My Quick Upgrade Path
- Take backup of database(s)
- Take a backup of the my.cnf
- Stop the application
- Shutdown the database (cleanly)
- If rpm install then you can upgrade (rpm -U). I generally uninstall (rpm -e) and then install (rpm -i). If using a tarball, after uncompressing the tarball, you may need to change path parameters etc.
- Alter the my.cnf - please see later in the post.
- Startup the instance, you will receive many errors about structure in the mysqld.log
- Run mysql_upgrade, check the output for any tables that fail.
- I normally bounce the instance to ensure it is working
I normally set the following in the my.cnf:
# New in 5.6
max_allowed_packet = 4MB minimum
Remove - innodb_additional_mem_pool_size - deprecated
After a recent upgrade of a development database I had a follow-up call with the owner of the system to find that max_connections and max_open_files that had been set fairly high was suddenly much lower. After some searching I found the os limit set low, 1024 to be exact, but it's interesting and always something to check pre upgrades. At least it adds another step to my Quick Upgrade Path:
1. Check the o/s settings (ulimit -a)
Whilst researching this I have also found a very interesting post, which helped explain my problem. It's a very interesting read: