Fix MySQL EXPLAIN Filtered Issues

In MySQL, the EXPLAIN statement is used to analyze the execution plan of a query, providing useful information about the query. The “filtered” field is used to indicate the percentage of rows in the query result set compared to the total number of rows.

If the filtered value returned by the EXPLAIN statement is low, it indicates that there are a high number of rows in the query result set, which may lead to performance issues. This could be due to inappropriate query conditions or a lack of proper indexing.

To address this issue, you could consider the following points:

1. Optimize query conditions by analyzing the query statement to ensure proper indexes are used and the query conditions are optimizable. You can restrict the result set size by using WHERE and JOIN conditions, or reduce the number of rows by breaking down complex queries into simpler ones.
2. Create appropriate indexes: Create suitable indexes based on the needs of the query statement to speed up query performance. Use the EXPLAIN statement to see if indexes are being used and further optimize them.
3. Optimize table structure by modifying it to meet the requirements of queries. This can involve splitting a large table into smaller ones or defining appropriate data types and lengths for fields.
4. Consider using caching: If the query results are relatively stable, it is worth considering using caching to improve query performance. MySQL offers a query caching feature that can be enabled by setting appropriate parameters.

In conclusion, by analyzing the EXPLAIN results and optimizing the query statements and table structure, the issue of EXPLAIN filtered in MySQL can be resolved, ultimately improving query performance.