MySQL是一種優秀的數據庫，它支持許多不同的指標來幫助用戶評估數據庫的性能和健康狀況。下面是一些常見的MySQL指標。

// 查看服務器版本SELECT VERSION();// 查看數據庫的總大小和使用的大小SELECT 
table_schema AS `Database`, 
SUM(data_length + index_length) / 1024 / 1024 AS `Size (MB)`, 
SUM(data_free) / 1024 / 1024 AS `Free (MB)` 
FROM 
information_schema.TABLES 
GROUP BY 
table_schema;// 查看當前連接數量SHOW STATUS like 'Threads_connected';// 查看緩存命中率SELECT 
ROUND((1 - (SUM(com_select) / (SUM(com_select) + SUM(com_insert) + SUM(com_update) + SUM(com_delete) + SUM(com_replace)))) * 100, 2) AS `Hit %` 
FROM 
information_schema.`GLOBAL_STATUS`;// 查看響應時間SELECT 
event_name AS `Name`, 
COUNT_STAR AS `Calls`, 
ROUND(SUM_TIMER_WAIT/1000000000000000, 6) AS `Time (s)`, 
ROUND(SUM_TIMER_WAIT/1000000000/COUNT_STAR, 6) AS `Avg (s)` 
FROM 
performance_schema.events_statements_summary_by_digest 
GROUP BY 
event_name 
ORDER BY 
`Time (s)` DESC;// 查看索引使用情況SELECT 
ROUND(SUM(rows_examined)/SUM(IFNULL(nullif(rows_sent, 0), 1))) AS `Scanned Rows Per Output Row` 
FROM 
performance_schema.events_statements_summary_by_digest 
WHERE 
digest_text LIKE '%FROM `table_name`%' 
AND digest_text NOT LIKE '%FROM `table_name` WHERE%';

這些MySQL指標可以幫助用戶監視數據庫的健康狀況、性能和流量。通過對這些指標的監控，用戶可以更好地了解他們的應用程序對數據庫的影響，從而優化應用程序和數據存儲。