What is the best way to handle a join / group_concat query in MySQL I am looking for some feedback regarding the best way to handle the following (simplified for this example) situation.
I have 3 tables: tasks, assignees, and users
---tasks----
id, task, completed

---assignees----
user_id, task_id

---users---
id, name

I need to select tasks with concatenated user names of assignees, like so
tasks.task  |   assigned_names.names   
---------------------------------------
&quot;My task&quot;   |   &quot;Joe Schmoe, Bob Mcbart, Sally McGuire&quot;

Here is what I have currently
SELECT tasks.task, assigned_names.names

FROM tasks

LEFT JOIN (
   SELECT 
      GROUP_CONCAT( users.name SEPARATOR ',' ) AS names,
      assignees.task_id
      FROM assignees
      LEFT JOIN users ON users.id = assignees.user_id
      GROUP BY assignees.task_id
   
) assigned_names ON assigned_names.task_id = tasks.id

WHERE tasks.completed IS NULL

My main concern is that the assignees table has hundreds of thousands of records, and doing a group on the whole table every time seems like not a good idea.
Is there a better strategy?
Also, I would be happy to rephrase my question title if someone could suggest better language.
Thanks!
Simplicity is beautify. Multiple JOINs are allowed. There is no need to the JOINs to be LEFT JOINS as you want data that maches always.
SELECT tasks.task, GROUP_CONCAT( users.name SEPARATOR ',' ) AS names,
FROM assignees
JOIN tasks ON assignees.task_id = tasks.id
JOIN users ON assignees.user_id = users.id
WHERE tasks.completed IS NULL
GROUP BY assignees.task_id