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/*-------------------------------------------------------------------------
*
* ordering.c--
* Routines to manipulate and compare merge and path orderings
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/Attic/ordering.c,v 1.6 1997/09/08 21:45:52 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include <sys/types.h>
#include "postgres.h"
#include "optimizer/internal.h"
#include "optimizer/ordering.h"
static bool equal_sortops_order(Oid *ordering1, Oid *ordering2);
/*
* equal-path-path-ordering--
* Returns t iff two path orderings are equal.
*
*/
bool
equal_path_path_ordering(PathOrder *path_ordering1,
PathOrder *path_ordering2)
{
if (path_ordering1 == path_ordering2)
return true;
if (!path_ordering1 || !path_ordering2)
return false;
if (path_ordering1->ordtype == MERGE_ORDER &&
path_ordering2->ordtype == MERGE_ORDER)
{
return equal(path_ordering1->ord.merge, path_ordering2->ord.merge);
}
else if (path_ordering1->ordtype == SORTOP_ORDER &&
path_ordering2->ordtype == SORTOP_ORDER)
{
return
(equal_sortops_order(path_ordering1->ord.sortop,
path_ordering2->ord.sortop));
}
else if (path_ordering1->ordtype == MERGE_ORDER &&
path_ordering2->ordtype == SORTOP_ORDER)
{
return (path_ordering2->ord.sortop &&
(path_ordering1->ord.merge->left_operator ==
path_ordering2->ord.sortop[0]));
}
else
{
return (path_ordering1->ord.sortop &&
(path_ordering1->ord.sortop[0] ==
path_ordering2->ord.merge->left_operator));
}
}
/*
* equal-path-merge-ordering--
* Returns t iff a path ordering is usable for ordering a merge join.
*
* XXX Presently, this means that the first sortop of the path matches
* either of the merge sortops. Is there a "right" and "wrong"
* sortop to match?
*
*/
bool
equal_path_merge_ordering(Oid *path_ordering,
MergeOrder *merge_ordering)
{
if (path_ordering == NULL || merge_ordering == NULL)
return (false);
if (path_ordering[0] == merge_ordering->left_operator ||
path_ordering[0] == merge_ordering->right_operator)
return (true);
else
return (false);
}
/*
* equal-merge-merge-ordering--
* Returns t iff two merge orderings are equal.
*
*/
bool
equal_merge_merge_ordering(MergeOrder *merge_ordering1,
MergeOrder *merge_ordering2)
{
return (equal(merge_ordering1, merge_ordering2));
}
/*****************************************************************************
*
*****************************************************************************/
/*
* equal_sort_ops_order -
* Returns true iff the sort operators are in the same order.
*/
static bool
equal_sortops_order(Oid *ordering1, Oid *ordering2)
{
int i = 0;
if (ordering1 == NULL || ordering2 == NULL)
return (ordering1 == ordering2);
while (ordering1[i] != 0 && ordering2[i] != 0)
{
if (ordering1[i] != ordering2[i])
break;
i++;
}
return (ordering1[i] == 0 && ordering2[i] == 0);
}
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