mariadb/myisam/rt_key.c

/* Copyright (C) 2000 MySQL AB & Ramil Kalimullin & MySQL Finland AB 
   & TCX DataKonsult AB
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include "myisamdef.h"

#include "rt_index.h"
#include "rt_key.h"
#include "rt_mbr.h"

/*
Add key to the page
Result values:
-1 - error
 0 - not split
 1 - split
*/
int rtree_add_key(MI_INFO *info, MI_KEYDEF *keyinfo, uchar *key, 
                 uint key_length, uchar *page_buf, my_off_t *new_page)
{
  uint page_size = mi_getint(page_buf);
  uint nod_flag = mi_test_if_nod(page_buf);

  if (page_size + key_length + nod_flag <= keyinfo->block_length)  
  {
    /* split won't be necessary */
    if (nod_flag)
    {
      /* save key */
      memcpy(rt_PAGE_END(page_buf), key - nod_flag, key_length + nod_flag); 
      page_size += key_length + nod_flag;
    }
    else
    {
      /* save key */
      memcpy(rt_PAGE_END(page_buf), key, key_length + 
                                         info->s->base.rec_reflength);
      page_size += key_length + info->s->base.rec_reflength;
    }
    mi_putint(page_buf, page_size, nod_flag);
    return 0;
  }
  else
  { 
    if (rtree_split_page(info, keyinfo, page_buf, key, key_length, new_page))
      return -1;
    else 
      return 1;
  }
}

/*
Delete key from the page
*/
int rtree_delete_key(MI_INFO *info, uchar *page_buf, uchar *key, 
                    uint key_length, uint nod_flag)
{
  uint16 page_size = mi_getint(page_buf);
  uchar *key_start;

  if (nod_flag)
  {
    key_start = key - nod_flag;
  }
  else
  {
    key_start = key;
    key_length += info->s->base.rec_reflength;
  }
  memmove(key_start, key + key_length, page_size - key_length - 
                                       (key - page_buf));
  page_size -= key_length + nod_flag;

  mi_putint(page_buf, page_size, nod_flag);

  return 0;
}

/*
Calculate and store key MBR
*/
int rtree_set_key_mbr(MI_INFO *info, MI_KEYDEF *keyinfo, uchar *key, 
                    uint key_length, my_off_t child_page)
{
  uchar *k;
  uchar *last;
  uint nod_flag;

  if (!_mi_fetch_keypage(info, keyinfo, child_page, info->buff, 0))
    goto err1;
  nod_flag = mi_test_if_nod(info->buff);

  k = rt_PAGE_FIRST_KEY(info->buff, nod_flag);
  last = rt_PAGE_END(info->buff);

  rtree_page_mbr(info, keyinfo->seg, info->buff, key, key_length);

  return 0;

err1:
  return -1;
}

/*
Choose non-leaf better key for insertion
*/
uchar *rtree_choose_key(MI_INFO *info, MI_KEYDEF *keyinfo, uchar *key, 
                       uint key_length, uchar *page_buf, uint nod_flag)
{
  double increase;
  double best_incr = DBL_MAX;
  double area;
  double best_area;
  uchar *best_key;

  uchar *k = rt_PAGE_FIRST_KEY(page_buf, nod_flag);
  uchar *last = rt_PAGE_END(page_buf);

  for (; k < last; k = rt_PAGE_NEXT_KEY(k, key_length, nod_flag))
  {
    if ((increase = rtree_area_increase(keyinfo->seg, key, k, key_length, 
                                        &area)) == -1)
      return NULL;
    if (increase < best_incr)
    {
      best_key = k;
      best_area = area;
      best_incr = increase;
    }
    else
    {
      if ((increase == best_incr) && (area < best_area))
      {
        best_key = k;
        best_area = area;
        best_incr = increase;
      }
    }
  }
  return best_key;
}