[Solved] Number of users that logged in at least once in past 7 days, day by day

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 Calling Functions With Indexed Columns (query line: 9): When a function is used directly on an indexed column, the database's optimizer won’t be able to use the index. For example, if the column `date1` is indexed, the index won’t be used as it’s wrapped with the function `DATE_SUB`. If you can’t find an alternative condition that won’t use a function call, a possible solution is to store the required value in a new indexed column.
  2. Avoid Calling Functions With Indexed Columns (query line: 10): When a function is used directly on an indexed column, the database's optimizer won’t be able to use the index. For example, if the column `date1` is indexed, the index won’t be used as it’s wrapped with the function `DATE_ADD`. If you can’t find an alternative condition that won’t use a function call, a possible solution is to store the required value in a new indexed column.
The optimized query:
SELECT
        DISTINCT (DATE_FORMAT(crm_login_info.`login_time`,
        '%Y-%m-%d')) AS date1,
        (SELECT
            COUNT(DISTINCT crm_login_info.`user_id`) 
        FROM
            crm_login_info 
        WHERE
            crm_login_info.`login_time` > DATE_SUB(date1, INTERVAL 6 DAY) 
            AND crm_login_info.`login_time` <= DATE_ADD(date1, INTERVAL 1 DAY)) AS distinct1 
    FROM
        crm_login_info 
    ORDER BY
        date1 ASC

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* original question posted on StackOverflow here.