Step-by-step guide to monitor MySQL slow queries performance. Track slow query count, execution times, and identify performance bottlenecks with automated monitoring.

Last updated: 2026-01-11

How to Monitor MySQL Slow Queries Performance

Monitor MySQL slow queries to identify performance bottlenecks and optimize database operations. This guide shows you how to track slow query count, execution times, and set up automated monitoring with Zuzia.app.

For comprehensive database monitoring, see Database Performance Monitoring. For troubleshooting database issues, see Database Connection Timeout Errors.

Why Monitor MySQL Slow Queries

Slow queries can cause application timeouts, poor user experience, and database performance degradation. Monitoring slow queries helps you identify performance bottlenecks, optimize database operations, and prevent issues before they impact users.

Method 1: Enable MySQL Slow Query Log

Enable Slow Query Logging

# Connect to MySQL
mysql -u root -p

# Enable slow query log
SET GLOBAL slow_query_log = 'ON';

# Set slow query threshold (queries taking longer than 2 seconds)
SET GLOBAL long_query_time = 2;

# Verify slow query log is enabled
SHOW VARIABLES LIKE 'slow_query_log';
SHOW VARIABLES LIKE 'long_query_time';

Check Slow Query Log Location

# Find slow query log file location
mysql -u root -p -e "SHOW VARIABLES LIKE 'slow_query_log_file';"

# View slow query log
sudo tail -f /var/log/mysql/slow-query.log

Method 2: Monitor Slow Queries from MySQL

Check Slow Query Count

# Check total slow queries
mysql -u root -p -e "SHOW STATUS LIKE 'Slow_queries';"

# Check slow queries per hour
mysql -u root -p -e "SHOW STATUS LIKE 'Slow_queries';" | grep -o '[0-9]*'

View Recent Slow Queries

# View slow queries from slow log table (if enabled)
mysql -u root -p -e "SELECT * FROM mysql.slow_log ORDER BY start_time DESC LIMIT 10;"

Analyze Slow Query Patterns

# Count slow queries by user
mysql -u root -p -e "SELECT user_host, COUNT(*) as slow_count FROM mysql.slow_log GROUP BY user_host ORDER BY slow_count DESC;"

# Find most frequent slow queries
mysql -u root -p -e "SELECT sql_text, COUNT(*) as count FROM mysql.slow_log GROUP BY sql_text ORDER BY count DESC LIMIT 10;"

Method 3: Automated Slow Query Monitoring with Zuzia.app

Set up automated monitoring to track slow queries continuously and receive alerts when slow query count exceeds thresholds.

Step 1: Add Slow Query Monitoring Command

Log in to Zuzia.app Dashboard
- Access your Zuzia.app account
- Navigate to your server
- Click "Add Scheduled Task"
Configure Slow Query Check Command
```
mysql -u root -pPASSWORD -e "SHOW STATUS LIKE 'Slow_queries';" | grep -o '[0-9]*'
```
- Replace PASSWORD with your MySQL root password
- Set execution frequency (every 5-10 minutes)
- Configure alerts when slow query count increases

Step 2: Configure Alert Thresholds

Warning: Slow query count increases by 10+ in an hour
Critical: Slow query count increases by 50+ in an hour
Emergency: Slow query count increases by 100+ in an hour

Step 3: Monitor Slow Query Log

Add command to check slow query log size:

# Check slow query log size
du -h /var/log/mysql/slow-query.log

# Count lines in slow query log
wc -l /var/log/mysql/slow-query.log

Best Practices for Slow Query Monitoring

1. Set Appropriate Thresholds

Set long_query_time based on your application requirements
Typical values: 1-2 seconds for web applications
Lower thresholds (0.5 seconds) for high-performance applications

2. Review Slow Queries Regularly

Review slow query log weekly
Identify patterns in slow queries
Optimize frequently slow queries
Add indexes where needed

3. Monitor Slow Query Trends

Track slow query count over time
Identify peak times for slow queries
Correlate slow queries with application activity
Plan optimizations based on trends

4. Optimize Slow Queries

Add indexes to frequently queried columns
Rewrite inefficient queries
Use query caching where appropriate
Optimize database schema if needed

Troubleshooting High Slow Query Count

Step 1: Identify Problematic Queries

# View recent slow queries
sudo tail -100 /var/log/mysql/slow-query.log

# Find most frequent slow queries
mysql -u root -p -e "SELECT sql_text, COUNT(*) as count FROM mysql.slow_log GROUP BY sql_text ORDER BY count DESC LIMIT 10;"

Step 2: Analyze Query Performance

# Explain slow query execution plan
mysql -u root -p -e "EXPLAIN SELECT ... FROM ... WHERE ...;"

# Check table indexes
mysql -u root -p -e "SHOW INDEXES FROM table_name;"

Step 3: Optimize Queries

Add missing indexes
Rewrite inefficient queries
Use appropriate JOIN types
Limit result sets when possible

FAQ: Common Questions About MySQL Slow Query Monitoring

What is considered a slow query?

Slow queries depend on your application requirements. Generally, queries taking longer than 1-2 seconds are considered slow. Set long_query_time based on your performance requirements.

How often should I check slow queries?

For production databases, continuous automated monitoring is essential. Zuzia.app can check slow query count every few minutes, alerting you when slow queries increase significantly.

Can slow queries impact server performance?

Yes, slow queries can consume excessive CPU and memory, block other queries, and cause database performance degradation. Monitor and optimize slow queries proactively.

How do I optimize slow queries?

Optimize slow queries by adding indexes to frequently queried columns, rewriting inefficient queries, using query caching, and optimizing database schema based on query patterns.

How to Monitor MySQL Slow Queries Performance