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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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Gives a approximated number of how many records there is between two keys.
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Used when optimizing querries.
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#include "myisam_priv.h"
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using namespace drizzled;
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static ha_rows _mi_record_pos(MI_INFO *, const unsigned char *, key_part_map,
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#include "myisamdef.h"
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static ha_rows _mi_record_pos(MI_INFO *, const uchar *, key_part_map,
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enum ha_rkey_function);
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static double _mi_search_pos(MI_INFO *,MI_KEYDEF *,unsigned char *, uint,uint,internal::my_off_t);
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static uint32_t _mi_keynr(MI_INFO *info,MI_KEYDEF *,unsigned char *, unsigned char *,uint32_t *);
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static double _mi_search_pos(MI_INFO *,MI_KEYDEF *,uchar *, uint,uint,my_off_t);
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static uint _mi_keynr(MI_INFO *info,MI_KEYDEF *,uchar *, uchar *,uint *);
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Estimate how many records there is in a given range
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HA_POS_ERROR error (or we can't estimate number of rows)
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number Estimated number of rows
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ha_rows mi_records_in_range(MI_INFO *info, int inx,
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key_range *min_key, key_range *max_key)
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ha_rows start_pos,end_pos,res;
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DBUG_ENTER("mi_records_in_range");
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if ((inx = _mi_check_index(info,inx)) < 0)
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DBUG_RETURN(HA_POS_ERROR);
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if (fast_mi_readinfo(info))
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DBUG_RETURN(HA_POS_ERROR);
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info->update&= (HA_STATE_CHANGED+HA_STATE_ROW_CHANGED);
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if (info->s->concurrent_insert)
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rw_rdlock(&info->s->key_root_lock[inx]);
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switch(info->s->keyinfo[inx].key_alg){
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case HA_KEY_ALG_BTREE:
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if (info->s->concurrent_insert)
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rw_unlock(&info->s->key_root_lock[inx]);
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fast_mi_writeinfo(info);
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DBUG_PRINT("info",("records: %ld",(ulong) (res)));
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/* Find relative position (in records) for key in index-tree */
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static ha_rows _mi_record_pos(MI_INFO *info, const unsigned char *key,
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static ha_rows _mi_record_pos(MI_INFO *info, const uchar *key,
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key_part_map keypart_map,
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enum ha_rkey_function search_flag)
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uint32_t inx=(uint) info->lastinx, nextflag, key_len;
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uint inx=(uint) info->lastinx, nextflag, key_len;
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MI_KEYDEF *keyinfo=info->s->keyinfo+inx;
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unsigned char *key_buff;
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DBUG_ENTER("_mi_record_pos");
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DBUG_PRINT("enter",("search_flag: %d",search_flag));
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DBUG_ASSERT(keypart_map);
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key_buff=info->lastkey+info->s->base.max_key_length;
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key_len=_mi_pack_key(info,inx,key_buff,(unsigned char*) key, keypart_map,
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key_len=_mi_pack_key(info,inx,key_buff,(uchar*) key, keypart_map,
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DBUG_EXECUTE("key",_mi_print_key(DBUG_FILE,keyinfo->seg,
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(uchar*) key_buff,key_len););
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nextflag=myisam_read_vec[search_flag];
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if (!(nextflag & (SEARCH_FIND | SEARCH_NO_FIND | SEARCH_LAST)))
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key_len=USE_WHOLE_KEY;
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info->s->state.key_root[inx]);
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return((uint32_t) (pos*info->state->records+0.5));
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DBUG_PRINT("exit",("pos: %ld",(ulong) (pos*info->state->records)));
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DBUG_RETURN((ulong) (pos*info->state->records+0.5));
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return(HA_POS_ERROR);
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DBUG_RETURN(HA_POS_ERROR);
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static double _mi_search_pos(register MI_INFO *info,
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register MI_KEYDEF *keyinfo,
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unsigned char *key, uint32_t key_len, uint32_t nextflag,
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register internal::my_off_t pos)
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uchar *key, uint key_len, uint nextflag,
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register my_off_t pos)
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uint32_t nod_flag, keynr, max_keynr= 0;
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unsigned char *keypos,*buff;
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uint nod_flag, keynr, max_keynr= 0;
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DBUG_ENTER("_mi_search_pos");
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if (pos == HA_OFFSET_ERROR)
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if (!(buff=_mi_fetch_keypage(info,keyinfo,pos,DFLT_INIT_HITS,info->buff,1)))
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if (flag == MI_FOUND_WRONG_KEY)
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return(-1); /* error */
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DBUG_RETURN(-1); /* error */
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Didn't found match. keypos points at next (bigger) key
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Try to find a smaller, better matching key.
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else if ((offset=_mi_search_pos(info,keyinfo,key,key_len,nextflag,
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_mi_kpos(nod_flag,keypos))) < 0)
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if ((offset=_mi_search_pos(info,keyinfo,key,key_len,SEARCH_FIND,
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_mi_kpos(nod_flag,keypos))) < 0)
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return(offset); /* Read error */
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DBUG_RETURN(offset); /* Read error */
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return((keynr+offset)/(max_keynr+1));
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DBUG_PRINT("info",("keynr: %d offset: %g max_keynr: %d nod: %d flag: %d",
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keynr,offset,max_keynr,nod_flag,flag));
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DBUG_RETURN((keynr+offset)/(max_keynr+1));
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DBUG_PRINT("exit",("Error: %d",my_errno));
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/* Get keynummer of current key and max number of keys in nod */
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static uint32_t _mi_keynr(MI_INFO *info, register MI_KEYDEF *keyinfo, unsigned char *page,
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unsigned char *keypos, uint32_t *ret_max_key)
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static uint _mi_keynr(MI_INFO *info, register MI_KEYDEF *keyinfo, uchar *page,
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uchar *keypos, uint *ret_max_key)
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uint32_t nod_flag,keynr,max_key;
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unsigned char t_buff[MI_MAX_KEY_BUFF],*end;
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uint nod_flag,keynr,max_key;
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uchar t_buff[MI_MAX_KEY_BUFF],*end;
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end= page+mi_getint(page);
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nod_flag=mi_test_if_nod(page);