Why is MySQL removing an existing index when adding a new one? - mysql

I'm adding a combined index to a table, but that index removes an already existing index (see how fk_service_catalog_parameter_component disappears). Any idea why?
mysql> show indexes from service_catalog_parameter;
+---------------------------+------------+----------------------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------------------+------------+----------------------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| service_catalog_parameter | 0 | PRIMARY | 1 | id | A | 0 | NULL | NULL | | BTREE | | |
| service_catalog_parameter | 1 | fk_service_catalog_parameter_resource | 1 | resource_id | A | 0 | NULL | NULL | YES | BTREE | | |
| service_catalog_parameter | 1 | fk_service_catalog_parameter_component | 1 | component_id | A | 0 | NULL | NULL | YES | BTREE | | |
+---------------------------+------------+----------------------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
3 rows in set (0.00 sec)
mysql> ALTER TABLE `service_catalog_parameter` ADD UNIQUE INDEX `resource_parameter_component_unique` (`component_id`, `resource_id`, `parameter_name`);
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> show indexes from service_catalog_parameter;
+---------------------------+------------+---------------------------------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------------------+------------+---------------------------------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| service_catalog_parameter | 0 | PRIMARY | 1 | id | A | 0 | NULL | NULL | | BTREE | | |
| service_catalog_parameter | 0 | resource_parameter_component_unique | 1 | component_id | A | 0 | NULL | NULL | YES | BTREE | | |
| service_catalog_parameter | 0 | resource_parameter_component_unique | 2 | resource_id | A | 0 | NULL | NULL | YES | BTREE | | |
| service_catalog_parameter | 0 | resource_parameter_component_unique | 3 | parameter_name | A | 0 | NULL | NULL | | BTREE | | |
| service_catalog_parameter | 1 | fk_service_catalog_parameter_resource | 1 | resource_id | A | 0 | NULL | NULL | YES | BTREE | | |
+---------------------------+------------+---------------------------------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
5 rows in set (0.00 sec)
mysql>
My head totally blows up when I change the order of the columns in the index.
mysql> show indexes from service_catalog_parameter;
+---------------------------+------------+----------------------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------------------+------------+----------------------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| service_catalog_parameter | 0 | PRIMARY | 1 | id | A | 0 | NULL | NULL | | BTREE | | |
| service_catalog_parameter | 1 | fk_service_catalog_parameter_resource | 1 | resource_id | A | 0 | NULL | NULL | YES | BTREE | | |
| service_catalog_parameter | 1 | fk_service_catalog_parameter_component | 1 | component_id | A | 0 | NULL | NULL | YES | BTREE | | |
+---------------------------+------------+----------------------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
3 rows in set (0.01 sec)
mysql> ALTER TABLE `service_catalog_parameter` ADD UNIQUE INDEX `resource_parameter_component_unique` (`parameter_name`, `component_id`, `resource_id`);
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> show indexes from service_catalog_parameter;
+---------------------------+------------+----------------------------------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------------------+------------+----------------------------------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| service_catalog_parameter | 0 | PRIMARY | 1 | id | A | 0 | NULL | NULL | | BTREE | | |
| service_catalog_parameter | 0 | resource_parameter_component_unique | 1 | parameter_name | A | 0 | NULL | NULL | | BTREE | | |
| service_catalog_parameter | 0 | resource_parameter_component_unique | 2 | component_id | A | 0 | NULL | NULL | YES | BTREE | | |
| service_catalog_parameter | 0 | resource_parameter_component_unique | 3 | resource_id | A | 0 | NULL | NULL | YES | BTREE | | |
| service_catalog_parameter | 1 | fk_service_catalog_parameter_resource | 1 | resource_id | A | 0 | NULL | NULL | YES | BTREE | | |
| service_catalog_parameter | 1 | fk_service_catalog_parameter_component | 1 | component_id | A | 0 | NULL | NULL | YES | BTREE | | |
+---------------------------+------------+----------------------------------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
6 rows in set (0.00 sec)
mysql>

Related

How to improve this query mysql and rails 5

We have three tables users, stores and store_customer_associations, where a user can be a customer for many stores.
I've tried to place another index in primary key but without success (and other too).
(currently these are our indexes in each table)
mysql> SHOW INDEXES FROM store_customer_associations;
+-------+------------+-------------------------------------+--------------+----------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+-------------------------------------+--------------+----------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| users | 0 | PRIMARY | 1 | id | A | 9386515 | NULL | NULL | | BTREE | | |
| users | 0 | tmp_idx_users_id | 1 | id | A | 9386515 | NULL | NULL | | BTREE | | |
+-------+------------+-------------------------------------+--------------+----------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
10 rows in set (0.00 sec)
mysql> SHOW INDEXES FROM store_customer_associations;
+-----------------------------+------------+-----------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-----------------------------+------------+-----------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| store_customer_associations | 0 | PRIMARY | 1 | id | A | 51298761 | NULL | NULL | | BTREE | | |
| store_customer_associations | 1 | index_store_customer_associations_on_store_id | 1 | store_id | A | 50096 | NULL | NULL | YES | BTREE | | |
| store_customer_associations | 1 | index_store_customer_associations_on_user_id | 1 | user_id | A | 25649380 | NULL | NULL | YES | BTREE | | |
+-----------------------------+------------+-----------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
3 rows in set (0.00 sec)
We are using rails 5.1 (this is a big rails 4 legacy database).
Then we need to make this query fast:
SELECT COUNT(*)
FROM `users`
INNER JOIN `store_customer_associations`
ON `users`.`id` = `store_customer_associations`.`user_id`
WHERE `store_customer_associations`.`store_id` = STORE_ID;
+----------+
| COUNT(*) |
+----------+
| 1997632 |
+----------+
1 row in set (6.64 sec)
mysql> EXPLAIN SELECT COUNT(*)
FROM `users`
INNER JOIN `store_customer_associations`
ON `users`.`id` = `store_customer_associations`.`user_id`
WHERE `store_customer_associations`.`store_id` = STORE_ID;
+------+-------------+-----------------------------+--------+--------------------------------------------------------------------------------------------+-----------------------------------------------+---------+---------------------------------------------------------+---------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-----------------------------+--------+--------------------------------------------------------------------------------------------+-----------------------------------------------+---------+---------------------------------------------------------+---------+-------------+
| 1 | SIMPLE | store_customer_associations | ref | index_store_customer_associations_on_store_id,index_store_customer_associations_on_user_id | index_store_customer_associations_on_store_id | 5 | const | 4401812 | Using where |
| 1 | SIMPLE | users | eq_ref | PRIMARY,tmp_idx_users_id | PRIMARY | 4 | trustvox_production.store_customer_associations.user_id | 1 | Using index |
+------+-------------+-----------------------------+--------+--------------------------------------------------------------------------------------------+-----------------------------------------------+---------+---------------------------------------------------------+---------+-------------+
2 rows in set (0.00 sec)
UPDATE 1
mysql> EXPLAIN SELECT COUNT(*)
FROM `users`
INNER JOIN `store_customer_associations`
ON `users`.`id` = `store_customer_associations`.`user_id`
WHERE `store_customer_associations`.`store_id` = STORE_ID;
+------+-------------+-----------------------------+--------+-------------------------------------------------------------------------------------------------------------+-----------------------------------------------+---------+---------------------------------------------------------+---------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-----------------------------+--------+-------------------------------------------------------------------------------------------------------------+-----------------------------------------------+---------+---------------------------------------------------------+---------+-------------+
| 1 | SIMPLE | store_customer_associations | ref | index_store_customer_associations_on_store_id,index_store_customer_associations_on_user_id,user_id_store_id | index_store_customer_associations_on_store_id | 5 | const | 4401812 | Using where |
| 1 | SIMPLE | users | eq_ref | PRIMARY,tmp_idx_users_id | PRIMARY | 4 | trustvox_production.store_customer_associations.user_id | 1 | Using index |
+------+-------------+-----------------------------+--------+-------------------------------------------------------------------------------------------------------------+-----------------------------------------------+---------+---------------------------------------------------------+---------+-------------+
2 rows in set (0.00 sec)
UPDATE 2
mysql> SELECT COUNT(*)
FROM users
INNER JOIN store_customer_associations
FORCE INDEX FOR JOIN (PRIMARY, user_id_store_id)
ON users.id = store_customer_associations.user_id
WHERE store_customer_associations.store_id = STORE_ID;
+----------+
| COUNT(*) |
+----------+
| 1997632 |
+----------+
1 row in set (28.90 sec)
mysql> EXPLAIN SELECT COUNT(*)
FROM users
INNER JOIN store_customer_associations
FORCE INDEX FOR JOIN (PRIMARY, user_id_store_id)
ON users.id = store_customer_associations.user_id
WHERE store_customer_associations.store_id = STORE_ID;
+------+-------------+-----------------------------+-------+--------------------------+------------------+---------+------------------------------------+---------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-----------------------------+-------+--------------------------+------------------+---------+------------------------------------+---------+-------------+
| 1 | SIMPLE | users | index | PRIMARY,tmp_idx_users_id | tmp_idx_users_id | 4 | NULL | 8675689 | Using index |
| 1 | SIMPLE | store_customer_associations | ref | user_id_store_id | user_id_store_id | 10 | trustvox_production.users.id,const | 1 | Using index |
+------+-------------+-----------------------------+-------+--------------------------+------------------+---------+------------------------------------+---------+-------------+
2 rows in set (0.00 sec)
mysql>
UPDATE 3
mysql> EXPLAIN SELECT COUNT(*)
FROM users
INNER JOIN
( SELECT *
FROM store_customer_associations
WHERE store_id = 75856
) sca ON users.id = sca.user_id;
+------+-------------+-----------------------------+--------+-------------------------------------------------------------------------------------------------------------+-----------------------------------------------+---------+---------------------------------------------------------+---------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-----------------------------+--------+-------------------------------------------------------------------------------------------------------------+-----------------------------------------------+---------+---------------------------------------------------------+---------+-------------+
| 1 | SIMPLE | store_customer_associations | ref | index_store_customer_associations_on_store_id,index_store_customer_associations_on_user_id,user_id_store_id | index_store_customer_associations_on_store_id | 5 | const | 4401812 | Using where |
| 1 | SIMPLE | users | eq_ref | PRIMARY,tmp_idx_users_id | PRIMARY | 4 | trustvox_production.store_customer_associations.user_id | 1 | Using index |
+------+-------------+-----------------------------+--------+-------------------------------------------------------------------------------------------------------------+-----------------------------------------------+---------+---------------------------------------------------------+---------+-------------+
UPDATE 4
mysql> ALTER TABLE store_customer_associations DROP INDEX index_store_customer_associations_on_store_id;
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> ALTER TABLE store_customer_associations DROP INDEX index_store_customer_associations_on_user_id;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> CREATE INDEX index_on_store_id_and_user_id ON store_customer_associations (store_id, user_id);
Query OK, 0 rows affected (45.95 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> CREATE INDEX index_store_customer_associations_on_user_id ON store_customer_associations(user_id);
Query OK, 0 rows affected (33.06 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> CREATE INDEX index_store_customer_associations_on_store_id ON store_customer_associations(store_id);
Query OK, 0 rows affected (38.58 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> SHOW INDEXES FROM store_customer_associations;
+-----------------------------+------------+-----------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-----------------------------+------------+-----------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| store_customer_associations | 0 | PRIMARY | 1 | id | A | 10305620 | NULL | NULL | | BTREE | | |
| store_customer_associations | 1 | index_on_store_id_and_user_id | 1 | store_id | A | 8244 | NULL | NULL | YES | BTREE | | |
| store_customer_associations | 1 | index_on_store_id_and_user_id | 2 | user_id | A | 10305620 | NULL | NULL | YES | BTREE | | |
| store_customer_associations | 1 | index_store_customer_associations_on_user_id | 1 | user_id | A | 10305620 | NULL | NULL | YES | BTREE | | |
| store_customer_associations | 1 | index_store_customer_associations_on_store_id | 1 | store_id | A | 6424 | NULL | NULL | YES | BTREE | | |
+-----------------------------+------------+-----------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
5 rows in set (0.00 sec)

store_customer_associations: INDEX(store_id, user_id) -- "covering"
store_id is first -- to handle the WHERE; user_id is added so that the only the index need by touched.
A tutorial that lets you discover the INDEX yourself: http://mysql.rjweb.org/doc.php/index_cookbook_mysql

U need to make index for 2 parameters for store_curstometer_associations because in query index is not because where part.
create index user_id_store_id on store_customer_associations (user_id, store_id)
Should help u out
Example
mysql> show indexes from api_plexts;
+------------+------------+----------------------------------------+--------------+--------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+------------+------------+----------------------------------------+--------------+--------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| api_plexts | 0 | PRIMARY | 1 | id | A | 206318 | NULL | NULL | | BTREE | | |
| api_plexts | 0 | index_api_plexts_on_guid | 1 | guid | A | 215475 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | index_api_plexts_on_api_agent_id | 1 | api_agent_id | A | 1565 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | index_api_plexts_on_from_api_portal_id | 1 | from_api_portal_id | A | 11401 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | index_api_plexts_on_to_api_portal_id | 1 | to_api_portal_id | A | 9566 | NULL | NULL | YES | BTREE | | |
+------------+------------+----------------------------------------+--------------+--------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
5 rows in set (0.00 sec)
mysql> show indexes from api_portals;
+-------------+------------+--------------------------------------+--------------+-----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------------+------------+--------------------------------------+--------------+-----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| api_portals | 0 | PRIMARY | 1 | id | A | 20530 | NULL | NULL | | BTREE | | |
| api_portals | 0 | index_api_portals_on_guid | 1 | guid | A | 19891 | NULL | NULL | YES | BTREE | | |
| api_portals | 1 | index_api_portals_on_owner_agent_id | 1 | owner_agent_id | A | 718 | NULL | NULL | YES | BTREE | | |
| api_portals | 1 | index_api_portals_on_api_map_tile_id | 1 | api_map_tile_id | A | 5480 | NULL | NULL | YES | BTREE | | |
+-------------+------------+--------------------------------------+--------------+-----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
explain select count(*) from api_portals ap JOIN api_plexts al FORCE INDEX FOR JOIN (PRIMARY) on ap.id = al.from_api_portal_id where al.api_agent_id = 2\G;
mysql> show indexes from api_plexts;
+------------+------------+----------------------------------------+--------------+--------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+------------+------------+----------------------------------------+--------------+--------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| api_plexts | 0 | PRIMARY | 1 | id | A | 206318 | NULL | NULL | | BTREE | | |
| api_plexts | 0 | index_api_plexts_on_guid | 1 | guid | A | 215475 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | index_api_plexts_on_api_agent_id | 1 | api_agent_id | A | 1565 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | index_api_plexts_on_from_api_portal_id | 1 | from_api_portal_id | A | 11401 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | index_api_plexts_on_to_api_portal_id | 1 | to_api_portal_id | A | 9566 | NULL | NULL | YES | BTREE | | |
+------------+------------+----------------------------------------+--------------+--------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
5 rows in set (0.00 sec)
mysql> show indexes from api_portals;
+-------------+------------+--------------------------------------+--------------+-----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------------+------------+--------------------------------------+--------------+-----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| api_portals | 0 | PRIMARY | 1 | id | A | 20530 | NULL | NULL | | BTREE | | |
| api_portals | 0 | index_api_portals_on_guid | 1 | guid | A | 19891 | NULL | NULL | YES | BTREE | | |
| api_portals | 1 | index_api_portals_on_owner_agent_id | 1 | owner_agent_id | A | 718 | NULL | NULL | YES | BTREE | | |
| api_portals | 1 | index_api_portals_on_api_map_tile_id | 1 | api_map_tile_id | A | 5480 | NULL | NULL | YES | BTREE | | |
+-------------+------------+--------------------------------------+--------------+-----------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
mysql> explain select count(*) from api_portals ap JOIN api_plexts al on ap.id = al.from_api_portal_id where al.api_agent_id = 2;
+----+-------------+-------+------------+--------+-------------------------------------------------------------------------+----------------------------------+---------+-------------------------------+------+----------+--------------------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+-------+------------+--------+-------------------------------------------------------------------------+----------------------------------+---------+-------------------------------+------+----------+--------------------------+
| 1 | SIMPLE | al | NULL | ref | index_api_plexts_on_api_agent_id,index_api_plexts_on_from_api_portal_id | index_api_plexts_on_api_agent_id | 5 | const | 271 | 100.00 | Using where |
| 1 | SIMPLE | ap | NULL | eq_ref | PRIMARY | PRIMARY | 8 | ingress.al.from_api_portal_id | 1 | 100.00 | Using where; Using index |
+----+-------------+-------+------------+--------+-------------------------------------------------------------------------+----------------------------------+---------+-------------------------------+------+----------+--------------------------+
this is exactly your case U can see using where
mysql> create index testime on api_plexts (api_agent_id, from_api_portal_id); Query OK, 0 rows affected (3.71 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> show indexes from api_plexts;
+------------+------------+----------------------------------------+--------------+--------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+------------+------------+----------------------------------------+--------------+--------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| api_plexts | 0 | PRIMARY | 1 | id | A | 200644 | NULL | NULL | | BTREE | | |
| api_plexts | 0 | index_api_plexts_on_guid | 1 | guid | A | 209549 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | index_api_plexts_on_api_agent_id | 1 | api_agent_id | A | 1522 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | index_api_plexts_on_from_api_portal_id | 1 | from_api_portal_id | A | 11087 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | index_api_plexts_on_to_api_portal_id | 1 | to_api_portal_id | A | 9303 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | testime | 1 | api_agent_id | A | 1817 | NULL | NULL | YES | BTREE | | |
| api_plexts | 1 | testime | 2 | from_api_portal_id | A | 52277 | NULL | NULL | YES | BTREE | | |
+------------+------------+----------------------------------------+--------------+--------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
7 rows in set (0.00 sec)
VOILA!!!
mysql> explain select count(*) from api_portals ap JOIN api_plexts al on ap.id = al.from_api_portal_id where al.api_agent_id = 2\G; *************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: al
partitions: NULL
type: ref
possible_keys: index_api_plexts_on_api_agent_id,index_api_plexts_on_from_api_portal_id,testime
key: testime
key_len: 5
ref: const
rows: 271
filtered: 100.00
Extra: Using where; Using index
*************************** 2. row ***************************
id: 1
select_type: SIMPLE
table: ap
partitions: NULL
type: eq_ref
possible_keys: PRIMARY
key: PRIMARY
key_len: 8
ref: ingress.al.from_api_portal_id
rows: 1
filtered: 100.00
Extra: Using where; Using index
2 rows in set, 1 warning (0.00 sec)

MySQL indexing long running queries - Are keys used?

I am working on large tables of my database (mysql). Some of my queries are running more than 5 minutes. Here is an example of my query that is running slow:
select b.DESCRIPTION collateral_type, a.description brand, a.year,
a.model, a.plate_number, d.description fuel, a.chassis_number,
a.engine_number, c.description as color, insurance_name
from lms_loan_application_collateral a inner join
lms_collateral_type b
on a.COLLATERAL_TYPE_ID = b.id left join
lms_color c
on a.color_id = c.id left join
lms_fuel_type d
on a.fuel_type_id = d.id inner join
lms_loan_application e
on e.id = a.loan_application_id inner join
lms_dlr_dtl f
on e.code = f.lano inner join
lms_loanapp_dtl g
on f.lano = g.lano
where b.description in ('Motorcycle', 'Automotive', 'Heavy Equipment');
here is a mysql explain of the query
+----+-------------+-------+-------+--------------------------------------------------------+-------------------------+---------+------------+-------+----------------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+--------------------------------------------------------+-------------------------+---------+------------+-------+----------------------------------------------------+
| 1 | SIMPLE | g | index | lms_loanapp_dtl_lano | lms_loanapp_dtl_lano | 23 | NULL | 23432 | Using where; Using index |
| 1 | SIMPLE | f | ref | lano | lano | 23 | new.g.LANO | 1 | Using index |
| 1 | SIMPLE | b | ALL | lms_collateral_type_description,lms_collateral_type_id | NULL | NULL | NULL | 11 | Using where; Using join buffer (Block Nested Loop) |
| 1 | SIMPLE | a | ref | collateral_type_id | collateral_type_id | 5 | new.b.ID | 4067 | Using index condition |
| 1 | SIMPLE | e | ref | lms_loan_application_id | lms_loan_application_id | 153 | func | 1 | Using index condition; Using where |
| 1 | SIMPLE | c | ALL | LMS_color_id | NULL | NULL | NULL | 20 | Range checked for each record (index map: 0x1) |
| 1 | SIMPLE | d | ALL | LMS_fuel_type_id | NULL | NULL | NULL | 4 | Using where; Using join buffer (Block Nested Loop) |
+----+-------------+-------+-------+--------------------------------------------------------+-------------------------+---------+------------+-------+----------------------------------------------------+
under the key column, there are NULL values. I am not sure if mysql uses the index keys I have created.
Below is the list of indexes I created for the involved tables:
SHOW INDEX FROM lms_loan_application_collateral FROM new;
+---------------------------------+------------+---------------------+--------------+---------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------------------------+------------+---------------------+--------------+---------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| lms_loan_application_collateral | 1 | color_id | 1 | color_id | A | 36 | NULL | NULL | YES | BTREE | | |
| lms_loan_application_collateral | 1 | fuel_type_id | 1 | fuel_type_id | A | 6 | NULL | NULL | YES | BTREE | | |
| lms_loan_application_collateral | 1 | loan_application_id | 1 | loan_application_id | A | 89493 | NULL | NULL | YES | BTREE | | |
| lms_loan_application_collateral | 1 | collateral_type_id | 1 | collateral_type_id | A | 22 | NULL | NULL | YES | BTREE | | |
+---------------------------------+------------+---------------------+--------------+---------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
SHOW INDEX FROM lms_collateral_type FROM new;
+---------------------+------------+---------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------------+------------+---------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| lms_collateral_type | 1 | lms_collateral_type_description | 1 | DESCRIPTION | A | 11 | NULL | NULL | YES | BTREE | | |
| lms_collateral_type | 1 | lms_collateral_type_id | 1 | ID | A | 11 | NULL | NULL | YES | BTREE | | |
+---------------------+------------+---------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
SHOW INDEX FROM lms_color FROM new;
+-----------+------------+--------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-----------+------------+--------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| lms_color | 1 | LMS_color_id | 1 | id | A | 20 | NULL | NULL | | BTREE | | |
+-----------+------------+--------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
SHOW INDEX FROM lms_fuel_type FROM new;
+---------------+------------+------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------+------------+------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| lms_fuel_type | 1 | LMS_fuel_type_id | 1 | id | A | 4 | NULL | NULL | YES | BTREE | | |
+---------------+------------+------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
SHOW INDEX FROM lms_loan_application FROM new;
+----------------------+------------+-------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+----------------------+------------+-------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| lms_loan_application | 1 | lmspis_id | 1 | PIS_ID | A | 1878 | NULL | NULL | YES | BTREE | | |
| lms_loan_application | 1 | loan_type_id | 1 | LOAN_TYPE_ID | A | 6 | NULL | NULL | YES | BTREE | | |
| lms_loan_application | 1 | lms_loan_application_id | 1 | ID | A | 1878 | NULL | NULL | YES | BTREE | | |
+----------------------+------------+-------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
SHOW INDEX FROM lms_dlr_dtl FROM new;
+-------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| lms_dlr_dtl | 0 | PRIMARY | 1 | LDDID | A | 90066 | NULL | NULL | | BTREE | | |
| lms_dlr_dtl | 1 | lano | 1 | LANO | A | 90066 | NULL | NULL | YES | BTREE | | |
+-------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
SHOW INDEX FROM lms_loanapp_dtl FROM new;
+-----------------+------------+----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-----------------+------------+----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| lms_loanapp_dtl | 0 | PRIMARY | 1 | LLADID | A | 23432 | NULL | NULL | | BTREE | | |
| lms_loanapp_dtl | 1 | lms_loanapp_dtl_lano | 1 | LANO | A | 23432 | NULL | NULL | YES | BTREE | | |
+-----------------+------------+----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+

The tables which indicates the type as ALL does not utilise the indexes. Create indexes on id column on tables represents in c and d and one index on both description and id columns on b.
create index ix_id on lms_color(id);
create index ix_id on lms_fuel_type(id);
create index ix_description_id on lms_collateral_type(description,id);

MySQL is using ALL for your WHERE because of low cardinality. So MySQL thinks it is cheaper to just doing table scan over 11 entries than using binary search with index.
The real problem is that you do not filter using column whose index has higher cardinality (lms_loanapp_dtl_lano and collateral_type_id).

MySQL explain - require index suggestions / feedback [closed]

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I have a database containing around 5million rows and am having issues with a query taking a long time (over a minute). I was hoping this information would be enough for someone to give me some suggestions, if I need to post more information just let me know.
Thank you in advance for any advice
EXPLAIN SELECT count( * ) AS count
FROM vtiger_time
INNER JOIN vtiger_crmentity ON vtiger_crmentity.crmid = vtiger_time.timeid
INNER JOIN vtiger_crmentityrel ON ( vtiger_crmentityrel.relcrmid = vtiger_crmentity.crmid
OR vtiger_crmentityrel.crmid = vtiger_crmentity.crmid )
LEFT JOIN vtiger_users ON vtiger_users.id = vtiger_crmentity.smownerid
LEFT JOIN vtiger_groups ON vtiger_groups.groupid = vtiger_crmentity.smownerid
WHERE vtiger_crmentity.deleted =0
AND (
vtiger_crmentityrel.crmid =211294
OR vtiger_crmentityrel.relcrmid =211294
)
+----+-------------+---------------------+-------------+-------------------------------------------------+----------------+---------+--------------------------------+-------+------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------------+-------------+-------------------------------------------------+----------------+---------+--------------------------------+-------+------------------------------------------+
| 1 | SIMPLE | vtiger_crmentityrel | index_merge | crmid,relcrmid | crmid,relcrmid | 4,4 | NULL | 5881 | Using union(crmid,relcrmid); Using where |
| 1 | SIMPLE | vtiger_crmentity | ref | PRIMARY,deleted,deleted_2,crmentity_multi_index | deleted_2 | 4 | const | 84424 | Using where; Using index |
| 1 | SIMPLE | vtiger_users | eq_ref | PRIMARY | PRIMARY | 4 | crm.vtiger_crmentity.smownerid | 1 | Using index |
| 1 | SIMPLE | vtiger_groups | eq_ref | PRIMARY | PRIMARY | 4 | crm.vtiger_crmentity.smownerid | 1 | Using index |
| 1 | SIMPLE | vtiger_time | eq_ref | PRIMARY,timeid | PRIMARY | 4 | crm.vtiger_crmentity.crmid | 1 | Using index |
+----+-------------+---------------------+-------------+-------------------------------------------------+----------------+---------+--------------------------------+-------+------------------------------------------+
Additionally these are my currently set indexes
+------------------+------------+----------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+------------------+------------+----------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| vtiger_crmentity | 0 | PRIMARY | 1 | crmid | A | 755968 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 0 | crmid | 1 | crmid | A | 755968 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | crmentity_IDX0 | 1 | smcreatorid | A | 15 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | crmentity_IDX1 | 1 | smownerid | A | 15 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | crmentity_IDX2 | 1 | modifiedby | A | 15 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | deleted | 1 | deleted | A | 15 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | deleted | 2 | smownerid | A | 15 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | smownerid | 1 | smownerid | A | 199 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | smownerid | 2 | deleted | A | 199 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | deleted_2 | 1 | deleted | A | 15 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | deleted_2 | 2 | smownerid | A | 15 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | smownerid_2 | 1 | smownerid | A | 385 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | smownerid_2 | 2 | deleted | A | 758 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | crm_ownerid_del_setype_idx | 1 | smownerid | A | 15 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | crm_ownerid_del_setype_idx | 2 | deleted | A | 15 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | crm_ownerid_del_setype_idx | 3 | setype | A | 613 | NULL | NULL | YES | BTREE | |
| vtiger_crmentity | 1 | crmentity_multi_index | 1 | crmid | A | 755968 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | crmentity_multi_index | 2 | smownerid | A | 755968 | NULL | NULL | | BTREE | |
| vtiger_crmentity | 1 | crmentity_multi_index | 3 | deleted | A | 755968 | NULL | NULL | | BTREE | |
+------------------+------------+----------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
+---------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+---------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| vtiger_crmentityrel | 1 | crmid | 1 | crmid | A | 223960 | NULL | NULL | | BTREE | |
| vtiger_crmentityrel | 1 | relcrmid | 1 | relcrmid | A | 12442 | NULL | NULL | | BTREE | |
+---------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
+--------------+------------+---------------+--------------+---------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+--------------+------------+---------------+--------------+---------------+-----------+-------------+----------+--------+------+------------+---------+
| vtiger_users | 0 | PRIMARY | 1 | id | A | 39 | NULL | NULL | | BTREE | |
| vtiger_users | 1 | idx_user_name | 1 | user_name | A | 39 | NULL | NULL | YES | BTREE | |
| vtiger_users | 1 | user_password | 1 | user_password | A | 39 | NULL | NULL | YES | BTREE | |
+--------------+------------+---------------+--------------+---------------+-----------+-------------+----------+--------+------+------------+---------+
+---------------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+---------------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| vtiger_groups | 0 | PRIMARY | 1 | groupid | A | 5 | NULL | NULL | | BTREE | |
| vtiger_groups | 1 | groupname | 1 | groupname | A | 5 | NULL | NULL | YES | BTREE | |
| vtiger_groups | 1 | idx_groups_123group | 1 | groupname | A | 5 | NULL | NULL | YES | BTREE | |
+---------------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
+----------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+----------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| vtiger_time | 0 | PRIMARY | 1 | timeid | A | 591772 | NULL | NULL | | BTREE | |
| vtiger_time | 0 | timeid | 1 | timeid | A | 591772 | NULL | NULL | | BTREE | |
| vtiger_time | 1 | relatedto | 1 | relatedto | A | 1405 | NULL | NULL | YES | BTREE | |
| vtiger_time | 1 | date_start | 1 | date_start | A | 7129 | NULL | NULL | YES | BTREE | |
| vtiger_time | 1 | relatedto_2 | 1 | relatedto | A | 3269 | NULL | NULL | YES | BTREE | |
+----------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
+------------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+------------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| vtiger_timecf | 0 | PRIMARY | 1 | timeid | A | 591324 | NULL | NULL | | BTREE | |
| vtiger_timecf | 0 | timeid | 1 | timeid | A | 591324 | NULL | NULL | | BTREE | |
| vtiger_timecf | 1 | timeid_2 | 1 | timeid | A | 591324 | NULL | NULL | | BTREE | |
+------------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
After adding the following index
ALTER TABLE vtiger_crmentity ADD INDEX TMP_deletion_smownerid_crmid (smownerid, deleted,crmid);
The new explain:
+----+-------------+---------------------+-------------+--------------------------------------------------------------------------+----------------+---------+--------------------------------+-------+------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------------+-------------+--------------------------------------------------------------------------+----------------+---------+--------------------------------+-------+------------------------------------------+
| 1 | SIMPLE | vtiger_crmentityrel | index_merge | crmid,relcrmid | crmid,relcrmid | 4,4 | NULL | 5891 | Using union(crmid,relcrmid); Using where |
| 1 | SIMPLE | vtiger_crmentity | ref | PRIMARY,crmid,deleted,deleted_2,crmentity_multi_index,_deletion_crmid | deleted | 4 | const | 84424 | Using where; Using index |
| 1 | SIMPLE | vtiger_users | eq_ref | PRIMARY | PRIMARY | 4 | crm.vtiger_crmentity.smownerid | 1 | Using index |
| 1 | SIMPLE | vtiger_groups | eq_ref | PRIMARY | PRIMARY | 4 | crm.vtiger_crmentity.smownerid | 1 | Using index |
| 1 | SIMPLE | vtiger_time | eq_ref | PRIMARY,timeid | PRIMARY | 4 | crm.vtiger_crmentity.crmid | 1 | Using index |
+----+-------------+---------------------+-------------+--------------------------------------------------------------------------+----------------+---------+--------------------------------+-------+------------------------------------------+

Rewriting the query would help, but since you cannot do that, you may benefit from a composite index on vtiger_crmentity.crmid and vtiger_crmentity.deleted. But since it isn't using one of the the index you currently have on vtiger_crmentity.crmid, it might not use that new one. If it doesn't, try adding vtiger_crmentity.crmid to the vtiger_crmentity.deleted index. Since it is already using the index on vtiger_crmentity.deleted, this will make the index a covering index so the query will not need to read from the table.
As I mentioned in my comment, there are a lot of duplicate indexes. The won't affect the query for this question, but they will slow down inserts and increase table size. The following indexes are redundant:
vtiger_crmentity.crmid
vtiger_crmentity.smownerid
vtiger_crmentity.smownerid_2
vtiger_crmentity.deleted_2
vtiger_groups.idx_groups_123group
vtiger_time.timeid
vtiger_time.relatedto_2
vtiger_timecf.timeid
vtiger_timcfe.timeid_2
You also shouldn't need the index on the user password column since you shouldn't be looking for users by password.

Try adding this index:
ALTER TABLE vtiger_crmentityrel ADD INDEX ix_crmentityrel_crmid_relcrmid (crmid,relcrmid);
This should allow the first row in the explain to be satisfied completely by the two indexes on the crmentityrel table and should save you a few thousand lookups.
All other parts of the execution plan are using covering indexes so if this doesn't help, I'm not sure there is much more you can do without restructuring the data or the query.

Can I optimize this kind of query?

I have this query:
SELECT
s.last_spread, s.sd, s.mean, s.id
,c.id_ticker, c.coef
,t.ticker
,p.last, p.price
FROM (SELECT * FROM spreads WHERE spreads.id_check=1 LIMIT 100,500 ) as s
INNER JOIN coef as c
ON c.id_spread = s.id
INNER JOIN tickers AS t
ON t.id = c.id_ticker
LEFT JOIN (SELECT prices.id_ticker, MAX(prices.date) as last, prices.price FROM prices GROUP BY prices.id_ticker) AS p
ON p.id_ticker = t.id
These are the schemas of the tables:
mysql> desc spreads;
+-------------+---------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+---------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| id_check | int(11) | YES | MUL | NULL | |
| sd | double | YES | | NULL | |
| mean | double | YES | | NULL | |
| last_spread | double | YES | | NULL | |
+-------------+---------+------+-----+---------+----------------+
5 rows in set (0.00 sec)
mysql> desc coef;
+-----------+---------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+---------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| id_spread | int(11) | YES | MUL | NULL | |
| id_ticker | int(11) | YES | | NULL | |
| coef | double | YES | | NULL | |
| side | double | YES | | NULL | |
+-----------+---------+------+-----+---------+----------------+
5 rows in set (0.00 sec)
mysql> desc tickers;
+----------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+------------------+------+-----+---------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| ticker | varchar(45) | NO | | NULL | |
| name | varchar(150) | NO | | NULL | |
| category | varchar(150) | NO | | NULL | |
| issuer | varchar(150) | NO | | NULL | |
+----------+------------------+------+-----+---------+----------------+
5 rows in set (0.00 sec)
mysql> desc prices;
+-----------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+------------------+------+-----+---------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| id_ticker | int(10) unsigned | NO | MUL | NULL | |
| date | date | NO | | NULL | |
| price | double | NO | | NULL | |
+-----------+------------------+------+-----+---------+----------------+
4 rows in set (0.01 sec)
These are the indexes of the above tables;
mysql> show indexes from spreads;
+---------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+---------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| spreads | 0 | PRIMARY | 1 | id | A | 2299 | NULL | NULL | | BTREE | |
| spreads | 1 | check_idx | 1 | id_check | A | 1 | NULL | NULL | YES | BTREE | |
+---------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
2 rows in set (0.00 sec)
mysql> show indexes from coef;
+-------+------------+-------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+-------+------------+-------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| coef | 0 | PRIMARY | 1 | id | A | 9078 | NULL | NULL | | BTREE | |
| coef | 1 | spread_ticker_idx | 1 | id_spread | A | NULL | NULL | NULL | YES | BTREE | |
| coef | 1 | spread_ticker_idx | 2 | id_ticker | A | NULL | NULL | NULL | YES | BTREE | |
+-------+------------+-------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
3 rows in set (0.00 sec)
mysql> show indexes from tickers;
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| tickers | 0 | PRIMARY | 1 | id | A | 100 | NULL | NULL | | BTREE | |
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
1 row in set (0.00 sec)
mysql> show indexes from prices;
+--------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+--------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| prices | 0 | PRIMARY | 1 | id | A | 19962 | NULL | NULL | | BTREE | |
| prices | 1 | id_ticker | 1 | id_ticker | A | 19962 | NULL | NULL | | BTREE | |
+--------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
2 rows in set (0.15 sec)
And this is the explain of the query:
+----+-------------+------------+--------+-------------------+-------------------+---------+---------------------------+--------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+------------+--------+-------------------+-------------------+---------+---------------------------+--------+-------------+
| 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 500 | |
| 1 | PRIMARY | c | ref | spread_ticker_idx | spread_ticker_idx | 5 | s.id | 90 | Using where |
| 1 | PRIMARY | t | eq_ref | PRIMARY | PRIMARY | 4 | spreadtrading.c.id_ticker | 1 | Using where |
| 1 | PRIMARY | <derived3> | ALL | NULL | NULL | NULL | NULL | 100 | |
| 3 | DERIVED | prices | index | NULL | id_ticker | 4 | NULL | 119774 | |
| 2 | DERIVED | spreads | ref | check_idx | check_idx | 5 | | 2298 | Using where |
+----+-------------+------------+--------+-------------------+-------------------+---------+---------------------------+--------+-------------+
6 rows in set (0.27 sec)
Could I optimize it?
Thank you!
EDIT:
I would like to know if the INDEXES and the table's structure are optimized for the query I posted above. The results that I get using this query are good, it works well, but maybe I can optimize it to increse the "speed" of the query.

I think you may gain something by dropping the spreads subquery and moving the WHERE clause to the end, as in the following code. This loses your LIMIT restriction - perhaps you could put a LIMIT clause at the end as well, depending on what you're trying to achieve in terms of limiting the size of the output.
SELECT
s.last_spread, s.sd, s.mean, s.id
,c.id_ticker, c.coef
,t.ticker
,p.last, p.price
FROM spreads as s
INNER JOIN coef as c
ON c.id_spread = s.id
INNER JOIN tickers AS t
ON t.id = c.id_ticker
LEFT JOIN (SELECT prices.id_ticker, MAX(prices.date) as last, prices.price FROM prices GROUP BY prices.id_ticker) AS p
ON p.id_ticker = t.id
WHERE s.id_check = 1

Why doesn't mysql use my index?

I have two tables:
mysql> desc myps3t_gameusertrophyinfo;
+-----------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| user_id | int(11) | NO | MUL | NULL | |
| trophy_id | int(11) | NO | MUL | NULL | |
| date | datetime | NO | MUL | NULL | |
| date_read | varchar(100) | NO | | NULL | |
+-----------+--------------+------+-----+---------+----------------+
5 rows in set (0.19 sec)
mysql> show index from myps3t_gameusertrophyinfo;
+---------------------------+------------+------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+---------------------------+------------+------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| myps3t_gameusertrophyinfo | 0 | PRIMARY | 1 | id | A | 4004589 | NULL | NULL | | BTREE | |
| myps3t_gameusertrophyinfo | 0 | user_id | 1 | user_id | A | 7686 | NULL | NULL | | BTREE | |
| myps3t_gameusertrophyinfo | 0 | user_id | 2 | trophy_id | A | 4004589 | NULL | NULL | | BTREE | |
| myps3t_gameusertrophyinfo | 1 | myps3t_gameusertrophyinfo_403f60f | 1 | user_id | A | 7686 | NULL | NULL | | BTREE | |
| myps3t_gameusertrophyinfo | 1 | myps3t_gameusertrophyinfo_61a683d8 | 1 | trophy_id | A | 22624 | NULL | NULL | | BTREE | |
| myps3t_gameusertrophyinfo | 1 | idx_gameusertrophyinfo_date | 1 | date | A | 4004589 | NULL | NULL | | BTREE | |
+---------------------------+------------+------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
7 rows in set (0.06 sec)
the other table:
mysql> desc myps3t_gametrophyinfo ;
+-----------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| game_id | int(11) | NO | MUL | NULL | |
| name | varchar(500) | NO | | NULL | |
| desc | varchar(500) | NO | | NULL | |
| type | varchar(20) | NO | | NULL | |
| pic_url | varchar(200) | NO | | NULL | |
| desc_pt | varchar(500) | NO | | NULL | |
| name_pt | varchar(500) | NO | | NULL | |
| hidden_id | int(11) | NO | | NULL | |
| total_id | int(11) | NO | | NULL | |
| trophy_id | int(11) | NO | | NULL | |
| addon_id | int(11) | YES | | NULL | |
| points | double | NO | | 0 | |
| sony_id | int(11) | YES | | NULL | |
+-----------+--------------+------+-----+---------+----------------+
14 rows in set (0.00 sec)
mysql> show index from myps3t_gametrophyinfo;
+-----------------------+------------+-------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+-----------------------+------------+-------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| myps3t_gametrophyinfo | 0 | PRIMARY | 1 | id | A | 25976 | NULL | NULL | | BTREE | |
| myps3t_gametrophyinfo | 1 | myps3t_gametrophyinfo_game_id | 1 | game_id | A | 764 | NULL | NULL | | BTREE | |
+-----------------------+------------+-------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
when i do this query:
mysql> explain select * from myps3t_gameusertrophyinfo a, myps3t_gametrophyinfo b where a.trophy_id = b.id and b.addon_id = 58; +----+-------------+-------+--------+--------------------------------------------------------------+---------+---------+-----------------------------+---------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+--------+--------------------------------------------------------------+---------+---------+-----------------------------+---------+-------------+
| 1 | SIMPLE | a | ALL | myps3t_gameusertrophyinfo_61a683d8,myps3t_gameusertrophyinfo | NULL | NULL | NULL | 4004592 | |
| 1 | SIMPLE | b | eq_ref | PRIMARY | PRIMARY | 4 | fabriciols_ps3t.a.trophy_id | 1 | Using where |
+----+-------------+-------+--------+--------------------------------------------------------------+---------+---------+-----------------------------+---------+-------------+
2 rows in set (0.00 sec)
why mysql do not use my keys ?
this query take more than 30 seconds, the first table has 4milion records ...
-- edit --
for quasnoi
mysql> SELECT COUNT(*), COUNT(DISTINCT addon_id), SUM(addon_id = 58) FROM myps3t_gametrophyinfo;
+----------+--------------------------+--------------------+
| COUNT(*) | COUNT(DISTINCT addon_id) | SUM(addon_id = 58) |
+----------+--------------------------+--------------------+
| 25976 | 160 | 6 |
+----------+--------------------------+--------------------+
1 row in set (0.00 sec)

MySQL chooses a as a leading table and b as a driven table. It does use a PRIMARY KEY on b for the joins.
Create an index on myps3t_gametrophyinfo (addon_id), this way b will be more probably chosen as a leading table.

You can try
select * from
myps3t_gametrophyinfo b
STRAIGHT_JOIN myps3t_gameusertrophyinfo a ON (a.trophy_id = b.id)
WHERE b.addon_id = 58;

I would probably rewrite the query to try to get a more sane execution path. I think something like below is more likely to get you the performance you want and is more clear in what you are doing to a human reader
SELECT * FROM myps3t_gametrophyinfo a LEFT JOIN myps3t_gameusertrophyinfo b ON a.id = b.trophy_id WHERE a.addon_id=58;