Hello Guys,
I have the following table:
CREATE TABLE tempo_resposta (
id int(11) NOT NULL auto_increment,
idmaquina int(11) NOT NULL default '0',
tempo int(11) NOT NULL default '0',
horario datetime NOT NULL default '0000-00-00 00:00:00',
PRIMARY KEY (id)
) TYPE=MyISAM;
In this table, I'll be running this query:
select tempo,unix_timestamp(now())-unix_timestamp(horario) as diferenca from
tempo_resposta where idmaquina=SOMEID order by diferenca desc
Right now, seems table is being completly scanned with this query:
mysql> explain select tempo,unix_timestamp(now())-unix_timestamp(horario) as
diferenca from tempo_resposta where idmaquina=23 order by diferenca desc;
+----------------+------+---------------+------+---------+------+------+----
-------------------------+
| table | type | possible_keys | key | key_len | ref | rows |
Extra |
+----------------+------+---------------+------+---------+------+------+----
-------------------------+
| tempo_resposta | ALL | NULL | NULL | NULL | NULL | 9216 |
Using where; Using filesort |
+----------------+------+---------------+------+---------+------+------+----
-------------------------+
1 row in set (0.00 sec)
rows=9216, exactly all rows in the table
Question: is there a way of creating an index for helping that kind of
query ? I've tried creating index on horario, but it doesnt helped.
Sincerily,
Leonardo Rodrigues
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