Database Design for Follow Users Feature with Large Scale

Asked Jan 08 '20 at 23:52

Active Jan 09 '20 at 00:29

Viewed 106 times

I’m trying to come up with a MySQL database schema to support a feature to store users following other users. I see two approaches:

1st approach) have a users_following table with two columns: user_id and follower_id. Problem I see with this approach is for popular users with many followers, it would create many records in the table.

Alternative approach) have the users_following to store user_id and follower_ids, where the follower_ids store the followers id in a list (comma separated).

Is there any problem with the alternative approach above?

UPDATE: For this feature, I do not need to query by the individual followers. The way this table will be used is the app will query for the user, then grab the followers and run some logic to it.

edited Jan 09 '20 at 00:29

asked Jan 08 '20 at 23:52

user2345093

3

Warmly recommended reading: [Is storing a delimited list in a database column really that bad?](https://stackoverflow.com/q/3653462/10676716) – GMB Jan 08 '20 at 23:54
@GMB Thanks, I will read it. There’s a part I should’ve included in the question: I do not need to query for the individual followers. Updated the question. – user2345093 Jan 09 '20 at 00:30
Suppose a user is deleted. You'd have to reevaluate **all** the lists. (similar for duplicates or updates) – wildplasser Jan 09 '20 at 00:46
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The alternative idea is a terrible one – Strawberry Jan 09 '20 at 00:48
@Strawberry Could you elaborate on why? Thanks in advance. – user2345093 Jan 09 '20 at 04:16
Because it violates 3NF. – Strawberry Jan 09 '20 at 08:15
1

In addition to what Strawberry has said, there is also the fact that a comma separated list is likely to take MORE storage if your id values are normally 4 byte integers. – Uueerdo Jan 09 '20 at 17:28
Approach 1 is the way to go. – Nic3500 Jan 11 '20 at 01:45

Database Design for Follow Users Feature with Large Scale

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