How to optimize this SQL query?
In case you have your own slow SQL query, you can optimize it automatically here.
For the query above, the following recommendations will be helpful as part of the SQL tuning process.
You'll find 3 sections below:
- Description of the steps you can take to speed up the query.
- The optimal indexes for this query, which you can copy and create in your database.
- An automatically re-written query you can copy and execute in your database.
The optimization process and recommendations:
- Prefer Direct Join Over Joined Subquery (query line: 21): We advise against using subqueries as they are not optimized well by the optimizer. Therefore, we recommend to replace subqueries with JOIN clauses.
- Use Numeric Column Types For Numeric Values (query line: 25): Referencing a numeric value (e.g. 2) as a string in a WHERE clause might result in poor performance. Possible impacts of storing numbers as varchars: more space will be used, you won't be able to perform arithmetic operations, the data won't be self-validated, aggregation functions like SUM won't work, the output may sort incorrectly and more. If the column is numeric, remove the quotes from the constant value, to make sure a numeric comparison is done.
- Use Numeric Column Types For Numeric Values (query line: 26): Referencing a numeric value (e.g. 0) as a string in a WHERE clause might result in poor performance. Possible impacts of storing numbers as varchars: more space will be used, you won't be able to perform arithmetic operations, the data won't be self-validated, aggregation functions like SUM won't work, the output may sort incorrectly and more. If the column is numeric, remove the quotes from the constant value, to make sure a numeric comparison is done.
The optimized query:
SELECT
machine_laptop,
machine_name,
B.id AS m_id,
C.id AS c_id,
C.confirmed AS c_confirmed,
C.live AS c_live,
B.start_time AS b_start_time,
(C.id IS NOT NULL
AND C.confirmed != 2
AND C.live != 0) AS booked
FROM
event_information A
INNER JOIN
event_machine_time B
ON (
1 = 1
)
LEFT JOIN
event_booking AS C
ON (
B.id = C.machine_time_id
AND A.id = C.information_id
)
AND C.confirmed <> '2'
AND C.live <> '0'
WHERE
A.id = :id
GROUP BY
m_id
ORDER BY
machine_name ASC,
b_start_time ASC