Hello All,

I have 2 queries, same same, but different in order by b.spot (in the end).
My question is regarding explain, why does it not effect performance ?

Thanks
Chanan

explain select count(b.id) amount_of_spot, count(distinct b.ukey) unique_player_count, sum(b.amount * b.currency_rate) sum_amount, b.spot from bet b where b.round_id = '2854170' and b.txn_status & '8' = '8' and b.txn_status & '16' = 0 group by b.spot order by b.spot asc;
+----+-------------+-------+------+-------------------------------+------------------+---------+-------+------+-----------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+------+-------------------------------+------------------+---------+-------+------+-----------------------------+
| 1 | SIMPLE | b | ref | bet_round_id,ind_roundId_ukey | ind_roundId_ukey | 4 | const | 68 | Using where; Using filesort |
+----+-------------+-------+------+-------------------------------+------------------+---------+-------+------+-----------------------------+
1 row in set (0.00 sec)



mysql> explain select count(b.id) amount_of_spot, count(distinct b.ukey) unique_player_count, sum(b.amount * b.currency_rate) sum_amount, b.spot from bet b where b.round_id = '2854170' and b.txn_status & '8' = '8' and b.txn_status & '16' = 0 group by b.spot;
+----+-------------+-------+------+-------------------------------+------------------+---------+-------+------+-----------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+------+-------------------------------+------------------+---------+-------+------+-----------------------------+
| 1 | SIMPLE | b | ref | bet_round_id,ind_roundId_ukey | ind_roundId_ukey | 4 | const | 68 | Using where; Using filesort |
+----+-------------+-------+------+-------------------------------+------------------+---------+-------+------+-----------------------------+
1 row in set (0.00 sec)

is it possible that group by had made the result sorted, and if using order by and group by same field - there is no performance change ?

-Chanan