Re: MySQL Performance Tuning Help

[Rick James]

Be sure to use GLOBAL, not the default of SESSION:

mysql> SHOW STATUS LIKE 'Opened_tables';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Opened_tables | 0     |
+---------------+-------+

mysql> SHOW GLOBAL STATUS LIKE 'Opened_tables';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Opened_tables | 460   |
+---------------+-------+

Then divide that by Uptime to get per-second.  Increase the table cache until that quotient is less than 1/sec.