diff options
Diffstat (limited to 'myisam/mi_range.c')
| -rw-r--r-- | myisam/mi_range.c | 72 |
1 files changed, 44 insertions, 28 deletions
diff --git a/myisam/mi_range.c b/myisam/mi_range.c index caa57ce6187..db01ada16dd 100644 --- a/myisam/mi_range.c +++ b/myisam/mi_range.c @@ -30,15 +30,27 @@ static uint _mi_keynr(MI_INFO *info,MI_KEYDEF *keyinfo,uchar *page, uchar *keypos,uint *ret_max_key); - /* If start_key = 0 assume read from start */ - /* If end_key = 0 assume read to end */ - /* Returns HA_POS_ERROR on error */ - -ha_rows mi_records_in_range(MI_INFO *info, int inx, const byte *start_key, - uint start_key_len, - enum ha_rkey_function start_search_flag, - const byte *end_key, uint end_key_len, - enum ha_rkey_function end_search_flag) +/* + Estimate how many records there is in a given range + + SYNOPSIS + mi_records_in_range() + info MyISAM handler + inx Index to use + min_key Min key. Is = 0 if no min range + max_key Max key. Is = 0 if no max range + + NOTES + We should ONLY return 0 if there is no rows in range + + RETURN + HA_POS_ERROR error (or we can't estimate number of rows) + number Estimated number of rows +*/ + + +ha_rows mi_records_in_range(MI_INFO *info, int inx, key_range *min_key, + key_range *max_key) { ha_rows start_pos,end_pos,res; DBUG_ENTER("mi_records_in_range"); @@ -54,27 +66,31 @@ ha_rows mi_records_in_range(MI_INFO *info, int inx, const byte *start_key, switch(info->s->keyinfo[inx].key_alg){ case HA_KEY_ALG_RTREE: - { - uchar * key_buff; - if (start_key_len == 0) - start_key_len=USE_WHOLE_KEY; - key_buff=info->lastkey+info->s->base.max_key_length; - start_key_len= _mi_pack_key(info,inx,key_buff,(uchar*) start_key, - start_key_len, (HA_KEYSEG**) 0); - res=rtree_estimate(info, inx, key_buff, start_key_len, myisam_read_vec[start_search_flag]); - res=res?res:1; - break; - } + { + uchar * key_buff; + uint start_key_len; + + key_buff= info->lastkey+info->s->base.max_key_length; + start_key_len= _mi_pack_key(info,inx, key_buff, + (uchar*) min_key->key, min_key->length, + (HA_KEYSEG**) 0); + res= rtree_estimate(info, inx, key_buff, start_key_len, + myisam_read_vec[min_key->flag]); + res= res ? res : 1; /* Don't return 0 */ + break; + } case HA_KEY_ALG_BTREE: default: - start_pos= (start_key ? - _mi_record_pos(info,start_key,start_key_len,start_search_flag) : - (ha_rows) 0); - end_pos= (end_key ? - _mi_record_pos(info,end_key,end_key_len,end_search_flag) : - info->state->records+ (ha_rows) 1); - res=end_pos < start_pos ? (ha_rows) 0 : - (end_pos == start_pos ? (ha_rows) 1 : end_pos-start_pos); + start_pos= (min_key ? + _mi_record_pos(info, min_key->key, min_key->length, + min_key->flag) : + (ha_rows) 0); + end_pos= (max_key ? + _mi_record_pos(info, max_key->key, max_key->length, + max_key->flag) : + info->state->records+ (ha_rows) 1); + res= (end_pos < start_pos ? (ha_rows) 0 : + (end_pos == start_pos ? (ha_rows) 1 : end_pos-start_pos)); if (start_pos == HA_POS_ERROR || end_pos == HA_POS_ERROR) res=HA_POS_ERROR; } |