Question

Here is the SQL query in question:

select *  from company1 
left join company2 on company2.model 
    LIKE CONCAT(company1.model,'%') 
    where company1.manufacturer = company2.manufacturer

company1 contains 2000 rows while company2 contains 9000 rows.

The query takes around 25 seconds to complete.

I have company1.model and company2.model indexed.

Any idea how I can speed this up? Thanks!

+----+-------------+-----------+------+---------------+------+---------+------+------+--------------------------------+
| id | select_type | table     | type | possible_keys | key  | key_len | ref  | rows | Extra                          |
+----+-------------+-----------+------+---------------+------+---------+------+------+--------------------------------+
|  1 | SIMPLE      | company1  | ALL  | NULL          | NULL | NULL    | NULL | 2853 |                                |
|  1 | SIMPLE      | company2  | ALL  | NULL          | NULL | NULL    | NULL | 8986 | Using where; Using join buffer |
+----+-------------+-------+---+------+---------------+------+---------+------+------+--------------------------------+

Answer 1

This query is not conceptually identical to yours, but maybe you want something like this? I am quite sure it will give you the same result as yours:

select
  *
from
  company1 inner join company2
  on company1.manufacturer = company2.manufacturer
where
  company2.model LIKE CONCAT(company1.model,'%')

EDIT: i also removed your left join and put an inner join. If the join doesn’t succeed, company2.model is always null and NULL LIKE 'Something%' can never be true.