👀 Views: 87 💬 Answers: 1 📅 Created: 2025-07-22

mysql json performance sql

I tried several approaches but none seem to work... I'm encountering significant performance issues when running a query that utilizes JSON functions in the WHERE clause on MySQL 8.0. The database has a table `users` with a JSON column `profile_data` that stores various user attributes. The goal is to filter users based on the value of a specific key within the JSON object, but the query takes an inordinate amount of time to execute, especially as the dataset grows. Here's the query I'm using: ```sql SELECT * FROM users WHERE JSON_UNQUOTE(JSON_EXTRACT(profile_data, '$.age')) > 25; ``` I've indexed the `profile_data` column using a generated column: ```sql ALTER TABLE users ADD age INT GENERATED ALWAYS AS (JSON_UNQUOTE(JSON_EXTRACT(profile_data, '$.age'))) STORED; CREATE INDEX idx_age ON users(age); ``` However, even with the index in place, the performance isn't improving as expected. I’ve tried running `ANALYZE TABLE users;` to update statistics, but it hasn’t made a noticeable difference. Additionally, I've checked the query execution plan using `EXPLAIN` and noticed that it still performs a full table scan, which is concerning. The execution plan shows: ``` +----+-------------+-------+-------+-------------------+---------+---------+------+------+----------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+-------+-------+-------------------+---------+---------+------+------+----------+-------------+ | 1 | SIMPLE | users | ALL | idx_age | NULL | NULL | NULL | 50000| 100.00 | Using where | +----+-------------+-------+-------+-------------------+---------+---------+------+------+----------+-------------+ ``` I’m wondering if there are better practices for querying JSON data in MySQL or if I’ve overlooked an important aspect of indexing. Any insights on improving query performance would be greatly appreciated! I'm coming from a different tech stack and learning Sql. Is this even possible?