Question

EXPLAIN SELECT * 
FROM (
`phppos_items`
)
WHERE (
name LIKE  'AB10LA2%'
OR item_number LIKE  'AB10LA2%'
OR category LIKE  'AB10LA2%'
)
AND deleted =0
ORDER BY  `name` ASC 
LIMIT 16

+----+-------------+--------------+-------+-----------------------------------+------+---------+------+------+-------------+
| id | select_type | table        | type  | possible_keys                     | key  | key_len | ref  | rows | Extra       |
+----+-------------+--------------+-------+-----------------------------------+------+---------+------+------+-------------+
|  1 | SIMPLE      | phppos_items | index | item_number,name,category,deleted | name | 257     | NULL |   32 | Using where |
+----+-------------+--------------+-------+-----------------------------------+------+---------+------+------+-------------+

This query takes 9 seconds to run (the table has 1 million + rows).

I have an index on item_number,name,category,deleted separately. How can I speed up this query?

Answer 1

Best I’m aware, MySQL doesn’t know how to perform bitmap OR index scans. But you could rewrite it as the union of three queries to force it to do such a thing, if you’ve an index on each field. If so, this will be very fast:

select *
from (
  select * from (
           select *
           from phppos_items
           where name like 'AB10LA2%' and deleted = 0
           order by `name` limit 16
           ) t
  union
  select * from (
           select *
           from phppos_items
           where item_number like 'AB10LA2%' and deleted = 0
           order by `name` limit 16
           ) t
  union
  select * from (
           select *
           from phppos_items
           where category like 'AB10LA2%' and deleted = 0
           order by `name` limit 16
           ) t
  ) as top rows
order by `name` limit 16