Open Table Cache Thrashing
infoTable cache insufficient for working set, causing frequent table opens/closes. High table cache miss rate degrades performance as MySQL repeatedly opens/closes table files, consuming CPU and causing latency spikes.
mysql.performance.table_cache_misses / (mysql.performance.table_cache_hits + mysql.performance.table_cache_misses) > 0.2, with mysql.performance.opened_tables rate > 10/sec and mysql.performance.open_tables approaching table_open_cache limit
Check table_open_cache setting against number of tables and concurrent connections. Calculate required cache size: (max_connections * average_tables_per_query) + margin. Increase table_open_cache if mysql.performance.open_tables consistently approaches limit. Monitor mysql.performance.opened_tables cumulative counter - if growing rapidly, cache is too small. Each cache entry uses file descriptors, so ensure open_files_limit is adequate. Check mysql.performance.open_files against open_files_limit.