hp_rfirst.c 2.34 KB
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/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
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   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.
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   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.
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   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 "heapdef.h"

/* Read first record with the current key */

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int heap_rfirst(HP_INFO *info, byte *record, int inx)
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{
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  HP_SHARE *share = info->s;
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  HP_KEYDEF *keyinfo = share->keydef + inx;
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  DBUG_ENTER("heap_rfirst");
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  info->lastinx= inx;
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  if (keyinfo->algorithm == HA_KEY_ALG_BTREE)
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  {
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    byte *pos;

    if ((pos = tree_search_edge(&keyinfo->rb_tree, info->parents,
                                &info->last_pos, offsetof(TREE_ELEMENT, left))))
    {
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      memcpy(&pos, pos + (*keyinfo->get_key_length)(keyinfo, pos), 
	     sizeof(byte*));
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      info->current_ptr = pos;
      memcpy(record, pos, (size_t)share->reclength);
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      /*
        If we're performing index_first on a table that was taken from
        table cache, info->lastkey_len is initialized to previous query.
        Thus we set info->lastkey_len to proper value for subsequent
        heap_rnext() calls.
        This is needed for DELETE queries only, otherwise this variable is
        not used.
        Note that the same workaround may be needed for heap_rlast(), but
        for now heap_rlast() is never used for DELETE queries.
      */
      info->lastkey_len= 0;
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      info->update = HA_STATE_AKTIV;
    }
    else
    {
      my_errno = HA_ERR_END_OF_FILE;
      DBUG_RETURN(my_errno);
    }
    DBUG_RETURN(0);
  }
  else
  {
    if (!(info->s->records))
    {
      my_errno=HA_ERR_END_OF_FILE;
      DBUG_RETURN(my_errno);
    }
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    DBUG_ASSERT(0); /* TODO fix it */
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    info->current_record=0;
    info->current_hash_ptr=0;
    info->update=HA_STATE_PREV_FOUND;
    DBUG_RETURN(heap_rnext(info,record));
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  }
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}