storage/myisam/mi_delete.c

/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   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, version 2.0, 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/* Remove a row from a MyISAM table */

#include "fulltext.h"
#include "rt_index.h"

static int d_search(MI_INFO *info,MI_KEYDEF *keyinfo,uint comp_flag,
                    uchar *key,uint key_length,my_off_t page,uchar *anc_buff);
static int del(MI_INFO *info,MI_KEYDEF *keyinfo,uchar *key,uchar *anc_buff,
	       my_off_t leaf_page,uchar *leaf_buff,uchar *keypos,
	       my_off_t next_block,uchar *ret_key);
static int underflow(MI_INFO *info,MI_KEYDEF *keyinfo,uchar *anc_buff,
		     my_off_t leaf_page,uchar *leaf_buff,uchar *keypos);
static uint remove_key(MI_KEYDEF *keyinfo,uint nod_flag,uchar *keypos,
		       uchar *lastkey,uchar *page_end,
		       my_off_t *next_block);
static int _mi_ck_real_delete(register MI_INFO *info,MI_KEYDEF *keyinfo,
			      uchar *key, uint key_length, my_off_t *root);


int mi_delete(MI_INFO *info,const uchar *record)
{
  uint i;
  uchar *old_key;
  int save_errno;
  char lastpos[8];

  MYISAM_SHARE *share=info->s;
  DBUG_ENTER("mi_delete");

	/* Test if record is in datafile */

  DBUG_EXECUTE_IF("myisam_pretend_crashed_table_on_usage",
                  mi_print_error(info->s, HA_ERR_CRASHED);
                  DBUG_RETURN(my_errno= HA_ERR_CRASHED););
  DBUG_EXECUTE_IF("my_error_test_undefined_error",
                  mi_print_error(info->s, INT_MAX);
                  DBUG_RETURN(my_errno= INT_MAX););
  if (!(info->update & HA_STATE_AKTIV))
  {
    DBUG_RETURN(my_errno=HA_ERR_KEY_NOT_FOUND);	/* No database read */
  }
  if (share->options & HA_OPTION_READ_ONLY_DATA)
  {
    DBUG_RETURN(my_errno=EACCES);
  }
  if (_mi_readinfo(info,F_WRLCK,1))
    DBUG_RETURN(my_errno);
  if (info->s->calc_checksum)
    info->checksum=(*info->s->calc_checksum)(info,record);
  if ((*share->compare_record)(info,record))
    goto err;				/* Error on read-check */

  if (_mi_mark_file_changed(info))
    goto err;

	/* Remove all keys from the .ISAM file */

  old_key=info->lastkey2;
  for (i=0 ; i < share->base.keys ; i++ )
  {
    if (mi_is_key_active(info->s->state.key_map, i))
    {
      info->s->keyinfo[i].version++;
      if (info->s->keyinfo[i].flag & HA_FULLTEXT )
      {
        if (_mi_ft_del(info,i, old_key,record,info->lastpos))
          goto err;
      }
      else
      {
        if (info->s->keyinfo[i].ck_delete(info,i,old_key,
                _mi_make_key(info,i,old_key,record,info->lastpos)))
          goto err;
      }
    }
  }

  if ((*share->delete_record)(info))
    goto err;				/* Remove record from database */
  info->state->checksum-=info->checksum;

  info->update= HA_STATE_CHANGED+HA_STATE_DELETED+HA_STATE_ROW_CHANGED;
  info->state->records--;

  mi_sizestore(lastpos,info->lastpos);
  myisam_log_command(MI_LOG_DELETE,info,(uchar*) lastpos,sizeof(lastpos),0);
  (void) _mi_writeinfo(info,WRITEINFO_UPDATE_KEYFILE);

  if (info->invalidator != 0)
  {
    DBUG_PRINT("info", ("invalidator... '%s' (delete)", info->filename));
    (*info->invalidator)(info->filename);
    info->invalidator=0;
  }
  DBUG_RETURN(0);

err:
  save_errno=my_errno;
  mi_sizestore(lastpos,info->lastpos);
  myisam_log_command(MI_LOG_DELETE,info,(uchar*) lastpos, sizeof(lastpos),0);
  if (save_errno != HA_ERR_RECORD_CHANGED)
  {
    mi_print_error(info->s, HA_ERR_CRASHED);
    mi_mark_crashed(info);		/* mark table crashed */
  }
  (void) _mi_writeinfo(info,WRITEINFO_UPDATE_KEYFILE);
  info->update|=HA_STATE_WRITTEN;	/* Buffer changed */
  my_errno=save_errno;
  if (save_errno == HA_ERR_KEY_NOT_FOUND)
  {
    mi_print_error(info->s, HA_ERR_CRASHED);
    my_errno=HA_ERR_CRASHED;
  }

  DBUG_RETURN(my_errno);
} /* mi_delete */


	/* Remove a key from the btree index */

int _mi_ck_delete(register MI_INFO *info, uint keynr, uchar *key,
		  uint key_length)
{
  return _mi_ck_real_delete(info, info->s->keyinfo+keynr, key, key_length,
                            &info->s->state.key_root[keynr]);
} /* _mi_ck_delete */


static int _mi_ck_real_delete(register MI_INFO *info, MI_KEYDEF *keyinfo,
			      uchar *key, uint key_length, my_off_t *root)
{
  int error;
  uint nod_flag;
  my_off_t old_root;
  uchar *root_buff;
  DBUG_ENTER("_mi_ck_real_delete");

  if ((old_root=*root) == HA_OFFSET_ERROR)
  {
    mi_print_error(info->s, HA_ERR_CRASHED);
    DBUG_RETURN(my_errno=HA_ERR_CRASHED);
  }
  if (!(root_buff= (uchar*) my_alloca((uint) keyinfo->block_length+
				      MI_MAX_KEY_BUFF*2)))
  {
    DBUG_PRINT("error",("Couldn't allocate memory"));
    DBUG_RETURN(my_errno=ENOMEM);
  }
  DBUG_PRINT("info",("root_page: %ld", (long) old_root));
  if (!_mi_fetch_keypage(info,keyinfo,old_root,DFLT_INIT_HITS,root_buff,0))
  {
    error= -1;
    goto err;
  }
  if ((error=d_search(info,keyinfo,
                      (keyinfo->flag & HA_FULLTEXT ? SEARCH_FIND | SEARCH_UPDATE
                                                   : SEARCH_SAME),
                       key,key_length,old_root,root_buff)) >0)
  {
    if (error == 2)
    {
      DBUG_PRINT("test",("Enlarging of root when deleting"));
      error=_mi_enlarge_root(info,keyinfo,key,root);
    }
    else /* error == 1 */
    {
      if (mi_getint(root_buff) <= (nod_flag=mi_test_if_nod(root_buff))+3)
      {
	error=0;
	if (nod_flag)
	  *root=_mi_kpos(nod_flag,root_buff+2+nod_flag);
	else
	  *root=HA_OFFSET_ERROR;
	if (_mi_dispose(info,keyinfo,old_root,DFLT_INIT_HITS))
	  error= -1;
      }
      else
	error=_mi_write_keypage(info,keyinfo,old_root,
                                DFLT_INIT_HITS,root_buff);
    }
  }
err:
  my_afree((uchar*) root_buff);
  DBUG_PRINT("exit",("Return: %d",error));
  DBUG_RETURN(error);
} /* _mi_ck_real_delete */


	/*
	** Remove key below key root
	** Return values:
	** 1 if there are less buffers;  In this case anc_buff is not saved
	** 2 if there are more buffers
	** -1 on errors
	*/

static int d_search(register MI_INFO *info, register MI_KEYDEF *keyinfo,
                    uint comp_flag, uchar *key, uint key_length,
                    my_off_t page, uchar *anc_buff)
{
  int flag,ret_value,save_flag;
  uint length,nod_flag,search_key_length;
  my_bool last_key;
  uchar *leaf_buff,*keypos;
  my_off_t UNINIT_VAR(leaf_page),next_block;
  uchar lastkey[MI_MAX_KEY_BUFF];
  DBUG_ENTER("d_search");
  DBUG_DUMP("page",(uchar*) anc_buff,mi_getint(anc_buff));

  search_key_length= (comp_flag & SEARCH_FIND) ? key_length : USE_WHOLE_KEY;
  flag=(*keyinfo->bin_search)(info,keyinfo,anc_buff,key, search_key_length,
                              comp_flag, &keypos, lastkey, &last_key);
  if (flag == MI_FOUND_WRONG_KEY)
  {
    DBUG_PRINT("error",("Found wrong key"));
    DBUG_RETURN(-1);
  }
  nod_flag=mi_test_if_nod(anc_buff);

  if (!flag && keyinfo->flag & HA_FULLTEXT)
  {
    uint off;
    int  subkeys;

    get_key_full_length_rdonly(off, lastkey);
    subkeys=ft_sintXkorr(lastkey+off);
    DBUG_ASSERT(info->ft1_to_ft2==0 || subkeys >=0);
    comp_flag=SEARCH_SAME;
    if (subkeys >= 0)
    {
      /* normal word, one-level tree structure */
      if (info->ft1_to_ft2)
      {
        /* we're in ft1->ft2 conversion mode. Saving key data */
        if (insert_dynamic(info->ft1_to_ft2, (lastkey+off)))
        {
          DBUG_PRINT("error",("Out of memory"));
          DBUG_RETURN(-1);
        }
      }
      else
      {
        /* we need exact match only if not in ft1->ft2 conversion mode */
        flag=(*keyinfo->bin_search)(info,keyinfo,anc_buff,key,USE_WHOLE_KEY,
                                    comp_flag, &keypos, lastkey, &last_key);
      }
      /* fall through to normal delete */
    }
    else
    {
      /* popular word. two-level tree. going down */
      uint tmp_key_length;
      my_off_t root;
      uchar *kpos=keypos;

      if (!(tmp_key_length=(*keyinfo->get_key)(keyinfo,nod_flag,&kpos,lastkey)))
      {
        mi_print_error(info->s, HA_ERR_CRASHED);
        my_errno= HA_ERR_CRASHED;
        DBUG_RETURN(-1);
      }
      root=_mi_dpos(info,nod_flag,kpos);
      if (subkeys == -1)
      {
        /* the last entry in sub-tree */
        if (_mi_dispose(info, keyinfo, root,DFLT_INIT_HITS))
          DBUG_RETURN(-1);
        /* fall through to normal delete */
      }
      else
      {
        keyinfo=&info->s->ft2_keyinfo;
        kpos-=keyinfo->keylength+nod_flag; /* we'll modify key entry 'in vivo' */
        get_key_full_length_rdonly(off, key);
        key+=off;
        ret_value=_mi_ck_real_delete(info, &info->s->ft2_keyinfo,
            key, HA_FT_WLEN, &root);
        _mi_dpointer(info, kpos+HA_FT_WLEN, root);
        subkeys++;
        ft_intXstore(kpos, subkeys);
        if (!ret_value)
          ret_value=_mi_write_keypage(info,keyinfo,page,
                                      DFLT_INIT_HITS,anc_buff);
        DBUG_PRINT("exit",("Return: %d",ret_value));
        DBUG_RETURN(ret_value);
      }
    }
  }
  leaf_buff=0;
  LINT_INIT(leaf_page);
  if (nod_flag)
  {
    leaf_page=_mi_kpos(nod_flag,keypos);
    if (!(leaf_buff= (uchar*) my_alloca((uint) keyinfo->block_length+
					MI_MAX_KEY_BUFF*2)))
    {
      DBUG_PRINT("error",("Couldn't allocate memory"));
      my_errno=ENOMEM;
      DBUG_PRINT("exit",("Return: %d",-1));
      DBUG_RETURN(-1);
    }
    if (!_mi_fetch_keypage(info,keyinfo,leaf_page,DFLT_INIT_HITS,leaf_buff,0))
      goto err;
  }

  if (flag != 0)
  {
    if (!nod_flag)
    {
      DBUG_PRINT("error",("Didn't find key"));
      mi_print_error(info->s, HA_ERR_CRASHED);
      my_errno=HA_ERR_CRASHED;		/* This should newer happend */
      goto err;
    }
    save_flag=0;
    ret_value=d_search(info,keyinfo,comp_flag,key,key_length,
                       leaf_page,leaf_buff);
  }
  else
  {						/* Found key */
    uint tmp;
    length=mi_getint(anc_buff);
    if (!(tmp= remove_key(keyinfo,nod_flag,keypos,lastkey,anc_buff+length,
                          &next_block)))
      goto err;

    length-= tmp;

    mi_putint(anc_buff,length,nod_flag);
    if (!nod_flag)
    {						/* On leaf page */
      if (_mi_write_keypage(info,keyinfo,page,DFLT_INIT_HITS,anc_buff))
      {
        DBUG_PRINT("exit",("Return: %d",-1));
	DBUG_RETURN(-1);
      }
      /* Page will be update later if we return 1 */
      DBUG_RETURN(MY_TEST(length <= (info->quick_mode ? MI_MIN_KEYBLOCK_LENGTH :
                                     (uint) keyinfo->underflow_block_length)));
    }
    save_flag=1;
    ret_value=del(info,keyinfo,key,anc_buff,leaf_page,leaf_buff,keypos,
		  next_block,lastkey);
  }
  if (ret_value >0)
  {
    save_flag=1;
    if (ret_value == 1)
      ret_value= underflow(info,keyinfo,anc_buff,leaf_page,leaf_buff,keypos);
    else
    {				/* This happens only with packed keys */
      DBUG_PRINT("test",("Enlarging of key when deleting"));
      if (!_mi_get_last_key(info,keyinfo,anc_buff,lastkey,keypos,&length))
      {
	goto err;
      }
      ret_value=_mi_insert(info,keyinfo,key,anc_buff,keypos,lastkey,
			   (uchar*) 0,(uchar*) 0,(my_off_t) 0,(my_bool) 0);
    }
  }
  if (ret_value == 0 && mi_getint(anc_buff) > keyinfo->block_length)
  {
    save_flag=1;
    ret_value=_mi_split_page(info,keyinfo,key,anc_buff,lastkey,0) | 2;
  }
  if (save_flag && ret_value != 1)
    ret_value|=_mi_write_keypage(info,keyinfo,page,DFLT_INIT_HITS,anc_buff);
  else
  {
    DBUG_DUMP("page",(uchar*) anc_buff,mi_getint(anc_buff));
  }
  my_afree((uchar*) leaf_buff);
  DBUG_PRINT("exit",("Return: %d",ret_value));
  DBUG_RETURN(ret_value);

err:
  my_afree((uchar*) leaf_buff);
  DBUG_PRINT("exit",("Error: %d",my_errno));
  DBUG_RETURN (-1);
} /* d_search */


	/* Remove a key that has a page-reference */

static int del(register MI_INFO *info, register MI_KEYDEF *keyinfo, uchar *key,
	       uchar *anc_buff, my_off_t leaf_page, uchar *leaf_buff,
	       uchar *keypos,		/* Pos to where deleted key was */
	       my_off_t next_block,
	       uchar *ret_key)		/* key before keypos in anc_buff */
{
  int ret_value,length;
  uint a_length,nod_flag,tmp;
  my_off_t next_page;
  uchar keybuff[MI_MAX_KEY_BUFF],*endpos,*next_buff,*key_start, *prev_key;
  MYISAM_SHARE *share=info->s;
  MI_KEY_PARAM s_temp;
  DBUG_ENTER("del");
  DBUG_PRINT("enter",("leaf_page: %ld  keypos: 0x%lx", (long) leaf_page,
		      (ulong) keypos));
  DBUG_DUMP("leaf_buff",(uchar*) leaf_buff,mi_getint(leaf_buff));

  endpos=leaf_buff+mi_getint(leaf_buff);
  if (!(key_start=_mi_get_last_key(info,keyinfo,leaf_buff,keybuff,endpos,
				   &tmp)))
    DBUG_RETURN(-1);

  if ((nod_flag=mi_test_if_nod(leaf_buff)))
  {
    next_page= _mi_kpos(nod_flag,endpos);
    if (!(next_buff= (uchar*) my_alloca((uint) keyinfo->block_length+
					MI_MAX_KEY_BUFF*2)))
      DBUG_RETURN(-1);
    if (!_mi_fetch_keypage(info,keyinfo,next_page,DFLT_INIT_HITS,next_buff,0))
      ret_value= -1;
    else
    {
      DBUG_DUMP("next_page",(uchar*) next_buff,mi_getint(next_buff));
      if ((ret_value=del(info,keyinfo,key,anc_buff,next_page,next_buff,
			 keypos,next_block,ret_key)) >0)
      {
	endpos=leaf_buff+mi_getint(leaf_buff);
	if (ret_value == 1)
	{
	  ret_value=underflow(info,keyinfo,leaf_buff,next_page,
			      next_buff,endpos);
	  if (ret_value == 0 && mi_getint(leaf_buff) > keyinfo->block_length)
	  {
	    ret_value=_mi_split_page(info,keyinfo,key,leaf_buff,ret_key,0) | 2;
	  }
	}
	else
	{
	  DBUG_PRINT("test",("Inserting of key when deleting"));
	  if (!_mi_get_last_key(info,keyinfo,leaf_buff,keybuff,endpos,
				&tmp))
	    goto err;
	  ret_value=_mi_insert(info,keyinfo,key,leaf_buff,endpos,keybuff,
			       (uchar*) 0,(uchar*) 0,(my_off_t) 0,0);
	}
      }
      if (_mi_write_keypage(info,keyinfo,leaf_page,DFLT_INIT_HITS,leaf_buff))
	goto err;
    }
    my_afree((uchar*) next_buff);
    DBUG_RETURN(ret_value);
  }

	/* Remove last key from leaf page */

  mi_putint(leaf_buff,key_start-leaf_buff,nod_flag);
  if (_mi_write_keypage(info,keyinfo,leaf_page,DFLT_INIT_HITS,leaf_buff))
    goto err;

	/* Place last key in ancestor page on deleted key position */

  a_length=mi_getint(anc_buff);
  endpos=anc_buff+a_length;
  if (keypos != anc_buff+2+share->base.key_reflength &&
      !_mi_get_last_key(info,keyinfo,anc_buff,ret_key,keypos,&tmp))
    goto err;
  prev_key=(keypos == anc_buff+2+share->base.key_reflength ?
	    0 : ret_key);
  length=(*keyinfo->pack_key)(keyinfo,share->base.key_reflength,
			      keypos == endpos ? (uchar*) 0 : keypos,
			      prev_key, prev_key,
			      keybuff,&s_temp);
  if (length > 0)
    bmove_upp((uchar*) endpos+length,(uchar*) endpos,(uint) (endpos-keypos));
  else
    bmove(keypos,keypos-length, (int) (endpos-keypos)+length);
  (*keyinfo->store_key)(keyinfo,keypos,&s_temp);
  /* Save pointer to next leaf */
  if (!(*keyinfo->get_key)(keyinfo,share->base.key_reflength,&keypos,ret_key))
    goto err;
  _mi_kpointer(info,keypos - share->base.key_reflength,next_block);
  mi_putint(anc_buff,a_length+length,share->base.key_reflength);

  DBUG_RETURN( mi_getint(leaf_buff) <=
	       (info->quick_mode ? MI_MIN_KEYBLOCK_LENGTH :
		(uint) keyinfo->underflow_block_length));
err:
  DBUG_RETURN(-1);
} /* del */


	/* Balances adjacent pages if underflow occours */

static int underflow(register MI_INFO *info, register MI_KEYDEF *keyinfo,
		     uchar *anc_buff,
		     my_off_t leaf_page,/* Ancestor page and underflow page */
		     uchar *leaf_buff,
		     uchar *keypos)	/* Position to pos after key */
{
  int t_length;
  uint length,anc_length,buff_length,leaf_length,p_length,s_length,nod_flag,
       key_reflength,key_length;
  my_off_t next_page;
  uchar anc_key[MI_MAX_KEY_BUFF],leaf_key[MI_MAX_KEY_BUFF],
        *buff,*endpos,*next_keypos,*anc_pos,*half_pos,*temp_pos,*prev_key,
        *after_key;
  MI_KEY_PARAM s_temp;
  MYISAM_SHARE *share=info->s;
  DBUG_ENTER("underflow");
  DBUG_PRINT("enter",("leaf_page: %ld  keypos: 0x%lx",(long) leaf_page,
		      (ulong) keypos));
  DBUG_DUMP("anc_buff",(uchar*) anc_buff,mi_getint(anc_buff));
  DBUG_DUMP("leaf_buff",(uchar*) leaf_buff,mi_getint(leaf_buff));

  buff=info->buff;
  info->buff_used=1;
  next_keypos=keypos;
  nod_flag=mi_test_if_nod(leaf_buff);
  p_length=nod_flag+2;
  anc_length=mi_getint(anc_buff);
  leaf_length=mi_getint(leaf_buff);
  key_reflength=share->base.key_reflength;
  if (info->s->keyinfo+info->lastinx == keyinfo)
    info->page_changed=1;

  if ((keypos < anc_buff+anc_length && (info->state->records & 1)) ||
      keypos == anc_buff+2+key_reflength)
  {					/* Use page right of anc-page */
    DBUG_PRINT("test",("use right page"));

    if (keyinfo->flag & HA_BINARY_PACK_KEY)
    {
      if (!(next_keypos=_mi_get_key(info, keyinfo,
				    anc_buff, buff, keypos, &length)))
	goto err;
    }
    else
    {
      /* Got to end of found key */
      buff[0]=buff[1]=0;	/* Avoid length error check if packed key */
      if (!(*keyinfo->get_key)(keyinfo,key_reflength,&next_keypos,
			       buff))
      goto err;
    }
    next_page= _mi_kpos(key_reflength,next_keypos);
    if (!_mi_fetch_keypage(info,keyinfo,next_page,DFLT_INIT_HITS,buff,0))
      goto err;
    buff_length=mi_getint(buff);
    DBUG_DUMP("next",(uchar*) buff,buff_length);

    /* find keys to make a big key-page */
    bmove((uchar*) next_keypos-key_reflength,(uchar*) buff+2,
	  key_reflength);
    if (!_mi_get_last_key(info,keyinfo,anc_buff,anc_key,next_keypos,&length)
	|| !_mi_get_last_key(info,keyinfo,leaf_buff,leaf_key,
			     leaf_buff+leaf_length,&length))
      goto err;

    /* merge pages and put parting key from anc_buff between */
    prev_key=(leaf_length == p_length ? (uchar*) 0 : leaf_key);
    t_length=(*keyinfo->pack_key)(keyinfo,nod_flag,buff+p_length,
				  prev_key, prev_key,
				  anc_key, &s_temp);
    length=buff_length-p_length;
    endpos=buff+length+leaf_length+t_length;
    /* buff will always be larger than before !*/
    bmove_upp((uchar*) endpos, (uchar*) buff+buff_length,length);
    memcpy((uchar*) buff, (uchar*) leaf_buff,(size_t) leaf_length);
    (*keyinfo->store_key)(keyinfo,buff+leaf_length,&s_temp);
    buff_length=(uint) (endpos-buff);
    mi_putint(buff,buff_length,nod_flag);

    /* remove key from anc_buff */

    if (!(s_length=remove_key(keyinfo,key_reflength,keypos,anc_key,
                              anc_buff+anc_length,(my_off_t *) 0)))
      goto err;

    anc_length-=s_length;
    mi_putint(anc_buff,anc_length,key_reflength);

    if (buff_length <= keyinfo->block_length)
    {						/* Keys in one page */
      memcpy((uchar*) leaf_buff,(uchar*) buff,(size_t) buff_length);
      if (_mi_dispose(info,keyinfo,next_page,DFLT_INIT_HITS))
       goto err;
    }
    else
    {						/* Page is full */
      endpos=anc_buff+anc_length;
      DBUG_PRINT("test",("anc_buff: 0x%lx  endpos: 0x%lx",
                         (long) anc_buff, (long) endpos));
      if (keypos != anc_buff+2+key_reflength &&
	  !_mi_get_last_key(info,keyinfo,anc_buff,anc_key,keypos,&length))
	goto err;
      if (!(half_pos=_mi_find_half_pos(nod_flag, keyinfo, buff, leaf_key,
				       &key_length, &after_key)))
	goto err;
      length=(uint) (half_pos-buff);
      memcpy((uchar*) leaf_buff,(uchar*) buff,(size_t) length);
      mi_putint(leaf_buff,length,nod_flag);

      /* Correct new keypointer to leaf_page */
      half_pos=after_key;
      _mi_kpointer(info,leaf_key+key_length,next_page);
      /* Save key in anc_buff */
      prev_key=(keypos == anc_buff+2+key_reflength ? (uchar*) 0 : anc_key),
      t_length=(*keyinfo->pack_key)(keyinfo,key_reflength,
				    (keypos == endpos ? (uchar*) 0 :
				     keypos),
				    prev_key, prev_key,
				    leaf_key, &s_temp);
      if (t_length >= 0)
	bmove_upp((uchar*) endpos+t_length,(uchar*) endpos,
		  (uint) (endpos-keypos));
      else
	bmove(keypos,keypos-t_length,(uint) (endpos-keypos)+t_length);
      (*keyinfo->store_key)(keyinfo,keypos,&s_temp);
      mi_putint(anc_buff,(anc_length+=t_length),key_reflength);

	/* Store key first in new page */
      if (nod_flag)
	bmove((uchar*) buff+2,(uchar*) half_pos-nod_flag,(size_t) nod_flag);
      if (!(*keyinfo->get_key)(keyinfo,nod_flag,&half_pos,leaf_key))
	goto err;
      t_length=(int) (*keyinfo->pack_key)(keyinfo, nod_flag, (uchar*) 0,
					  (uchar*) 0, (uchar *) 0,
					  leaf_key, &s_temp);
      /* t_length will always be > 0 for a new page !*/
      length=(uint) ((buff+mi_getint(buff))-half_pos);
      bmove((uchar*) buff+p_length+t_length,(uchar*) half_pos,(size_t) length);
      (*keyinfo->store_key)(keyinfo,buff+p_length,&s_temp);
      mi_putint(buff,length+t_length+p_length,nod_flag);

      if (_mi_write_keypage(info,keyinfo,next_page,DFLT_INIT_HITS,buff))
	goto err;
    }
    if (_mi_write_keypage(info,keyinfo,leaf_page,DFLT_INIT_HITS,leaf_buff))
      goto err;
    DBUG_RETURN(anc_length <= ((info->quick_mode ? MI_MIN_BLOCK_LENGTH :
				(uint) keyinfo->underflow_block_length)));
  }

  DBUG_PRINT("test",("use left page"));

  keypos=_mi_get_last_key(info,keyinfo,anc_buff,anc_key,keypos,&length);
  if (!keypos)
    goto err;
  next_page= _mi_kpos(key_reflength,keypos);
  if (!_mi_fetch_keypage(info,keyinfo,next_page,DFLT_INIT_HITS,buff,0))
      goto err;
  buff_length=mi_getint(buff);
  endpos=buff+buff_length;
  DBUG_DUMP("prev",(uchar*) buff,buff_length);

  /* find keys to make a big key-page */
  bmove((uchar*) next_keypos - key_reflength,(uchar*) leaf_buff+2,
	key_reflength);
  next_keypos=keypos;
  if (!(*keyinfo->get_key)(keyinfo,key_reflength,&next_keypos,
			   anc_key))
    goto err;
  if (!_mi_get_last_key(info,keyinfo,buff,leaf_key,endpos,&length))
    goto err;

  /* merge pages and put parting key from anc_buff between */
  prev_key=(leaf_length == p_length ? (uchar*) 0 : leaf_key);
  t_length=(*keyinfo->pack_key)(keyinfo,nod_flag,
				(leaf_length == p_length ?
                                 (uchar*) 0 : leaf_buff+p_length),
				prev_key, prev_key,
				anc_key, &s_temp);
  if (t_length >= 0)
    bmove((uchar*) endpos+t_length,(uchar*) leaf_buff+p_length,
	    (size_t) (leaf_length-p_length));
  else						/* We gained space */
    bmove((uchar*) endpos,(uchar*) leaf_buff+((int) p_length-t_length),
	  (size_t) (leaf_length-p_length+t_length));

  (*keyinfo->store_key)(keyinfo,endpos,&s_temp);
  buff_length=buff_length+leaf_length-p_length+t_length;
  mi_putint(buff,buff_length,nod_flag);

  /* remove key from anc_buff */
  if (!(s_length= remove_key(keyinfo,key_reflength,keypos,anc_key,
                             anc_buff+anc_length,(my_off_t *) 0)))
    goto err;

  anc_length-=s_length;
  mi_putint(anc_buff,anc_length,key_reflength);

  if (buff_length <= keyinfo->block_length)
  {						/* Keys in one page */
    if (_mi_dispose(info,keyinfo,leaf_page,DFLT_INIT_HITS))
      goto err;
  }
  else
  {						/* Page is full */
    if (keypos == anc_buff+2+key_reflength)
      anc_pos=0;				/* First key */
    else if (!_mi_get_last_key(info,keyinfo,anc_buff,anc_pos=anc_key,keypos,
			       &length))
      goto err;
    endpos=_mi_find_half_pos(nod_flag,keyinfo,buff,leaf_key,
			     &key_length, &half_pos);
    if (!endpos)
      goto err;
    _mi_kpointer(info,leaf_key+key_length,leaf_page);
    /* Save key in anc_buff */
    DBUG_DUMP("anc_buff",(uchar*) anc_buff,anc_length);
    DBUG_DUMP("key_to_anc",(uchar*) leaf_key,key_length);

    temp_pos=anc_buff+anc_length;
    t_length=(*keyinfo->pack_key)(keyinfo,key_reflength,
				  keypos == temp_pos ? (uchar*) 0
				  : keypos,
				  anc_pos, anc_pos,
				  leaf_key,&s_temp);
    if (t_length > 0)
      bmove_upp((uchar*) temp_pos+t_length,(uchar*) temp_pos,
		(uint) (temp_pos-keypos));
    else
      bmove(keypos,keypos-t_length,(uint) (temp_pos-keypos)+t_length);
    (*keyinfo->store_key)(keyinfo,keypos,&s_temp);
    mi_putint(anc_buff,(anc_length+=t_length),key_reflength);

    /* Store first key on new page */
    if (nod_flag)
      bmove((uchar*) leaf_buff+2,(uchar*) half_pos-nod_flag,(size_t) nod_flag);
    if (!(length=(*keyinfo->get_key)(keyinfo,nod_flag,&half_pos,leaf_key)))
      goto err;
    DBUG_DUMP("key_to_leaf",(uchar*) leaf_key,length);
    t_length=(*keyinfo->pack_key)(keyinfo,nod_flag, (uchar*) 0,
				  (uchar*) 0, (uchar*) 0, leaf_key, &s_temp);
    length=(uint) ((buff+buff_length)-half_pos);
    DBUG_PRINT("info",("t_length: %d  length: %d",t_length,(int) length));
    bmove((uchar*) leaf_buff+p_length+t_length,(uchar*) half_pos,
	  (size_t) length);
    (*keyinfo->store_key)(keyinfo,leaf_buff+p_length,&s_temp);
    mi_putint(leaf_buff,length+t_length+p_length,nod_flag);
    if (_mi_write_keypage(info,keyinfo,leaf_page,DFLT_INIT_HITS,leaf_buff))
      goto err;
    mi_putint(buff,endpos-buff,nod_flag);
  }
  if (_mi_write_keypage(info,keyinfo,next_page,DFLT_INIT_HITS,buff))
    goto err;
  DBUG_RETURN(anc_length <= (uint) keyinfo->block_length/2);

err:
  DBUG_RETURN(-1);
} /* underflow */


	/*
	  remove a key from packed buffert
	  The current code doesn't handle the case that the next key may be
	  packed better against the previous key if there is a case difference
	  returns how many chars was removed or 0 on error
	*/

static uint remove_key(MI_KEYDEF *keyinfo, uint nod_flag,
		       uchar *keypos,	/* Where key starts */
		       uchar *lastkey,	/* key to be removed */
		       uchar *page_end, /* End of page */
		       my_off_t *next_block)	/* ptr to next block */
{
  int s_length;
  uchar *start;
  DBUG_ENTER("remove_key");
  DBUG_PRINT("enter",("keypos: 0x%lx  page_end: 0x%lx",(long) keypos, (long) page_end));

  start=keypos;
  if (!(keyinfo->flag &
	(HA_PACK_KEY | HA_SPACE_PACK_USED | HA_VAR_LENGTH_KEY |
	 HA_BINARY_PACK_KEY)))
  {
    s_length=(int) (keyinfo->keylength+nod_flag);
    if (next_block && nod_flag)
      *next_block= _mi_kpos(nod_flag,keypos+s_length);
  }
  else
  {					 /* Let keypos point at next key */
    /* Calculate length of key */
    if (!(*keyinfo->get_key)(keyinfo,nod_flag,&keypos,lastkey))
      DBUG_RETURN(0);				/* Error */

    if (next_block && nod_flag)
      *next_block= _mi_kpos(nod_flag,keypos);
    s_length=(int) (keypos-start);
    if (keypos != page_end)
    {
      if (keyinfo->flag & HA_BINARY_PACK_KEY)
      {
	uchar *old_key=start;
	uint next_length,prev_length,prev_pack_length;
	get_key_length(next_length,keypos);
	get_key_pack_length(prev_length,prev_pack_length,old_key);
	if (next_length > prev_length)
	{
	  /* We have to copy data from the current key to the next key */
	  bmove_upp(keypos, (lastkey+next_length),
		    (next_length-prev_length));
	  keypos-=(next_length-prev_length)+prev_pack_length;
	  store_key_length(keypos,prev_length);
	  s_length=(int) (keypos-start);
	}
      }
      else
      {
	/* Check if a variable length first key part */
	if ((keyinfo->seg->flag & HA_PACK_KEY) && *keypos & 128)
	{
	  /* Next key is packed against the current one */
	  uint next_length,prev_length,prev_pack_length,lastkey_length,
	    rest_length;
	  if (keyinfo->seg[0].length >= 127)
	  {
	    if (!(prev_length=mi_uint2korr(start) & 32767))
	      goto end;
	    next_length=mi_uint2korr(keypos) & 32767;
	    keypos+=2;
	    prev_pack_length=2;
	  }
	  else
	  {
	    if (!(prev_length= *start & 127))
	      goto end;				/* Same key as previous*/
	    next_length= *keypos & 127;
	    keypos++;
	    prev_pack_length=1;
	  }
	  if (!(*start & 128))
	    prev_length=0;			/* prev key not packed */
	  if (keyinfo->seg[0].flag & HA_NULL_PART)
	    lastkey++;				/* Skip null marker */
	  get_key_length(lastkey_length,lastkey);
	  if (!next_length)			/* Same key after */
	  {
	    next_length=lastkey_length;
	    rest_length=0;
	  }
	  else
	    get_key_length(rest_length,keypos);

	  if (next_length >= prev_length)
	  {		/* Key after is based on deleted key */
	    uint pack_length,tmp;
	    bmove_upp(keypos, (lastkey+next_length),
		      tmp=(next_length-prev_length));
	    rest_length+=tmp;
	    pack_length= prev_length ? get_pack_length(rest_length): 0;
	    keypos-=tmp+pack_length+prev_pack_length;
	    s_length=(int) (keypos-start);
	    if (prev_length)			/* Pack against prev key */
	    {
	      *keypos++= start[0];
	      if (prev_pack_length == 2)
		*keypos++= start[1];
	      store_key_length(keypos,rest_length);
	    }
	    else
	    {
	      /* Next key is not packed anymore */
	      if (keyinfo->seg[0].flag & HA_NULL_PART)
	      {
		rest_length++;			/* Mark not null */
	      }
	      if (prev_pack_length == 2)
	      {
		mi_int2store(keypos,rest_length);
	      }
	      else
		*keypos= rest_length;
	    }
	  }
	}
      }
    }
  }
  end:
  bmove((uchar*) start,(uchar*) start+s_length,
	(uint) (page_end-start-s_length));
  DBUG_RETURN((uint) s_length);
} /* remove_key */