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586 lines
15 KiB
C
586 lines
15 KiB
C
/*-------------------------------------------------------------------------
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*
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* joinrels.c
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* Routines to determine which relations should be joined
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*
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* 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/path/joinrels.c,v 1.20 1999/02/13 23:16:18 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 "nodes/pg_list.h"
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#include "nodes/relation.h"
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#include "optimizer/internal.h"
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#include "optimizer/cost.h"
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#include "optimizer/paths.h"
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#include "optimizer/tlist.h"
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#include "optimizer/joininfo.h"
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#include "optimizer/pathnode.h"
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#ifdef USE_RIGHT_SIDED_PLANS
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bool _use_right_sided_plans_ = true;
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#else
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bool _use_right_sided_plans_ = false;
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#endif
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static List *find_clause_joins(Query *root, RelOptInfo *outer_rel, List *joininfo_list);
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static List *find_clauseless_joins(RelOptInfo *outer_rel, List *inner_rels);
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static RelOptInfo *init_join_rel(RelOptInfo *outer_rel, RelOptInfo *inner_rel, JoinInfo * joininfo);
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static List *new_join_tlist(List *tlist, List *other_relids,
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int first_resdomno);
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static List *new_joininfo_list(List *joininfo_list, List *join_relids);
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static void add_superrels(RelOptInfo *rel, RelOptInfo *super_rel);
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static bool nonoverlap_rels(RelOptInfo *rel1, RelOptInfo *rel2);
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static bool nonoverlap_sets(List *s1, List *s2);
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static void set_joinrel_size(RelOptInfo *joinrel, RelOptInfo *outer_rel, RelOptInfo *inner_rel,
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JoinInfo * jinfo);
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/*
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* find_join_rels
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* Find all possible joins for each of the outer join relations in
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* 'outer_rels'. A rel node is created for each possible join relation,
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* and the resulting list of nodes is returned. If at all possible, only
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* those relations for which join clauses exist are considered. If none
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* of these exist for a given relation, all remaining possibilities are
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* considered.
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*
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* 'outer_rels' is the list of rel nodes
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*
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* Returns a list of rel nodes corresponding to the new join relations.
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*/
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List *
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find_join_rels(Query *root, List *outer_rels)
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{
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List *joins = NIL;
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List *join_list = NIL;
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List *r = NIL;
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foreach(r, outer_rels)
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{
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RelOptInfo *outer_rel = (RelOptInfo *) lfirst(r);
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if (!(joins = find_clause_joins(root, outer_rel, outer_rel->joininfo)))
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{
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if (BushyPlanFlag)
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joins = find_clauseless_joins(outer_rel, outer_rels);
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else
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joins = find_clauseless_joins(outer_rel, root->base_rel_list);
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}
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join_list = nconc(join_list, joins);
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}
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return join_list;
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}
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/*
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* find_clause_joins
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* Determines whether joins can be performed between an outer relation
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* 'outer_rel' and those relations within 'outer_rel's joininfo nodes
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* (i.e., relations that participate in join clauses that 'outer_rel'
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* participates in). This is possible if all but one of the relations
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* contained within the join clauses of the joininfo node are already
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* contained within 'outer_rel'.
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*
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* 'outer_rel' is the relation entry for the outer relation
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* 'joininfo_list' is a list of join clauses which 'outer_rel'
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* participates in
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*
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* Returns a list of new join relations.
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*/
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static List *
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find_clause_joins(Query *root, RelOptInfo *outer_rel, List *joininfo_list)
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{
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List *join_list = NIL;
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List *i = NIL;
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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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RelOptInfo *rel;
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if (!joininfo->inactive)
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{
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List *other_rels = joininfo->otherrels;
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if (other_rels != NIL)
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{
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if (length(other_rels) == 1)
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{
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rel = init_join_rel(outer_rel,
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get_base_rel(root, lfirsti(other_rels)),
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joininfo);
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/* how about right-sided plan ? */
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if (_use_right_sided_plans_ &&
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length(outer_rel->relids) > 1)
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{
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if (rel != NULL)
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join_list = lappend(join_list, rel);
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rel = init_join_rel(get_base_rel(root, lfirsti(other_rels)),
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outer_rel,
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joininfo);
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}
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}
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else if (BushyPlanFlag)
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{
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rel = init_join_rel(outer_rel,
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get_join_rel(root, other_rels),
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joininfo);
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}
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else
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rel = NULL;
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if (rel != NULL)
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join_list = lappend(join_list, rel);
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}
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}
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}
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return join_list;
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}
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/*
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* find_clauseless_joins
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* Given an outer relation 'outer_rel' and a list of inner relations
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* 'inner_rels', create a join relation between 'outer_rel' and each
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* member of 'inner_rels' that isn't already included in 'outer_rel'.
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*
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* Returns a list of new join relations.
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*/
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static List *
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find_clauseless_joins(RelOptInfo *outer_rel, List *inner_rels)
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{
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RelOptInfo *inner_rel;
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List *t_list = NIL;
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List *temp_node = NIL;
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List *i = NIL;
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foreach(i, inner_rels)
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{
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inner_rel = (RelOptInfo *) lfirst(i);
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if (nonoverlap_rels(inner_rel, outer_rel))
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{
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temp_node = lcons(init_join_rel(outer_rel,
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inner_rel,
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(JoinInfo *) NULL),
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NIL);
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t_list = nconc(t_list, temp_node);
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}
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}
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return t_list;
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}
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/*
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* init_join_rel
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* Creates and initializes a new join relation.
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*
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* 'outer_rel' and 'inner_rel' are relation nodes for the relations to be
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* joined
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* 'joininfo' is the joininfo node(join clause) containing both
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* 'outer_rel' and 'inner_rel', if any exists
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*
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* Returns the new join relation node.
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*/
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static RelOptInfo *
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init_join_rel(RelOptInfo *outer_rel, RelOptInfo *inner_rel, JoinInfo * joininfo)
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{
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RelOptInfo *joinrel = makeNode(RelOptInfo);
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List *joinrel_joininfo_list = NIL;
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List *new_outer_tlist;
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List *new_inner_tlist;
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/*
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* Create a new tlist by removing irrelevant elements from both tlists
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* of the outer and inner join relations and then merging the results
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* together.
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*/
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new_outer_tlist = new_join_tlist(outer_rel->targetlist, /* XXX 1-based attnos */
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inner_rel->relids, 1);
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new_inner_tlist = new_join_tlist(inner_rel->targetlist, /* XXX 1-based attnos */
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outer_rel->relids,
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length(new_outer_tlist) + 1);
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joinrel->relids = NIL;
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joinrel->indexed = false;
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joinrel->pages = 0;
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joinrel->tuples = 0;
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joinrel->width = 0;
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/* joinrel->targetlist = NIL;*/
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joinrel->pathlist = NIL;
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joinrel->cheapestpath = (Path *) NULL;
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joinrel->pruneable = true;
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joinrel->classlist = NULL;
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joinrel->relam = InvalidOid;
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joinrel->ordering = NULL;
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joinrel->restrictinfo = NIL;
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joinrel->joininfo = NULL;
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joinrel->innerjoin = NIL;
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joinrel->superrels = NIL;
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joinrel->relids = lcons(outer_rel->relids, /* ??? aren't they lists?
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* -ay */
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lcons(inner_rel->relids, NIL));
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new_outer_tlist = nconc(new_outer_tlist, new_inner_tlist);
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joinrel->targetlist = new_outer_tlist;
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if (joininfo)
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{
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joinrel->restrictinfo = joininfo->jinfo_restrictinfo;
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if (BushyPlanFlag)
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joininfo->inactive = true;
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}
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joinrel_joininfo_list = new_joininfo_list(append(outer_rel->joininfo, inner_rel->joininfo),
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intAppend(outer_rel->relids, inner_rel->relids));
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joinrel->joininfo = joinrel_joininfo_list;
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set_joinrel_size(joinrel, outer_rel, inner_rel, joininfo);
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return joinrel;
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}
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/*
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* new_join_tlist
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* Builds a join relations's target list by keeping those elements that
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* will be in the final target list and any other elements that are still
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* needed for future joins. For a target list entry to still be needed
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* for future joins, its 'joinlist' field must not be empty after removal
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* of all relids in 'other_relids'.
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*
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* 'tlist' is the target list of one of the join relations
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* 'other_relids' is a list of relids contained within the other
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* join relation
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* 'first_resdomno' is the resdom number to use for the first created
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* target list entry
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*
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* Returns the new target list.
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*/
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static List *
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new_join_tlist(List *tlist,
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List *other_relids,
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int first_resdomno)
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{
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int resdomno = first_resdomno - 1;
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TargetEntry *xtl = NULL;
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List *temp_node = NIL;
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List *t_list = NIL;
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List *i = NIL;
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List *join_list = NIL;
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bool in_final_tlist = false;
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foreach(i, tlist)
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{
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xtl = lfirst(i);
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in_final_tlist = (join_list == NIL);
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if (in_final_tlist)
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{
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resdomno += 1;
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temp_node = lcons(create_tl_element(get_expr(xtl),
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resdomno),
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NIL);
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t_list = nconc(t_list, temp_node);
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}
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}
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return t_list;
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}
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/*
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* new_joininfo_list
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* Builds a join relation's joininfo list by checking for join clauses
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* which still need to used in future joins involving this relation. A
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* join clause is still needed if there are still relations in the clause
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* not contained in the list of relations comprising this join relation.
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* New joininfo nodes are only created and added to
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* 'current_joininfo_list' if a node for a particular join hasn't already
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* been created.
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*
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* 'current_joininfo_list' contains a list of those joininfo nodes that
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* have already been built
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* 'joininfo_list' is the list of join clauses involving this relation
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* 'join_relids' is a list of relids corresponding to the relations
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* currently being joined
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*
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* Returns a list of joininfo nodes, new and old.
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*/
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static List *
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new_joininfo_list(List *joininfo_list, List *join_relids)
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{
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List *current_joininfo_list = NIL;
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List *new_otherrels = NIL;
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JoinInfo *other_joininfo = (JoinInfo *) NULL;
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List *xjoininfo = NIL;
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foreach(xjoininfo, joininfo_list)
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{
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List *or;
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JoinInfo *joininfo = (JoinInfo *) lfirst(xjoininfo);
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new_otherrels = joininfo->otherrels;
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foreach(or, new_otherrels)
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{
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if (intMember(lfirsti(or), join_relids))
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new_otherrels = lremove((void *) lfirst(or), new_otherrels);
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}
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joininfo->otherrels = new_otherrels;
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if (new_otherrels != NIL)
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{
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other_joininfo = joininfo_member(new_otherrels,
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current_joininfo_list);
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if (other_joininfo)
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{
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other_joininfo->jinfo_restrictinfo = (List *) LispUnion(joininfo->jinfo_restrictinfo,
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other_joininfo->jinfo_restrictinfo);
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}
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else
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{
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other_joininfo = makeNode(JoinInfo);
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other_joininfo->otherrels = joininfo->otherrels;
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other_joininfo->jinfo_restrictinfo = joininfo->jinfo_restrictinfo;
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other_joininfo->mergejoinable = joininfo->mergejoinable;
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other_joininfo->hashjoinable = joininfo->hashjoinable;
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other_joininfo->inactive = false;
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current_joininfo_list = lcons(other_joininfo,
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current_joininfo_list);
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}
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}
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}
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return current_joininfo_list;
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}
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/*
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* add_new_joininfos
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* For each new join relation, create new joininfos that
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* use the join relation as inner relation, and add
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* the new joininfos to those rel nodes that still
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* have joins with the join relation.
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*
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* 'joinrels' is a list of join relations.
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*
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* Modifies the joininfo field of appropriate rel nodes.
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*/
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void
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add_new_joininfos(Query *root, List *joinrels, List *outerrels)
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{
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List *xjoinrel = NIL;
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List *xrelid = NIL;
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List *xrel = NIL;
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List *xjoininfo = NIL;
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foreach(xjoinrel, joinrels)
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{
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RelOptInfo *joinrel = (RelOptInfo *) lfirst(xjoinrel);
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foreach(xrelid, joinrel->relids)
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{
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Relid relid = (Relid) lfirst(xrelid);
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RelOptInfo *rel = get_join_rel(root, relid);
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add_superrels(rel, joinrel);
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}
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}
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foreach(xjoinrel, joinrels)
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{
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RelOptInfo *joinrel = (RelOptInfo *) lfirst(xjoinrel);
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foreach(xjoininfo, joinrel->joininfo)
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{
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JoinInfo *joininfo = (JoinInfo *) lfirst(xjoininfo);
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List *other_rels = joininfo->otherrels;
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List *restrict_info = joininfo->jinfo_restrictinfo;
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bool mergejoinable = joininfo->mergejoinable;
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bool hashjoinable = joininfo->hashjoinable;
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foreach(xrelid, other_rels)
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{
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Relid relid = (Relid) lfirst(xrelid);
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RelOptInfo *rel = get_join_rel(root, relid);
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List *super_rels = rel->superrels;
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List *xsuper_rel = NIL;
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JoinInfo *new_joininfo = makeNode(JoinInfo);
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new_joininfo->otherrels = joinrel->relids;
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new_joininfo->jinfo_restrictinfo = restrict_info;
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new_joininfo->mergejoinable = mergejoinable;
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new_joininfo->hashjoinable = hashjoinable;
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new_joininfo->inactive = false;
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rel->joininfo = lappend(rel->joininfo, new_joininfo);
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foreach(xsuper_rel, super_rels)
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{
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RelOptInfo *super_rel = (RelOptInfo *) lfirst(xsuper_rel);
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if (nonoverlap_rels(super_rel, joinrel))
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{
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List *new_relids = super_rel->relids;
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JoinInfo *other_joininfo = joininfo_member(new_relids,
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joinrel->joininfo);
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if (other_joininfo)
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{
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other_joininfo->jinfo_restrictinfo = (List *) LispUnion(restrict_info,
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other_joininfo->jinfo_restrictinfo);
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}
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else
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{
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JoinInfo *new_joininfo = makeNode(JoinInfo);
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new_joininfo->otherrels = new_relids;
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new_joininfo->jinfo_restrictinfo = restrict_info;
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new_joininfo->mergejoinable = mergejoinable;
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new_joininfo->hashjoinable = hashjoinable;
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new_joininfo->inactive = false;
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joinrel->joininfo = lappend(joinrel->joininfo,
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new_joininfo);
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}
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}
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}
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}
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}
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}
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foreach(xrel, outerrels)
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{
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RelOptInfo *rel = (RelOptInfo *) lfirst(xrel);
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rel->superrels = NIL;
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}
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}
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/*
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* final_join_rels
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* Find the join relation that includes all the original
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* relations, i.e. the final join result.
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*
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* 'join_rel_list' is a list of join relations.
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*
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* Returns the list of final join relations.
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*/
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List *
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final_join_rels(List *join_rel_list)
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{
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List *xrel = NIL;
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List *temp = NIL;
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List *t_list = NIL;
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/*
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* find the relations that has no further joins, i.e., its joininfos
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* all have otherrels nil.
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*/
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foreach(xrel, join_rel_list)
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{
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RelOptInfo *rel = (RelOptInfo *) lfirst(xrel);
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List *xjoininfo = NIL;
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bool final = true;
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foreach(xjoininfo, rel->joininfo)
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{
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JoinInfo *joininfo = (JoinInfo *) lfirst(xjoininfo);
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if (joininfo->otherrels != NIL)
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{
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final = false;
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break;
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}
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}
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if (final)
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{
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temp = lcons(rel, NIL);
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t_list = nconc(t_list, temp);
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}
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}
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return t_list;
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}
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/*
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* add_superrels
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* add rel to the temporary property list superrels.
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*
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* 'rel' a rel node
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* 'super_rel' rel node of a join relation that includes rel
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*
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* Modifies the superrels field of rel
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*/
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static void
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add_superrels(RelOptInfo *rel, RelOptInfo *super_rel)
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{
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rel->superrels = lappend(rel->superrels, super_rel);
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|
}
|
|
|
|
/*
|
|
* nonoverlap_rels
|
|
* test if two join relations overlap, i.e., includes the same
|
|
* relation.
|
|
*
|
|
* 'rel1' and 'rel2' are two join relations
|
|
*
|
|
* Returns non-nil if rel1 and rel2 do not overlap.
|
|
*/
|
|
static bool
|
|
nonoverlap_rels(RelOptInfo *rel1, RelOptInfo *rel2)
|
|
{
|
|
return nonoverlap_sets(rel1->relids, rel2->relids);
|
|
}
|
|
|
|
static bool
|
|
nonoverlap_sets(List *s1, List *s2)
|
|
{
|
|
List *x = NIL;
|
|
|
|
foreach(x, s1)
|
|
{
|
|
int e = lfirsti(x);
|
|
|
|
if (intMember(e, s2))
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static void
|
|
set_joinrel_size(RelOptInfo *joinrel, RelOptInfo *outer_rel, RelOptInfo *inner_rel, JoinInfo * jinfo)
|
|
{
|
|
int ntuples;
|
|
float selec;
|
|
|
|
/*
|
|
* voodoo magic. but better than a size of 0. I have no idea why we
|
|
* didn't set the size before. -ay 2/95
|
|
*/
|
|
if (jinfo == NULL)
|
|
{
|
|
/* worst case: the cartesian product */
|
|
ntuples = outer_rel->tuples * inner_rel->tuples;
|
|
}
|
|
else
|
|
{
|
|
selec = product_selec(jinfo->jinfo_restrictinfo);
|
|
/* ntuples = Min(outer_rel->tuples,inner_rel->tuples) * selec; */
|
|
ntuples = outer_rel->tuples * inner_rel->tuples * selec;
|
|
}
|
|
|
|
/*
|
|
* I bet sizes less than 1 will screw up optimization so make the best
|
|
* case 1 instead of 0 - jolly
|
|
*/
|
|
if (ntuples < 1)
|
|
ntuples = 1;
|
|
|
|
joinrel->tuples = ntuples;
|
|
}
|