MySQL Query optimization on big table - mysql

Question

I can't find a way to fasten simple queries in a huge table.
I don't think i'm asking something crazy to MySQL, even with the amount of datas… and i can't understand why these following queries have so much different execution time !
I tried my best to read all articles about big datas in mysql, fields optimization, and already achieved to reduce query time with field types… but really, i'm getting lost now with this kind of simple queries !
Here is an example on MySQL 5.1.69 :
SELECT rv.`id_prd`,SUM(`quantite`)
FROM `report_ventes` AS rv
WHERE `periode` BETWEEN 201301 AND 201312
GROUP BY rv.`id_prd`
Execution time : 3.76 sec
Let's add a LEFT JOIN and another selected field :
SELECT rv.`id_prd`,SUM(`quantite`),`acl_cip_7`
FROM `report_ventes` AS rv
LEFT JOIN `report_produits` AS rp
ON (rv.`id_prd` = rp.`id_prd`)
WHERE `periode` BETWEEN 201301 AND 201312
GROUP BY rv.`id_prd`
Execution time : 12.10 sec
Explain :
+----+-------------+-------+--------+---------------+---------+---------+--------------------------+----------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+--------+---------------+---------+---------+--------------------------+----------+----------------------------------------------+
| 1 | SIMPLE | rv | ALL | periode | NULL | NULL | NULL | 16556188 | Using where; Using temporary; Using filesort |
| 1 | SIMPLE | rp | eq_ref | PRIMARY | PRIMARY | 4 | main_reporting.rv.id_prd | 1 | Using index |
+----+-------------+-------+--------+---------------+---------+---------+--------------------------+----------+----------------------------------------------+
And let's another where clause :
SELECT rv.`id_prd`,SUM(`quantite`),`acl_cip_7`
FROM `report_ventes` AS rv
LEFT JOIN `report_produits` AS rp
ON (rv.`id_prd` = rp.`id_prd`)
WHERE rp.`id_clas_prd` LIKE '1%'
AND `periode` BETWEEN 201301 AND 201312
GROUP BY rv.`id_prd`
Execution time : 21.00 sec
Explain :
+----+-------------+-------+--------+---------------------+---------+---------+--------------------------+----------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+--------+---------------------+---------+---------+--------------------------+----------+----------------------------------------------+
| 1 | SIMPLE | rv | ALL | periode | NULL | NULL | NULL | 16556188 | Using where; Using temporary; Using filesort |
| 1 | SIMPLE | rp | eq_ref | PRIMARY,id_clas_prd | PRIMARY | 4 | main_reporting.rv.id_prd | 1 | Using where |
+----+-------------+-------+--------+---------------------+---------+---------+--------------------------+----------+----------------------------------------------+
And here are the tables parameters :
report_produits : 80 000 rows
CREATE TABLE `report_produits` (
`id_prd` int(11) unsigned NOT NULL,
`acl_cip_7` int(7) NOT NULL,
`acl_cip_ean_13` varchar(255) DEFAULT NULL,
`lib_prd` varchar(255) DEFAULT NULL,
`id_clas_prd` char(7) NOT NULL DEFAULT '',
`id_lab_prd` int(11) unsigned NOT NULL,
`id_rbt_prd` int(11) unsigned NOT NULL,
`id_tva_prd` int(11) unsigned NOT NULL,
`t_gen` varchar(255) NOT NULL,
`id_grp_gen` varchar(16) NOT NULL DEFAULT '',
`id_liste_delivrance` int(11) unsigned NOT NULL,
PRIMARY KEY (`id_prd`),
KEY `index_lab` (`id_lab_prd`),
KEY `index_grp` (`id_grp_gen`),
KEY `id_clas_prd` (`id_clas_prd`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
report_ventes : 16 556 188 rows
CREATE TABLE `report_ventes` (
`id` int(13) NOT NULL AUTO_INCREMENT,
`periode` mediumint(6) DEFAULT NULL,
`id_phie` smallint(4) unsigned NOT NULL,
`id_prd` mediumint(8) unsigned NOT NULL,
`quantite` smallint(11) DEFAULT NULL,
`ca_ht` decimal(10,2) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `periode` (`periode`)
) ENGINE=MyISAM AUTO_INCREMENT=18491315 DEFAULT CHARSET=utf8;

Answer 1

There is no covering index and MySQL decides that scanning the whole table is more effective than to use an index and lookup for the requested values.
You are joining to the report_ventes on the id_prd, but that column is not the part of the clustering index (PK in MySQL). This means, the server should lookup for all the values. The server bypasses the periode index possibly because it is not enough selective to use it.
An index could help which includes the id_prd, periode and quantite columns. With this index, there is a chance that the MySQL server will use it since it is a covering index for this query.
Give it a try, but its hard to tell the real truth without testing it on the actual environment.

Answer 2

Basically your indexes is not being used, i can't spot the precise reason without trying it on a sql server, but a common cause is the data has different types.
AND periode BETWEEN 201301 AND 201312
"periode" has datatype mediumint(6) and the litteral "201301" possible has datatype int(10)
LEFT JOIN `report_produits` AS rp ON (rv.`id_prd` = rp.`id_prd`)
Here are the 2 datatypes also different.