Must-Know MySQL Performance Metrics

Highlights: Mysql Performance Metrics

  • 1. Queries per second (QPS)
  • 2. Slow queries
  • 3. Threads connected
  • 4. Threads running
  • 5. InnoDB buffer pool hit rate
  • 6. InnoDB row lock time
  • 7. InnoDB row lock waits
  • 8. Table lock contention
  • 9. Temporary tables created on disk
  • 10. Sort_merge_passes
  • 11. Select_full_join
  • 12. Filtered
  • 13. Key_read_requests
  • 14. Key_reads
  • 15. Key_write_requests
  • 16. Key_writes

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In today’s data-driven world, the efficiency and reliability of database systems are more crucial than ever. As organizations continue to rely on vast amounts of information for decision-making processes, ensuring optimal performance levels of databases becomes a top priority. MySQL, one of the most popular and widely-used open-source relational database management systems, plays a significant role in the management of mission-critical data. In this blog post, we will delve into the essential MySQL performance metrics that every database administrator, developer, and stakeholder should be aware of in order to proactively monitor, optimize, and maintain the performance of their databases.

MySQL Performance Metrics You Should Know

1. Queries per second (QPS)

The number of queries executed per second by the MySQL server. This metric helps to understand the overall load on the server and can be used to optimize the server settings or application queries.

2. Slow queries

The number of queries that take longer than a predefined time threshold (usually set to 1-2 seconds) to execute. Slow queries can cause performance issues and should be investigated for optimization.

3. Threads connected

The number of connections (threads) established with the MySQL server. A high number of connections can lead to resource contention, impacting overall performance.

4. Threads running

The number of threads actively executing queries or waiting for resources (such as locks) to be available. Monitoring this metric can help identify bottlenecks in the server.

5. InnoDB buffer pool hit rate

The percentage of pages read from the InnoDB buffer pool compared to total pages requested. A high buffer pool hit rate indicates efficient memory management, reducing the need for disk I/O operations.

6. InnoDB row lock time

The average time taken to acquire a row-level lock in InnoDB tables. If this value is high, it indicates locking contention and may require query optimization.

7. InnoDB row lock waits

The number of times a row-level lock had to be waited for. High values may indicate high levels of contention and potential performance issues.

8. Table lock contention

The percentage of table lock requests that require waiting due to other threads holding the lock. High contention can lead to query delays and performance issues.

9. Temporary tables created on disk

The number of temporary tables created on disk rather than in memory. This can cause slower query execution, as disk operations are typically slower than memory operations.

10. Sort_merge_passes

The number of merge passes required to perform a sort operation. A high value may indicate a need to increase the sort_buffer_size or optimize queries.

11. Select_full_join

The number of joins that perform table scans due to missing indexes. High values may indicate a need for better indexing or query optimization.

12. Filtered

The percentage of rows that are filtered by where and having clauses in SELECT statements. Lower values may indicate inefficient filtering, resulting in slow query execution.

13. Key_read_requests

The number of requests made to read a key block from the MyISAM key cache. Monitoring this metric can help identify performance issues related to key cache misses.

14. Key_reads

The number of key blocks actually read from the MyISAM key cache. Comparing key_reads to key_read_requests can help identify key cache efficiency.

15. Key_write_requests

The number of requests made to write a key block to the MyISAM key cache. Monitoring this metric helps identify potential write contention issues.

16. Key_writes

The number of key blocks actually written to the MyISAM key cache. Comparing key_writes to key_write_requests can help identify key cache efficiency during write operations.

Mysql Performance Metrics Explained

MySQL performance metrics are crucial in evaluating the efficiency and overall health of a server. Queries per second (QPS) provides insight into server load, helping to determine optimizations needed for both application queries and server settings. Slow queries, threads connected, and threads running contribute to identifying performance issues and bottlenecks within the system. Monitoring InnoDB metrics like the buffer pool hit rate, row lock time, and row lock waits can lead to better memory management and identify opportunities for query optimization. Table lock contention, temporary tables created on disk, and sort_merge_passes highlight areas that may need adjustments in sort buffer size, query optimization, or indexing.

Metrics like select_full_join, filtered, and key-related metrics such as key_read_requests, key_reads, key_write_requests, and key_writes are essential in evaluating the effectiveness of filtering, indexing, caching, and potential write contention. Understanding these metrics allows for improved server performance and optimal query execution, ensuring a robust and efficient MySQL database environment.


In conclusion, MySQL performance metrics are crucial in understanding the overall efficiency and health of your database systems. Through proper monitoring, evaluation, and optimization of these metrics, you can dramatically improve the responsiveness, reliability, and scalability of your applications. Remember, it’s essential to prioritize metrics based on the impact they have on the performance of your MySQL server, while continuously seeking to identify and rectify bottlenecks that may arise. By staying informed about these vital indicators, database administrators (DBAs) and developers can work together to create high-performance systems that meet the ever-evolving demands of the modern digital landscape.


What are the key MySQL Performance Metrics that should be monitored?

The key MySQL Performance Metrics to monitor include query performance, slow queries, connection statistics, buffer pool usage, and table cache hit rate.

How can you optimize query performance in MySQL?

Query performance can be optimized in MySQL by using indexes effectively, ensuring proper database design, using the EXPLAIN statement to analyze query plans, limiting large result sets with pagination, and rewriitng subqueries as JOINs when possible.

What can cause slow queries in MySQL and how can you identify them?

Slow queries in MySQL can be caused by insufficient indexes, poorly written queries, inefficient database design, or insufficient server resources. To identify them, enable the slow query log and use the 'mysqldumpslow' tool to view and analyze the log.

Why are MySQL connection statistics important for monitoring performance?

MySQL connection statistics are vital for monitoring performance as they provide insights into the number of users connecting to the server, the time taken for these connections to be executed or processed, and potential bottlenecks, which helps in identifying issues and improving database performance.

How can you improve buffer pool usage in MySQL?

To improve buffer pool usage in MySQL, consider increasing the size of the buffer pool, using multiple buffer pool instances, monitoring the buffer pool hit rate, and configuring InnoDB read-ahead settings to reduce I/O overhead.

How we write our statistic reports:

We have not conducted any studies ourselves. Our article provides a summary of all the statistics and studies available at the time of writing. We are solely presenting a summary, not expressing our own opinion. We have collected all statistics within our internal database. In some cases, we use Artificial Intelligence for formulating the statistics. The articles are updated regularly.

See our Editorial Process.

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