adminMySQL Memory Buffer Tuning Mental Model Checklist
MySQL uses memory for buffers, caches, connections and temporary operations. Tuning memory without understanding the server workload can cause instability, swap usage or crashes.
Core principle
MySQL memory is part of total server memory. WordPress, PHP-FPM, Nginx, Docker and backup jobs all compete with MySQL for RAM.
Checklist
- Check total RAM.
- Check current memory and swap usage.
- Check whether MySQL is a top memory process.
- Identify other memory-heavy services.
- Check current buffer-related settings.
- Check connection count and max connections.
- Avoid copying tuning templates blindly.
- Change memory settings conservatively.
- Restart and monitor after change.
- Document memory assumptions.
Reusable lesson
This applies to WordPress VPS, MySQL high load, PHP-FPM tuning, database-heavy plugins, imports, dashboards and reporting systems.
When to Use This Checklist
Use this checklist when MySQL uses too much memory, the VPS swaps, database queries slow down or tuning is needed for small servers.
Required Tools
SSH access, MySQL admin access, top, free, MySQL variables, service list, monitoring data
Before You Start
Do not increase MySQL buffers without checking total RAM and memory used by PHP-FPM, Docker and other services.
Structured Checklist Steps
- Check total RAM.
- Check swap.
- Check MySQL memory use.
- Identify competing services.
- Check buffer settings.
- Check connections.
- Avoid blind templates.
- Tune conservatively.
- Monitor after restart.
- Document assumptions.
Verification Steps
- Memory pressure is understood.
- MySQL settings fit server RAM.
- Swap does not grow unexpectedly.
- Application remains stable.
- Tuning decision is documented.
Rollback Plan
If tuning causes swap or crashes, restore the previous MySQL config and reduce memory-related settings before retesting.
Common Mistakes
- Copying large-server tuning values to a small VPS.
- Ignoring PHP-FPM memory.
- Setting max_connections too high.
- No monitoring after restart.
- Changing buffers without workload evidence.
Related Commands
free -h
swapon --show
ps aux --sort=-%mem | head
mysql -u root -p -e "SHOW VARIABLES LIKE 'innodb_buffer_pool_size';"
mysql -u root -p -e "SHOW VARIABLES LIKE 'max_connections';"
mysqladmin -u root -p status