Function create_ref_for_key

sql/sql_select.cc:13692–13920

}

static bool create_ref_for_key(JOIN *join, JOIN_TAB *j,
                               KEYUSE *org_keyuse, bool allow_full_scan, 
                               table_map used_tables)
{
  uint keyparts, length, key;
  TABLE *table;
  KEY *keyinfo;
  KEYUSE *keyuse= org_keyuse;
  bool ftkey= (keyuse->keypart == FT_KEYPART);
  THD *thd= join->thd;
  DBUG_ENTER("create_ref_for_key");

  /*  Use best key from find_best */
  table= j->table;
  key= keyuse->key;
  if (!is_hash_join_key_no(key))
    keyinfo= table->key_info+key;
  else
  {
    if (create_hj_key_for_table(join, j, org_keyuse, used_tables))
      DBUG_RETURN(TRUE);
    keyinfo= j->hj_key;
  }

  if (ftkey)
  {
    Item_func_match *ifm=(Item_func_match *)keyuse->val;

    length=0;
    keyparts=1;
    ifm->join_key=1;
  }
  else
  {
    keyparts=length=0;
    uint found_part_ref_or_null= 0;
    /*
      Calculate length for the used key
      Stop if there is a missing key part or when we find second key_part
      with KEY_OPTIMIZE_REF_OR_NULL
    */
    do
    {
      if (!(~used_tables & keyuse->used_tables) &&
          (!keyuse->validity_ref || *keyuse->validity_ref) &&
	  j->keyuse_is_valid_for_access_in_chosen_plan(join, keyuse))
      {
        if  (are_tables_local(j, keyuse->val->used_tables()))
        {
          if ((is_hash_join_key_no(key) && keyuse->keypart != NO_KEYPART) ||
              (!is_hash_join_key_no(key) && keyparts == keyuse->keypart &&
               !(found_part_ref_or_null & keyuse->optimize)))
          {
             length+= keyinfo->key_part[keyparts].store_length;
             keyparts++;
             found_part_ref_or_null|= keyuse->optimize & ~KEY_OPTIMIZE_EQ;
          }
        }