I've configured my i7 64gb ssd server with centos7 with the following my.cnf

key_buffer = 12M
max_allowed_packet = 16M
table_cache = 4096
table_open_cache = 4096
table_definition_cache = 4096
sort_buffer_size = 48M
read_buffer_size = 32M
read_rnd_buffer_size = 104M
myisam_sort_buffer_size = 100M
myisam_max_sort_file_size = 1024m
#myisam_max_extra_sort_file_size = 1024m
myisam_repair_threads = 1
thread_cache_size = 32
query_cache_type = 1
query_cache_size = 512M
query_cache_limit = 8M
tmp_table_size = 256M
max_heap_table_size = 64M
#innodb_io_capacity = 400
#innodb_read_io_threads = 8
#innodb_write_io_threads = 8
#innodb_buffer_pool_instances = 8
innodb_buffer_pool_size = 3G
innodb_additional_mem_pool_size = 24M

But when i run mysql_tuner.pl i still get

Current table_open_cache = 482 tables
Current table_definition_cache = 4096 tables
You have a total of 1027 tables
You have 482 open tables.
Current table_cache hit rate is 15%
, while 100% of your table cache is in use
You should probably increase your table_cache

Of course i restarted my mariadb instance. but i have no clue. Search turned up empty as well.

Hope someone could help out Cheers.

  • Do you see Opened_table incrementing as time passes? You could check with mysqladmin -r -i 5 extended-status | grep Opened. What is max number of file descriptors that mysqld user can opend? You could check with ulimit -a | grep files.
    – Giovanni
    Mar 25, 2015 at 10:57

1 Answer 1


The operating system has a low limit. In Unix, see ulimit -n, and change it. Some versions have an unnecessarily low limit of 1024.

Most, but not all, things set by my.cnf (my.ini) stay set. table_open_cache is one that is changed based on the environment. Use SHOW VARIABLES to see the real values. Or SHOW VARIABLES LIKE 'table_open_cache' to see the one setting.

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