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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 1.13 1999/02/13 23:16:16 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 HashInfo *match_hashop_hashinfo(Oid hashop, List *hashinfo_list);
/*
* group_clauses_by_hashop
* If a join clause node in 'restrictinfo_list' is hashjoinable, store
* it within a hashinfo node containing other clause nodes with the same
* hash operator.
*
* 'restrictinfo_list' is the list of restrictinfo nodes
* 'inner_relid' is the relid of the inner join relation
*
* Returns the new list of hashinfo nodes.
*
*/
List *
group_clauses_by_hashop(List *restrictinfo_list,
int inner_relid)
{
List *hashinfo_list = NIL;
RestrictInfo *restrictinfo = (RestrictInfo *) NULL;
List *i = NIL;
Oid hashjoinop = 0;
foreach(i, restrictinfo_list)
{
restrictinfo = (RestrictInfo *) lfirst(i);
hashjoinop = restrictinfo->hashjoinoperator;
/*
* Create a new hashinfo node and add it to 'hashinfo_list' if one
* does not yet exist for this hash operator.
*/
if (hashjoinop)
{
HashInfo *xhashinfo = (HashInfo *) NULL;
Expr *clause = restrictinfo->clause;
Var *leftop = get_leftop(clause);
Var *rightop = get_rightop(clause);
JoinKey *joinkey = (JoinKey *) NULL;
xhashinfo = match_hashop_hashinfo(hashjoinop, hashinfo_list);
if (inner_relid == leftop->varno)
{
joinkey = makeNode(JoinKey);
joinkey->outer = rightop;
joinkey->inner = leftop;
}
else
{
joinkey = makeNode(JoinKey);
joinkey->outer = leftop;
joinkey->inner = rightop;
}
if (xhashinfo == NULL)
{
xhashinfo = makeNode(HashInfo);
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(joinkey, 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 HashInfo *
match_hashop_hashinfo(Oid hashop, List *hashinfo_list)
{
Oid key = 0;
HashInfo *xhashinfo = (HashInfo *) NULL;
List *i = NIL;
foreach(i, hashinfo_list)
{
xhashinfo = (HashInfo *) lfirst(i);
key = xhashinfo->hashop;
if (hashop == key)
{ /* found */
return xhashinfo; /* should be a hashinfo node ! */
}
}
return (HashInfo *) NIL;
}
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