[Solved] SQL query finding maximum for two joint tables by category

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:

  1. Description of the steps you can take to speed up the query.
  2. The optimal indexes for this query, which you can copy and create in your database.
  3. An automatically re-written query you can copy and execute in your database.
The optimization process and recommendations:
  1. Avoid Using Date Functions In Conditions (query line: 13): When a function is used directly on an indexed column, the database's optimizer won’t be able to use the index. An alternative way is to use a range condition instead of a function call.
  2. Explicitly ORDER BY After GROUP BY (modified query below): By default, the database sorts all 'GROUP BY col1, col2, ...' queries as if you specified 'ORDER BY col1, col2, ...' in the query as well. If a query includes a GROUP BY clause but you want to avoid the overhead of sorting the result, you can suppress sorting by specifying 'ORDER BY NULL'.
The optimized query:
SELECT
        DISTINCT cuisine,
        name,
        address,
        max(totalscore) 
    FROM
        restaurant r 
    JOIN
        inspection i 
            ON r.rid = i.rid 
    WHERE
        county = 'Cobb' 
        AND idate BETWEEN '2015-01-01 00:00:00' AND '2015-12-31 23:59:59' 
    GROUP BY
        cuisine,
        name,
        adddress 
    ORDER BY
        NULL

Related Articles



* original question posted on StackOverflow here.