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77 lines
2.0 KiB
C
77 lines
2.0 KiB
C
/*-------------------------------------------------------------------------
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*
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* joininfo.c
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* JoinInfo node manipulation routines
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*
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/util/joininfo.c,v 1.29 2001/03/22 03:59:39 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "optimizer/joininfo.h"
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static JoinInfo *joininfo_member(List *join_relids, List *joininfo_list);
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/*
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* joininfo_member
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* Determines whether a node has already been created for a join
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* between a set of join relations and the relation described by
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* 'joininfo_list'.
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*
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* 'join_relids' is a list of relids corresponding to the join relation
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* 'joininfo_list' is the list of joininfo nodes against which this is
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* checked
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*
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* Returns the corresponding node in 'joininfo_list' if such a node
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* exists.
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*
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*/
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static JoinInfo *
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joininfo_member(List *join_relids, List *joininfo_list)
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{
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List *i;
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foreach(i, joininfo_list)
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{
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JoinInfo *joininfo = (JoinInfo *) lfirst(i);
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if (sameseti(join_relids, joininfo->unjoined_relids))
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return joininfo;
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}
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return NULL;
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}
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/*
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* find_joininfo_node
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* Find the joininfo node within a relation entry corresponding
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* to a join between 'this_rel' and the relations in 'join_relids'.
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* A new node is created and added to the relation entry's joininfo
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* field if the desired one can't be found.
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*
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* Returns a joininfo node.
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*
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*/
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JoinInfo *
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find_joininfo_node(RelOptInfo *this_rel, Relids join_relids)
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{
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JoinInfo *joininfo = joininfo_member(join_relids,
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this_rel->joininfo);
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if (joininfo == NULL)
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{
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joininfo = makeNode(JoinInfo);
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joininfo->unjoined_relids = join_relids;
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joininfo->jinfo_restrictinfo = NIL;
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this_rel->joininfo = lcons(joininfo, this_rel->joininfo);
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}
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return joininfo;
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}
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