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:
- Avoid Selecting Unnecessary Columns (query line: 2): Avoid selecting all columns with the '*' wildcard, unless you intend to use them all. Selecting redundant columns may result in unnecessary performance degradation.
- Create Optimal Indexes (modified query below): The recommended indexes are an integral part of this optimization effort and should be created before testing the execution duration of the optimized query.
- Prefer Inner Join Over Left Join (modified query below): We identified that one or more left joined entities (e.g. `cat_meta`) are used in the 'where' clause, in a way that allows to replace it with an optimized inner join. Inner joins can be fully optimized by the database, while Left joins apply limitations on the database's optimizer.
Optimal indexes for this query:
ALTER TABLE `cat_meta` ADD INDEX `cat_meta_idx_meta_key_meta_value` (`meta_key`,`meta_value`);
ALTER TABLE `categories` ADD INDEX `categories_idx_cat_id` (`cat_id`);
The optimized query:
SELECT
*
FROM
categories
INNER JOIN
cat_meta
ON cat_meta.cat_id = categories.cat_id
WHERE
cat_meta.meta_key = 'Delete'
AND cat_meta.meta_value <> 1