MySQL 8.0: Issues with Indexing Large JSON Fields Leading to Slow Queries
Quick question that's been bugging me - I'm encountering significant performance issues when querying large JSON fields in MySQL 8.0. I've created a table with a JSON column that stores user data as follows: ```sql CREATE TABLE users ( id INT AUTO_INCREMENT PRIMARY KEY, user_data JSON, created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ); ``` The `user_data` column can store a lot of information, sometimes exceeding 10KB per entry. I'm trying to optimize my queries, and I thought adding a functional index would help. I created the index like this: ```sql CREATE INDEX idx_user_name ON users((user_data->>'$.name')); ``` However, I'm still experiencing performance issues. For instance, this query: ```sql SELECT * FROM users WHERE user_data->>'$.name' = 'John Doe'; ``` takes several seconds to execute, even when the table contains only a few thousand records. I've analyzed the `EXPLAIN` plan, and it seems like the query is doing a full table scan despite the index. The output of the `EXPLAIN` looks like this: ``` +----+-------------+-------+------+---------------+---------+---------+------+------+----------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+-------+------+---------------+---------+---------+------+------+----------+-------------+ | 1 | SIMPLE | users | ALL | idx_user_name | NULL | NULL | NULL | 5000 | 100.00 | Using where | +----+-------------+-------+------+---------------+---------+---------+------+------+----------+-------------+ ``` I also tried tweaking some configuration parameters for MySQL, such as `innodb_buffer_pool_size`, but that didn't seem to have much impact on the performance. Is there a better way to structure my data or index the JSON fields to improve query performance? Are there specific best practices for working with large JSON columns in MySQL that I should consider? Any insights would be greatly appreciated! I'm working on a CLI tool that needs to handle this. I'm coming from a different tech stack and learning Sql.