MySQL 8.0: Unexpected Behavior with JSON_ARRAYAGG() in Aggregation Queries
I'm following best practices but I've been struggling with this for a few days now and could really use some help. I just started working with I'm working on a project and hit a roadblock. I'm experiencing unexpected results when using the `JSON_ARRAYAGG()` function in MySQL 8.0 with a complex aggregation query. My goal is to aggregate user activity records into a JSON array, but the output seems to be duplicating entries for certain user IDs. Here's the relevant query I'm using: ```sql SELECT user_id, JSON_ARRAYAGG(activity) AS activities FROM user_activities WHERE activity_date >= '2023-01-01' GROUP BY user_id; ``` I've verified that there are no duplicate rows in the `user_activities` table for the same `user_id` and `activity`. However, when I run this query, I get results like the following: ``` user_id | activities -------- | ------------------------------------------------- 1 | [{"activity":"login"}, {"activity":"login"}] 2 | [{"activity":"purchase"}] 3 | [{"activity":"logout"}, {"activity":"logout"}] ``` Notice how user ID 1 has the `login` activity duplicated, and user ID 3 has the `logout` activity duplicated. I've also tried adding `DISTINCT` to the `JSON_ARRAYAGG()` function as below: ```sql SELECT user_id, JSON_ARRAYAGG(DISTINCT activity) AS activities FROM user_activities WHERE activity_date >= '2023-01-01' GROUP BY user_id; ``` However, this still does not resolve the duplication issue. I suspect it might be related to how the aggregation is being executed in conjunction with the grouping, but I haven't been able to pinpoint the exact cause. Is there a known issue with `JSON_ARRAYAGG()` in MySQL 8.0 that could lead to such behavior, or am I missing something in my query structure? Any insights or suggestions would be greatly appreciated! My development environment is Ubuntu. I'd really appreciate any guidance on this. My team is using Sql for this microservice. Thanks for any help you can provide! This is my first time working with Sql stable. Cheers for any assistance! This issue appeared after updating to Sql 3.9.