等待状态是隔离SQL SERVER性能问题的一个重要手段，从实例级别入手。可以大概看出SQL SERVER在过去某段时间内是否处于某种资源的吃紧状态。不过取决于你是否有建立有效的性能数据收集机制。sys.dm_os_wait_stats这张DMV的数据是从实例上次启动起收集的。
WITH Waits AS
(
SELECT
wait_type,
wait_time_ms / 1000. AS wait_time_s,
100. * wait_time_ms / SUM(wait_time_ms) OVER() AS pct,
ROW_NUMBER() OVER(ORDER BY wait_time_ms DESC) AS rn
FROM sys.dm_os_wait_stats
WHERE wait_type
NOT IN
('CLR_SEMAPHORE', 'LAZYWRITER_SLEEP', 'RESOURCE_QUEUE',
'SLEEP_TASK', 'SLEEP_SYSTEMTASK', 'SQLTRACE_BUFFER_FLUSH', 'WAITFOR',
'CLR_AUTO_EVENT', 'CLR_MANUAL_EVENT')
) -- filter out additional irrelevant waits SELECT W1.wait_type,
CAST(W1.wait_time_s AS DECIMAL(12, 2)) AS wait_time_s,
CAST(W1.pct AS DECIMAL(12, 2)) AS pct,
CAST(SUM(W2.pct) AS DECIMAL(12, 2)) AS running_pct
FROM Waits AS W1
INNER JOIN Waits AS W2 ON W2.rn <= W1.rn
GROUP BY W1.rn,
W1.wait_type,
W1.wait_time_s,
W1.pct
HAVING SUM(W2.pct) - W1.pct < 95; -- percentage threshold;
可以通过下面命令reset数据收集
DBCC SQLPERF ('sys.dm_os_wait_stats', CLEAR);
GO
参考：