargetEntry *temp = (TargetEntry *)NULL;
    List  	*entry = NIL;
    List	*inner_tlist = NULL;
    List	*outer_tlist = NULL;
    TargetEntry *xtl = 	(TargetEntry *)NULL;
    List	*qptlist = ((Plan*)join)->targetlist;

    foreach(entry, qptlist) {
	List *joinvar;

	xtl = (TargetEntry *)lfirst(entry);
	inner_tlist = ((inner==NULL) ? NIL : inner->targetlist);
	outer_tlist = ((outer==NULL) ? NIL : outer->targetlist);
	joinvar = replace_clause_joinvar_refs((Expr*)get_expr(xtl),
					      outer_tlist,
					      inner_tlist);

	temp = MakeTLE(xtl->resdom, (Node*)joinvar);
	new_join_targetlist = lappend(new_join_targetlist,temp);
    }
	
    ((Plan*)join)->targetlist = new_join_targetlist;
    if (outer!=NULL)
	set_tlist_references(outer);
    if (inner!=NULL)
	set_tlist_references(inner);
}

/*    
 * set-tempscan-tlist-references--
 *    Modifies the target list of a node that scans a temp relation (i.e., a
 *    sort or hash node) so that the varnos refer to the child temporary.
 *    
 * 'tempscan' is a seqscan node
 *    
 * Returns nothing of interest, but modifies internal fields of nodes.
 *    
 */
static void
set_tempscan_tlist_references(SeqScan *tempscan)
{
    Temp *temp = (Temp*)((Plan*)tempscan)->lefttree;

    ((Plan*)tempscan)->targetlist =
	tlist_temp_references(temp->tempid,
			      ((Plan*)tempscan)->targetlist);
    set_temp_tlist_references(temp);
}

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

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

/*    
 * join-references--
 *     Creates a new set of join clauses by replacing the varno/varattno
 *     values of variables in the clauses to reference target list values
 *     from the outer and inner join relation target lists.
 *    
 * '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.
 *    
 */
List *
join_references(List *clauses,
		List *outer_tlist,
		List *inner_tlist)
{
    return (replace_subclause_joinvar_refs(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((Expr*)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((Expr*)get_rightop(clause),
					    outer_tlist,
					    NIL);
	    temp = make_opclause(replace_opid((Oper*)((Expr*)clause)->oper),
				 joinvar,
				 get_leftop(clause));
	    t_list = lappend(t_list,temp);
	} 
	
    }
    return(t_list);
}

/*    
 * replace-clause-joinvar-refs
 * replace-subclause-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.
 *    
 */
static List *
replace_clause_joinvar_refs(Expr *clause,
			    List *outer_tlist,
			    List *inner_tlist)
{
    List *temp = NULL;

    if(IsA (clause,Var)) {
	temp = (List*)replace_joinvar_refs((Var*)clause,
					   outer_tlist,inner_tlist);
	if(temp)
	    return(temp);
	else
	    if (clause != NULL)
		return((List*)clause);
	    else
		return(NIL);
    } else if (single_node((Node*)clause)) {
	return ((List*)clause);
    } else if (or_clause((Node*)clause)) {
	List *orclause =
	    replace_subclause_joinvar_refs(((Expr*)clause)->args,
					   outer_tlist,
					   inner_tlist);
	return ((List*)make_orclause(orclause));
    } else if (IsA(clause,ArrayRef)) {
	ArrayRef *aref = (ArrayRef *)clause;

	temp = replace_subclause_joinvar_refs(aref->refupperindexpr,
					      outer_tlist,
					      inner_tlist);
	aref->refupperindexpr = (List*)temp;
	temp = replace_subclause_joinvar_refs(aref->reflowerindexpr,
					      outer_tlist,
					      inner_tlist);
	aref->reflowerindexpr = (List*)temp;
	temp = replace_clause_joinvar_refs((Expr*)aref->refexpr,
					   outer_tlist,
					   inner_tlist);
	aref->refexpr = (Node*)temp;

	/*
	 *  no need to set refassgnexpr.  we only set that in the
	 *  target list on replaces, and this is an array reference
	 *  in the qualification.  if we got this far, it's 0x0 in
	 *  the ArrayRef structure 'clause'.
	 */

	return((List*)clause);
    } else if (is_funcclause((Node*)clause)) {
	List *funcclause =
	    replace_subclause_joinvar_refs(((Expr*)clause)->args,
					   outer_tlist,
					   inner_tlist);
	return ((List*)make_funcclause((Func*)((Expr*)clause)->oper,
				       funcclause));
    } else if (not_clause((Node*)clause)) {
	List *notclause =
	    replace_clause_joinvar_refs(get_notclausearg(clause),
					outer_tlist,
					inner_tlist);
	return ((List*)make_notclause((Expr*)notclause));
    } else if (is_opclause((Node*)clause)) {
	Var *leftvar =
	    (Var*)replace_clause_joinvar_refs((Expr*)get_leftop(clause),
					     outer_tlist,
					     inner_tlist);
	Var *rightvar =
	    (Var*)replace_clause_joinvar_refs((Expr*)get_rightop(clause),
					     outer_tlist,
					     inner_tlist);
	return ((List*)make_opclause(replace_opid((Oper*)((Expr*)clause)->oper),
				     leftvar,
				     rightvar));
    }
    /* shouldn't reach here */
    return NULL;
}

static List *
replace_subclause_joinvar_refs(List *clauses,
			       List *outer_tlist,
			       List *inner_tlist)
{
    List *t_list = NIL;
    List *temp = NIL;
    List *clause = NIL;

    foreach (clause,clauses) {
	temp = replace_clause_joinvar_refs(lfirst(clause),
					   outer_tlist,
					   inner_tlist);
	t_list = lappend(t_list,temp);
    }
    return(t_list);
}

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

    outer_resdom= tlist_member(var,outer_tlist);

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

/*    
 * tlist-temp-references--
 *    Creates a new target list for a node that scans a temp relation,
 *    setting the varnos to the id of the temp 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 temp).
 *    
 * 'tempid' is the id of the temp relation
 * 'tlist' is the target list to be modified
 *    
 * Returns new target list
 *    
 */
static List *
tlist_temp_references(Oid tempid, 
		      List *tlist)
{
    List *t_list = NIL;
    TargetEntry *temp = (TargetEntry *)NULL;
    TargetEntry *xtl = NULL;
    List *entry;
     
    foreach (entry, tlist) {
	AttrNumber oattno;

	xtl = lfirst(entry);
	if (IsA(get_expr(xtl), Var))
	    oattno = ((Var*)xtl->expr)->varoattno;
	else
	    oattno = 0;
	 
	temp = MakeTLE(xtl->resdom,
		       (Node*)makeVar(tempid,
				      xtl->resdom->resno,
				      xtl->resdom->restype,
				      tempid,
				      oattno));
	 
	t_list = lappend(t_list,temp);
    }
    return(t_list);
}

/*---------------------------------------------------------
 *
 * set_result_tlist_references
 *
 * Change the target list of a Result node, so that it correctly
 * addresses the tuples returned by its left tree subplan.
 *
 * NOTE:
 *  1) we ignore the right tree! (in the current implementation
 *     it is always nil
 *  2) this routine will probably *NOT* work with nested dot
 *     fields....
 */
void
set_result_tlist_references(Result *resultNode)
{
    Plan *subplan;
    List *resultTargetList;
    List *subplanTargetList;
    List *t;
    TargetEntry *entry;
    Expr *expr;

    resultTargetList= ((Plan*)resultNode)->targetlist;

    /*
     * NOTE: we only consider the left tree subplan.
     * This is usually a seq scan.
     */
    subplan = ((Plan*)resultNode)->lefttree;
    if (subplan != NULL) {
	subplanTargetList = subplan->targetlist;
    } else {
	subplanTargetList = NIL;
    }

    /*
     * now for traverse all the entris of the target list.
     * These should be of the form (Resdom_Node Expression).
     * For every expression clause, call "replace_result_clause()"
     * to appropriatelly change all the Var nodes.
     */
    foreach (t, resultTargetList) {
	entry = (TargetEntry *)lfirst(t);
	expr = (Expr*) get_expr(entry);
	replace_result_clause((List*)expr, subplanTargetList);
    }
}

/*---------------------------------------------------------
 *
 * replace_result_clause
 *
 * This routine is called from set_result_tlist_references().
 * and modifies the expressions of the target list of a Result
 * node so that all Var nodes reference the target list of its subplan.
 * 
 */
static void
replace_result_clause(List *clause,
		      List *subplanTargetList) /* target list of the
						  subplan */
{
    List *t;
    List *subClause;
    TargetEntry *subplanVar;

    if (IsA(clause,Var)) {
	/*
	 * Ha! A Var node!
	 */
	subplanVar = match_varid((Var*)clause, subplanTargetList);
	/*
	 * Change the varno & varattno fields of the
	 * var node.
	 *
	 */
	((Var*)clause)->varno = (Index)OUTER;
	((Var*)clause)->varattno = subplanVar->resdom->resno;
    } else if (is_funcclause((Node*)clause)) {
	/*
	 * This is a function. Recursively call this routine
	 * for its arguments...
	 */
	subClause = ((Expr*)clause)->args;
	foreach (t, subClause) {
	    replace_result_clause(lfirst(t),subplanTargetList);
	   }
    } else if (IsA(clause,ArrayRef)) {
	ArrayRef *aref = (ArrayRef *)clause;
	/*
	 * This is an arrayref. Recursively call this routine
	 * for its expression and its index expression...
	 */
	subClause = aref->refupperindexpr;
	foreach (t, subClause) {
	    replace_result_clause(lfirst(t),subplanTargetList);
	}
	subClause = aref->reflowerindexpr;
	foreach (t, subClause) {
	    replace_result_clause(lfirst(t),subplanTargetList);
	}
	replace_result_clause((List*)aref->refexpr,
			      subplanTargetList);
	replace_result_clause((List*)aref->refassgnexpr,
			      subplanTargetList);
    } else if (is_opclause((Node*)clause)) {
	/*
	 * This is an operator. Recursively call this routine
	 * for both its left and right operands
	 */
	subClause = (List*)get_leftop((Expr*)clause);
	replace_result_clause(subClause,subplanTargetList);
	subClause = (List*)get_rightop((Expr*)clause);
	replace_result_clause(subClause,subplanTargetList);
    } else if (IsA(clause,Param) || IsA(clause,Const)) {
	/* do nothing! */
    } else {
	/*
	 * Ooops! we can not handle that!
	 */
	elog(WARN,"replace_result_clause: Can not handle this tlist!\n");
    }
}

static
bool OperandIsInner(Node *opnd, int inner_relid)
{
    /*
     * Can be the inner scan if its a varnode or a function and the
     * inner_relid is equal to the varnode's var number or in the 
     * case of a function the first argument's var number (all args
     * in a functional index are from the same relation).
     */
    if ( IsA (opnd,Var) && 
	(inner_relid == ((Var*)opnd)->varno) )
	{
	    return true;
	}
    if (is_funcclause(opnd))
	{
	    List *firstArg = lfirst(((Expr*)opnd)->args);

	    if ( IsA (firstArg,Var) &&
		(inner_relid == ((Var*)firstArg)->varno) )
		{
		    return true;
		}
	}
    return false;
}

/*****************************************************************************
 *
 *****************************************************************************/

/*---------------------------------------------------------
 *
 * set_agg_tlist_references -
 *    changes the target list of an Agg node so that it points to
 *    the tuples returned by its left tree subplan.
 *
 */
void
set_agg_tlist_references(Agg *aggNode)
{
    List *aggTargetList;
    List *subplanTargetList;
    List *tl;

    aggTargetList = aggNode->plan.targetlist;
    subplanTargetList = aggNode->plan.lefttree->targetlist;

    foreach (tl, aggTargetList) {
	TargetEntry *tle = lfirst(tl);

	replace_agg_clause(tle->expr, subplanTargetList);
    }
}

void
set_agg_agglist_references(Agg *aggNode)
{
    List *subplanTargetList;
    Aggreg **aggs;
    int i;

    aggs = aggNode->aggs;
    subplanTargetList = aggNode->plan.lefttree->targetlist;

    for (i = 0; i < aggNode->numAgg; i++) {
	replace_agg_clause(aggs[i]->target, subplanTargetList);
    }
}

static void
replace_agg_clause(Node *clause, List *subplanTargetList)
{
    List *t;
    TargetEntry *subplanVar;

    if (IsA(clause,Var)) {
	/*
	 * Ha! A Var node!
	 */
	subplanVar = match_varid((Var*)clause, subplanTargetList);
	/*
	 * Change the varno & varattno fields of the
	 * var node.
	 *
	 */
	((Var*)clause)->varattno = subplanVar->resdom->resno;
    } else if (is_funcclause(clause)) {
	/*
	 * This is a function. Recursively call this routine
	 * for its arguments...
	 */
	foreach (t, ((Expr*)clause)->args) {
	    replace_agg_clause(lfirst(t), subplanTargetList);
	   }
    } else if (IsA(clause,Aggreg)) {
	replace_agg_clause(((Aggreg*)clause)->target, subplanTargetList);
    } else if (IsA(clause,ArrayRef)) {
	ArrayRef *aref = (ArrayRef *)clause;

	/*
	 * This is an arrayref. Recursively call this routine
	 * for its expression and its index expression...
	 */
	foreach (t, aref->refupperindexpr) {
	    replace_agg_clause(lfirst(t),subplanTargetList);
	}
	foreach (t, aref->reflowerindexpr) {
	    replace_agg_clause(lfirst(t),subplanTargetList);
	}
	replace_agg_clause(aref->refexpr, subplanTargetList);
	replace_agg_clause(aref->refassgnexpr, subplanTargetList);
    } else if (is_opclause(clause)) {
	/*
	 * This is an operator. Recursively call this routine
	 * for both its left and right operands
	 */
	replace_agg_clause((Node*)get_leftop((Expr*)clause),
			   subplanTargetList);
	replace_agg_clause((Node*)get_rightop((Expr*)clause),
			   subplanTargetList);
    } else if (IsA(clause,Param) || IsA(clause,Const)) {
	/* do nothing! */
    } else {
	/*
	 * Ooops! we can not handle that!
	 */
	elog(WARN,"replace_agg_clause: Can not handle this tlist!\n");
    }

}