release/src/router/mysql/storage/myisammrg/myrg_queue.c

   1 /* Copyright (c) 2000-2003, 2005-2007 MySQL AB
   2
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; version 2 of the License.
   6
   7    This program is distributed in the hope that it will be useful,
   8    but WITHOUT ANY WARRANTY; without even the implied warranty of
   9    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10    GNU General Public License for more details.
  11
  12    You should have received a copy of the GNU General Public License
  13    along with this program; if not, write to the Free Software
  14    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA */
  15
  16 #include "myrg_def.h"
  17
  18 static int queue_key_cmp(void *keyseg, uchar *a, uchar *b)
  19 {
  20   MYRG_TABLE *ma= (MYRG_TABLE *)a;
  21   MYRG_TABLE *mb= (MYRG_TABLE *)b;
  22   MI_INFO *aa= ma->table;
  23   MI_INFO *bb= mb->table;
  24   uint not_used[2];
  25   int ret= ha_key_cmp((HA_KEYSEG *)keyseg, aa->lastkey, bb->lastkey,
  26                        USE_WHOLE_KEY, SEARCH_FIND, not_used);
  27   if (ret < 0)
  28     return -1;
  29   if (ret > 0)
  30     return 1;
  31
  32   /*
  33     If index tuples have the same values, let the record with least rowid
  34     value be "smaller", so index scans return records ordered by (keytuple,
  35     rowid). This is used by index_merge access method, grep for ROR in
  36     sql/opt_range.cc for details.
  37   */
  38   return (ma->file_offset < mb->file_offset)? -1 : (ma->file_offset >
  39                                                     mb->file_offset) ? 1 : 0;
  40 } /* queue_key_cmp */
  41
  42
  43 int _myrg_init_queue(MYRG_INFO *info,int inx,enum ha_rkey_function search_flag)
  44 {
  45   int error=0;
  46   QUEUE *q= &(info->by_key);
  47
  48   if (inx < (int) info->keys)
  49   {
  50     if (!is_queue_inited(q))
  51     {
  52       if (init_queue(q,info->tables, 0,
  53                      (myisam_readnext_vec[search_flag] == SEARCH_SMALLER),
  54                      queue_key_cmp,
  55                      info->open_tables->table->s->keyinfo[inx].seg))
  56         error=my_errno;
  57     }
  58     else
  59     {
  60       if (reinit_queue(q,info->tables, 0,
  61                        (myisam_readnext_vec[search_flag] == SEARCH_SMALLER),
  62                        queue_key_cmp,
  63                        info->open_tables->table->s->keyinfo[inx].seg))
  64         error=my_errno;
  65     }
  66   }
  67   else
  68     my_errno= error= HA_ERR_WRONG_INDEX;
  69   return error;
  70 }
  71
  72 int _myrg_mi_read_record(MI_INFO *info, uchar *buf)
  73 {
  74   if (!(*info->read_record)(info,info->lastpos,buf))
  75   {
  76     info->update|= HA_STATE_AKTIV;              /* Record is read */
  77     return 0;
  78   }
  79   return my_errno;
  80 }