mySQL内部计数正在破坏我的查询性能

Question

SELECT DISTINCT cl.client，cl.clientUNIQUE，（SELECT COUNT（taskUNIQUE）AS countTasks FROM tasks WHERE state ='NF'AND clientUNIQUE = cl.clientUNIQUE AND status ='V'）AS ActiveTasks，（SELECT COUNT（projectUNIQUE） ）FROM项目WHERE status ='V'AND state！='end'AND clientUNIQUE = cl.clientUNIQUE）AS ActiveProjects FROM clients AS cl LEFT JOIN tasks AS tsk ON cl.clientUNIQUE = tsk.clientUNIQUE WHERE cl.status ='V' AND cl.accountUNIQUE ='[client] 0E2D3B21D716BB71A83331558656EC47'Order by ActiveTasks DESC LIMIT 10

This query takes about 5 second to run. Too many counts? Any suggestion to improve performance?

Answer 1

好的，这很尴尬，但我没有创建任何索引。感谢kmoser引导我找到答案的问题。