granicus.if.org Git - postgresql/blob - src/backend/optimizer/util/relnode.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * relnode.c
   4  *        Relation manipulation routines
   5  *
   6  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.21 2000/01/26 05:56:40 momjian Exp $
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17
  18 #include "optimizer/internal.h"
  19 #include "optimizer/pathnode.h"
  20 #include "optimizer/plancat.h"
  21
  22
  23
  24 /*
  25  * get_base_rel
  26  *        Returns relation entry corresponding to 'relid', creating a new one if
  27  *        necessary. This is for base relations.
  28  *
  29  */
  30 RelOptInfo *
  31 get_base_rel(Query *root, int relid)
  32 {
  33         Relids          relids = lconsi(relid, NIL);
  34         RelOptInfo *rel;
  35
  36         rel = rel_member(relids, root->base_rel_list);
  37         if (rel == NULL)
  38         {
  39                 rel = makeNode(RelOptInfo);
  40                 rel->relids = relids;
  41                 rel->rows = 0;
  42                 rel->width = 0;
  43                 rel->targetlist = NIL;
  44                 rel->pathlist = NIL;
  45                 rel->cheapestpath = (Path *) NULL;
  46                 rel->pruneable = true;
  47                 rel->indexed = false;
  48                 rel->pages = 0;
  49                 rel->tuples = 0;
  50                 rel->restrictinfo = NIL;
  51                 rel->joininfo = NIL;
  52                 rel->innerjoin = NIL;
  53
  54                 root->base_rel_list = lcons(rel, root->base_rel_list);
  55
  56                 if (relid < 0)
  57                 {
  58                         /*
  59                          * If the relation is a materialized relation, assume
  60                          * constants for sizes.
  61                          */
  62                         rel->pages = _NONAME_RELATION_PAGES_;
  63                         rel->tuples = _NONAME_RELATION_TUPLES_;
  64                 }
  65                 else
  66                 {
  67                         /*
  68                          * Otherwise, retrieve relation statistics from the
  69                          * system catalogs.
  70                          */
  71                         relation_info(root, relid,
  72                                                   &rel->indexed, &rel->pages, &rel->tuples);
  73                 }
  74         }
  75         return rel;
  76 }
  77
  78 /*
  79  * get_join_rel
  80  *        Returns relation entry corresponding to 'relid' (a list of relids),
  81  *        or NULL.
  82  */
  83 RelOptInfo *
  84 get_join_rel(Query *root, Relids relid)
  85 {
  86         return rel_member(relid, root->join_rel_list);
  87 }
  88
  89 /*
  90  * rel_member
  91  *        Determines whether a relation of id 'relid' is contained within a list
  92  *        'rels'.
  93  *
  94  * Returns the corresponding entry in 'rels' if it is there.
  95  *
  96  */
  97 RelOptInfo *
  98 rel_member(Relids relids, List *rels)
  99 {
 100         if (relids != NIL && rels != NIL)
 101         {
 102                 List       *temp;
 103
 104                 foreach(temp, rels)
 105                 {
 106                         RelOptInfo *rel = (RelOptInfo *) lfirst(temp);
 107
 108                         if (same(rel->relids, relids))
 109                                 return rel;
 110                 }
 111         }
 112         return NULL;
 113 }