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Fix for BUG#10037

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* Add 0.01 to cost of 'range'+'using index' scan to avoid optimizer choice races with 
  'index' scan.


mysql-test/r/range.result:
  Update the test result after the changed cost
sql/opt_range.cc:
  Fix for BUG#10037
  * Add 0.01 to cost of 'range'+'using index' scan to avoid optimizer choice races with 
    'index' scan.
  * make QUICK_GROUP_MIN_MAX_SELECT handle the case where the source table is empty.
This commit is contained in:
unknown
2005-04-21 01:55:33 +04:00
parent 241bedadeb
commit a52359e00c
2 changed files with 6 additions and 3 deletions
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5
sql/opt_range.cc
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@ -2257,7 +2257,8 @@ inline double get_index_only_read_time(const PARAM* param, ha_rows records,
param->table->file->ref_length) + 1);
read_time=((double) (records+keys_per_block-1)/
(double) keys_per_block);
return read_time;
/* Add 0.01 to avoid cost races between 'range' and 'index' */
return read_time + 0.01;
}
@ -7912,6 +7913,8 @@ int QUICK_GROUP_MIN_MAX_SELECT::reset(void)
file->extra(HA_EXTRA_KEYREAD); /* We need only the key attributes */
result= file->ha_index_init(index);
result= file->index_last(record);
if (result == HA_ERR_END_OF_FILE)
DBUG_RETURN(0);
if (result)
DBUG_RETURN(result);
if (quick_prefix_select && quick_prefix_select->reset())