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/*-------------------------------------------------------------------------
*
* mergeutils.c--
* Utilities for finding applicable merge clauses and pathkeys
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/mergeutils.c,v 1.3 1997/09/08 02:24:24 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "nodes/pg_list.h"
#include "nodes/relation.h"
#include "optimizer/internal.h"
#include "optimizer/paths.h"
#include "optimizer/clauses.h"
#include "optimizer/ordering.h"
/*
* group-clauses-by-order--
* If a join clause node in 'clauseinfo-list' is mergesortable, store
* it within a mergeinfo node containing other clause nodes with the same
* mergesort ordering.
*
* 'clauseinfo-list' is the list of clauseinfo nodes
* 'inner-relid' is the relid of the inner join relation
*
* Returns the new list of mergeinfo nodes.
*
*/
List *
group_clauses_by_order(List * clauseinfo_list,
int inner_relid)
{
List *mergeinfo_list = NIL;
List *xclauseinfo = NIL;
foreach(xclauseinfo, clauseinfo_list)
{
CInfo *clauseinfo = (CInfo *) lfirst(xclauseinfo);
MergeOrder *merge_ordering = clauseinfo->mergesortorder;
if (merge_ordering)
{
/*
* Create a new mergeinfo node and add it to 'mergeinfo-list'
* if one does not yet exist for this merge ordering.
*/
PathOrder p_ordering;
MInfo *xmergeinfo;
Expr *clause = clauseinfo->clause;
Var *leftop = get_leftop(clause);
Var *rightop = get_rightop(clause);
JoinKey *keys;
p_ordering.ordtype = MERGE_ORDER;
p_ordering.ord.merge = merge_ordering;
xmergeinfo =
match_order_mergeinfo(&p_ordering, mergeinfo_list);
if (inner_relid == leftop->varno)
{
keys = makeNode(JoinKey);
keys->outer = rightop;
keys->inner = leftop;
}
else
{
keys = makeNode(JoinKey);
keys->outer = leftop;
keys->inner = rightop;
}
if (xmergeinfo == NULL)
{
xmergeinfo = makeNode(MInfo);
xmergeinfo->m_ordering = merge_ordering;
mergeinfo_list = lcons(xmergeinfo,
mergeinfo_list);
}
((JoinMethod *) xmergeinfo)->clauses =
lcons(clause,
((JoinMethod *) xmergeinfo)->clauses);
((JoinMethod *) xmergeinfo)->jmkeys =
lcons(keys,
((JoinMethod *) xmergeinfo)->jmkeys);
}
}
return (mergeinfo_list);
}
/*
* match-order-mergeinfo--
* Searches the list 'mergeinfo-list' for a mergeinfo node whose order
* field equals 'ordering'.
*
* Returns the node if it exists.
*
*/
MInfo *
match_order_mergeinfo(PathOrder * ordering, List * mergeinfo_list)
{
MergeOrder *xmergeorder;
List *xmergeinfo = NIL;
foreach(xmergeinfo, mergeinfo_list)
{
MInfo *mergeinfo = (MInfo *) lfirst(xmergeinfo);
xmergeorder = mergeinfo->m_ordering;
if ((ordering->ordtype == MERGE_ORDER &&
equal_merge_merge_ordering(ordering->ord.merge, xmergeorder)) ||
(ordering->ordtype == SORTOP_ORDER &&
equal_path_merge_ordering(ordering->ord.sortop, xmergeorder)))
{
return (mergeinfo);
}
}
return ((MInfo *) NIL);
}
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