table_open_cache – the number of cached open tables for all threads. Opening tables is a resource-intensive process, so it is recommended to keep a certain number of tables open in the cache.
Let’s see the current value (by default 400, minimum 1, maximum 524288):
mysql -u root -p show variables like "table_open_cache";
If you need to change the value without stopping the MySQL server, then:
set global table_open_cache=8192;
So that the value is not reset after restarting the MySQL server, open the configuration file in a text editor:
sudo nano /etc/mysql/mysql.conf.d/mysqld.cnf
And we specify:
The value of “open_files_limit” must be greater than the value of “table_open_cache”.
See also my article:
How to change open_files_limit in MySQL