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/*-------------------------------------------------------------------------
*
* hashutils.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/hashutils.c,v 1.4 1997/09/08 21:44:51 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"
static HInfo *match_hashop_hashinfo(Oid hashop, List *hashinfo_list);
/*
* group-clauses-by-hashop--
* If a join clause node in 'clauseinfo-list' is hashjoinable, store
* it within a hashinfo node containing other clause nodes with the same
* hash operator.
*
* 'clauseinfo-list' is the list of clauseinfo nodes
* 'inner-relid' is the relid of the inner join relation
*
* Returns the new list of hashinfo nodes.
*
*/
List *
group_clauses_by_hashop(List *clauseinfo_list,
int inner_relid)
{
List *hashinfo_list = NIL;
CInfo *clauseinfo = (CInfo *) NULL;
List *i = NIL;
Oid hashjoinop = 0;
foreach(i, clauseinfo_list)
{
clauseinfo = (CInfo *) lfirst(i);
hashjoinop = clauseinfo->hashjoinoperator;
/*
* Create a new hashinfo node and add it to 'hashinfo-list' if one
* does not yet exist for this hash operator.
*/
if (hashjoinop)
{
HInfo *xhashinfo = (HInfo *) NULL;
Expr *clause = clauseinfo->clause;
Var *leftop = get_leftop(clause);
Var *rightop = get_rightop(clause);
JoinKey *keys = (JoinKey *) NULL;
xhashinfo =
match_hashop_hashinfo(hashjoinop, hashinfo_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 (xhashinfo == NULL)
{
xhashinfo = makeNode(HInfo);
xhashinfo->hashop = hashjoinop;
xhashinfo->jmethod.jmkeys = NIL;
xhashinfo->jmethod.clauses = NIL;
/* XXX was push */
hashinfo_list = lappend(hashinfo_list, xhashinfo);
hashinfo_list = nreverse(hashinfo_list);
}
xhashinfo->jmethod.clauses =
lcons(clause, xhashinfo->jmethod.clauses);
xhashinfo->jmethod.jmkeys =
lcons(keys, xhashinfo->jmethod.jmkeys);
}
}
return (hashinfo_list);
}
/*
* match-hashop-hashinfo--
* Searches the list 'hashinfo-list' for a hashinfo node whose hash op
* field equals 'hashop'.
*
* Returns the node if it exists.
*
*/
static HInfo *
match_hashop_hashinfo(Oid hashop, List *hashinfo_list)
{
Oid key = 0;
HInfo *xhashinfo = (HInfo *) NULL;
List *i = NIL;
foreach(i, hashinfo_list)
{
xhashinfo = (HInfo *) lfirst(i);
key = xhashinfo->hashop;
if (hashop == key)
{ /* found */
return (xhashinfo); /* should be a hashinfo node ! */
}
}
return ((HInfo *) NIL);
}
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