预测Recovery的剩余时间

当一个DB处于 In Recovery 状态时，用户是不能访问的，如果Recovery时间很长，那么对一个DBA来说，等待的过程是虐心的，DBA需要知道剩余的还原时间。如何预测一个DB从In Recovery 状态，还原到正常Online状态所需的时间？ 虽然SQL Server 没有直接给出答案，但是，可以通过Recovery的历史记录来预测。

DECLARE @DBName VARCHAR(64) = ‘databasename‘

DECLARE @ErrorLog AS TABLE([LogDate] CHAR(24), [ProcessInfo] VARCHAR(64), [TEXT] VARCHAR(MAX))

INSERT INTO @ErrorLog
EXEC master..sp_readerrorlog 0, 1, ‘Recovery of database‘, @DBName

SELECT TOP 11
     [LogDate]
    ,SUBSTRING([TEXT], CHARINDEX(‘) is ‘, [TEXT]) + 4,CHARINDEX(‘ complete (‘, [TEXT]) - CHARINDEX(‘) is ‘, [TEXT]) - 4) AS PercentComplete
    ,CAST(SUBSTRING([TEXT], CHARINDEX(‘approximately‘, [TEXT]) + 13,CHARINDEX(‘ seconds remain‘, [TEXT]) - CHARINDEX(‘approximately‘, [TEXT]) - 13) AS FLOAT)/60.0 AS MinutesRemaining
    ,CAST(SUBSTRING([TEXT], CHARINDEX(‘approximately‘, [TEXT]) + 13,CHARINDEX(‘ seconds remain‘, [TEXT]) - CHARINDEX(‘approximately‘, [TEXT]) - 13) AS FLOAT)/60.0/60.0 AS HoursRemaining
    ,[TEXT]

FROM @ErrorLog  ORDER BY [LogDate] DESC

引用于：

determining-how-long-a-database-will-be-in-recovery-sql-server-2008