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

   1 /*-------------------------------------------------------------------------
   2  *
   3  * relnode.c--
   4  *        Relation manipulation routines
   5  *
   6  * Copyright (c) 1994, Regents of the University of California
   7  *
   8  *
   9  * IDENTIFICATION
  10  *        $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.3 1997/09/08 02:25:02 momjian Exp $
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #include "postgres.h"
  15
  16 #include "nodes/relation.h"
  17
  18 #include "optimizer/internal.h"
  19 #include "optimizer/pathnode.h" /* where the decls go */
  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 Rel                *
  31 get_base_rel(Query * root, int relid)
  32 {
  33         List       *relids;
  34         Rel                *rel;
  35
  36         relids = lconsi(relid, NIL);
  37         rel = rel_member(relids, root->base_relation_list_);
  38         if (rel == NULL)
  39         {
  40                 rel = makeNode(Rel);
  41                 rel->relids = relids;
  42                 rel->indexed = false;
  43                 rel->pages = 0;
  44                 rel->tuples = 0;
  45                 rel->width = 0;
  46                 rel->targetlist = NIL;
  47                 rel->pathlist = NIL;
  48                 rel->unorderedpath = (Path *) NULL;
  49                 rel->cheapestpath = (Path *) NULL;
  50                 rel->pruneable = true;
  51                 rel->classlist = NULL;
  52                 rel->ordering = NULL;
  53                 rel->relam = InvalidOid;
  54                 rel->clauseinfo = NIL;
  55                 rel->joininfo = NIL;
  56                 rel->innerjoin = NIL;
  57                 rel->superrels = NIL;
  58
  59                 root->base_relation_list_ = lcons(rel,
  60                                                                                   root->base_relation_list_);
  61
  62                 /*
  63                  * ??? the old lispy C code (get_rel) do a listp(relid) here but
  64                  * that can never happen since we already established relid is not
  65                  * a list.                                                              -ay 10/94
  66                  */
  67                 if (relid < 0)
  68                 {
  69
  70                         /*
  71                          * If the relation is a materialized relation, assume
  72                          * constants for sizes.
  73                          */
  74                         rel->pages = _TEMP_RELATION_PAGES_;
  75                         rel->tuples = _TEMP_RELATION_TUPLES_;
  76
  77                 }
  78                 else
  79                 {
  80                         bool            hasindex;
  81                         int                     pages,
  82                                                 tuples;
  83
  84                         /*
  85                          * Otherwise, retrieve relation characteristics from the
  86                          * system catalogs.
  87                          */
  88                         relation_info(root, relid, &hasindex, &pages, &tuples);
  89                         rel->indexed = hasindex;
  90                         rel->pages = pages;
  91                         rel->tuples = tuples;
  92                 }
  93         }
  94         return rel;
  95 }
  96
  97 /*
  98  * get_join_rel--
  99  *        Returns relation entry corresponding to 'relid' (a list of relids),
 100  *        creating a new one if necessary. This is for join relations.
 101  *
 102  */
 103 Rel                *
 104 get_join_rel(Query * root, List * relid)
 105 {
 106         return rel_member(relid, root->join_relation_list_);
 107 }
 108
 109 /*
 110  * rel-member--
 111  *        Determines whether a relation of id 'relid' is contained within a list
 112  *        'rels'.
 113  *
 114  * Returns the corresponding entry in 'rels' if it is there.
 115  *
 116  */
 117 Rel                *
 118 rel_member(List * relid, List * rels)
 119 {
 120         List       *temp = NIL;
 121         List       *temprelid = NIL;
 122
 123         if (relid != NIL && rels != NIL)
 124         {
 125                 foreach(temp, rels)
 126                 {
 127                         temprelid = ((Rel *) lfirst(temp))->relids;
 128                         if (same(temprelid, relid))
 129                                 return ((Rel *) (lfirst(temp)));
 130                 }
 131         }
 132         return (NULL);
 133 }