Fix_VLFs.sql

-- 2011-05-24 Pedro Lopes (Microsoft) pedro.lopes@microsoft.com (http://aka.ms/sqlinsights)
--
-- 2012-03-25 Added SQL 2012 support
-- 2012-09-19 Simplified logic
-- 2012-09-20 Changed grow settings if not SQL Server 2012
--
-- Generates the sql statements to preemtively fix VLF issues in all DBs within the server, based on the transaction log current size.
--
SET NOCOUNT ON;

DECLARE @query VARCHAR(1000), @dbname VARCHAR(255), @count int, @usedlogsize bigint, @logsize bigint
DECLARE @sqlcmd NVARCHAR(1000), @sqlparam NVARCHAR(100), @filename VARCHAR(255), @i int, @recmodel NVARCHAR(128)
DECLARE @potsize int, @n_iter int, @n_iter_final int, @initgrow int, @n_init_iter int, @bckpath NVARCHAR(255)
DECLARE @majorver smallint, @minorver smallint, @build smallint

CREATE TABLE #loginfo (dbname varchar(100), num_of_rows int, used_logsize_MB DECIMAL(20,1))

DECLARE @tblvlf TABLE (dbname varchar(100), 
	Actual_log_size_MB DECIMAL(20,1), 
	Potential_log_size_MB DECIMAL(20,1), 
	Actual_VLFs int, 
	Potential_VLFs int, 
	Growth_iterations int,
	Log_Initial_size_MB DECIMAL(20,1), 
	File_autogrow_MB DECIMAL(20,1))
	
SELECT TOP 1 @bckpath = REVERSE(RIGHT(REVERSE(physical_device_name), LEN(physical_device_name)-CHARINDEX('\',REVERSE(physical_device_name),0))) FROM msdb.dbo.backupmediafamily WHERE device_type = 2

SELECT @majorver = (@@microsoftversion / 0x1000000) & 0xff, @minorver = (@@microsoftversion / 0x10000) & 0xff, @build = @@microsoftversion & 0xffff
 
--DECLARE csr CURSOR FAST_FORWARD FOR SELECT name FROM master..sysdatabases WHERE dbid > 4 AND DATABASEPROPERTYEX(name,'status') = 'ONLINE' AND DATABASEPROPERTYEX(name,'Updateability') = 'READ_WRITE' AND name <> 'tempdb' AND name <> 'ReportServerTempDB'
DECLARE csr CURSOR FAST_FORWARD FOR SELECT name FROM master.sys.databases WHERE is_read_only = 0 AND state = 0 AND database_id <> 2;
OPEN csr
FETCH NEXT FROM csr INTO @dbname
WHILE (@@FETCH_STATUS <> -1)
BEGIN
	CREATE TABLE #log_info (recoveryunitid int NULL,
	fileid tinyint,
	file_size bigint,
	start_offset bigint,
	FSeqNo int,
	[status] tinyint,
	parity tinyint,
	create_lsn numeric(25,0))

	SET @query = 'DBCC LOGINFO (' + '''' + @dbname + ''') WITH NO_INFOMSGS'
	IF @majorver < 11
	BEGIN
		INSERT INTO #log_info (fileid, file_size, start_offset, FSeqNo, [status], parity, create_lsn)
		EXEC (@query)
	END
	ELSE
	BEGIN
		INSERT INTO #log_info (recoveryunitid, fileid, file_size, start_offset, FSeqNo, [status], parity, create_lsn)
		EXEC (@query)
	END
	SET @count = @@ROWCOUNT
	SET @usedlogsize = (SELECT (MIN(l.start_offset) + SUM(CASE WHEN l.status <> 0 THEN l.file_size ELSE 0 END))/1024.00/1024.00 FROM #log_info l)
	DROP TABLE #log_info;
	INSERT #loginfo
	VALUES(@dbname, @count, @usedlogsize);
	FETCH NEXT FROM csr INTO @dbname
END

CLOSE csr
DEALLOCATE csr

PRINT '/* Generated on ' + CONVERT (VARCHAR, GETDATE()) + ' in ' + @@SERVERNAME + ' */' + CHAR(10)
	
DECLARE cshrk CURSOR FAST_FORWARD FOR SELECT dbname, num_of_rows FROM #loginfo 
WHERE num_of_rows >= 50 --My rule of thumb is 50 VLFs. Your mileage may vary.
ORDER BY dbname
OPEN cshrk
FETCH NEXT FROM cshrk INTO @dbname, @count
WHILE (@@FETCH_STATUS <> -1)
BEGIN
	SET @sqlcmd = 'SELECT @nameout = name, @logsizeout = (CAST(size AS BIGINT)*8)/1024 FROM [' + @dbname + '].dbo.sysfiles WHERE (64 & status) = 64'
	SET @sqlparam = '@nameout NVARCHAR(100) OUTPUT, @logsizeout bigint OUTPUT'
	EXEC sp_executesql @sqlcmd, @sqlparam, @nameout = @filename OUTPUT, @logsizeout = @logsize OUTPUT;
	PRINT '---------------------------------------------------------------------------------------------------------- '
	PRINT CHAR(13) + 'USE ' + QUOTENAME(@dbname) + ';'
	PRINT 'DBCC SHRINKFILE (N''' + @filename + ''', 1, TRUNCATEONLY);'
	PRINT '--'
	PRINT '-- CHECK: if the tlog file has shrunk with the following query:'
	PRINT 'SELECT name, (size*8)/1024 AS log_MB FROM [' + @dbname + '].dbo.sysfiles WHERE (64 & status) = 64'
	PRINT '--'
	SET @recmodel = CONVERT(NVARCHAR, DATABASEPROPERTYEX(@dbname,'Recovery'))
	IF @recmodel <> 'SIMPLE' 
	AND SERVERPROPERTY('EngineEdition') <> 8 -- This cannot be applied on Managed Instance
	BEGIN
		PRINT '-- If the log has not shrunk, you must backup the transaction log next.'
		PRINT '-- Repeat the backup and shrink process alternatively until you get the desired log size (about 1MB).'
		PRINT '--'
		PRINT '-- METHOD: Backup -> Shrink (repeat the backup and shrink process until the log has shrunk):'
		PRINT '--'
		PRINT '-- Create example logical backup device.' 
		PRINT 'USE master;' + CHAR(13) + 'EXEC sp_addumpdevice ''disk'', ''BckLog'', ''' + @bckpath + '\example_bck.trn'';'
		PRINT 'USE ' + QUOTENAME(@dbname) + ';'
		PRINT '-- Backup Log'
		PRINT 'BACKUP LOG ' + QUOTENAME(@dbname) + ' TO BckLog;'
		PRINT '-- Shrink'
		PRINT 'DBCC SHRINKFILE (N''' + @filename + ''', 1);'
		PRINT '--'
		PRINT '-- METHOD: Alter recovery model -> Shrink:'
		PRINT '-- NOTE: Because the database is in ' + @recmodel + ' recovery model, one alternative is to set it to SIMPLE to truncate the log, shrink it, and reset it to ' + @recmodel + '.'
		PRINT '-- NOTE2: This method of setting the recovery model to SIMPLE and back again WILL BREAK log chaining, and thus any log shipping or mirroring.'
		PRINT 'USE [master]; ' + CHAR(13) + 'ALTER DATABASE ' + QUOTENAME(@dbname) + ' SET RECOVERY SIMPLE;'
		PRINT 'USE ' + QUOTENAME(@dbname) + ';' + CHAR(13) + 'DBCC SHRINKFILE (N''' + @filename + ''', 1);'
		PRINT 'USE [master]; ' + CHAR(13) + 'ALTER DATABASE ' + QUOTENAME(@dbname) + ' SET RECOVERY ' + @recmodel + ';'
		PRINT '--'
		PRINT '-- CHECK: if the tlog file has shrunk with the following query:'
		PRINT 'SELECT name, (size*8)/1024 AS log_MB FROM [' + @dbname + '].dbo.sysfiles WHERE (64 & status) = 64'
	END
	ELSE
	BEGIN
		PRINT '-- If not, then proceed to the next step (it may be necessary to execute multiple times):'
		PRINT 'DBCC SHRINKFILE (N''' + @filename + ''', 1);'
		PRINT '-- CHECK: if the tlog file has shrunk with the following query:'
		PRINT 'SELECT name, (size*8)/1024 AS log_MB FROM [' + @dbname + '].dbo.sysfiles WHERE (64 & status) = 64'
	END

	-- We are growing in MB instead of GB because of known issue prior to SQL 2012.
	-- More detail here: http://www.sqlskills.com/BLOGS/PAUL/post/Bug-log-file-growth-broken-for-multiples-of-4GB.aspx
	-- and http://connect.microsoft.com/SQLServer/feedback/details/481594/log-growth-not-working-properly-with-specific-growth-sizes-vlfs-also-not-created-appropriately
	-- or https://connect.microsoft.com/SQLServer/feedback/details/357502/transaction-log-file-size-will-not-grow-exactly-4gb-when-filegrowth-4gb
	IF @majorver >= 11
	BEGIN
		SET @n_iter = (SELECT CASE WHEN @logsize <= 64 THEN 1
			WHEN @logsize > 64 AND @logsize < 256 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/256, 0)
			WHEN @logsize >= 256 AND @logsize < 1024 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/512, 0)
			WHEN @logsize >= 1024 AND @logsize < 4096 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/1024, 0)
			WHEN @logsize >= 4096 AND @logsize < 8192 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/2048, 0)
			WHEN @logsize >= 8192 AND @logsize < 16384 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/4096, 0)
			WHEN @logsize >= 16384 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/8192, 0)
			END)
		SET @potsize = (SELECT CASE WHEN @logsize <= 64 THEN 1*64
			WHEN @logsize > 64 AND @logsize < 256 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/256, 0)*256
			WHEN @logsize >= 256 AND @logsize < 1024 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/512, 0)*512
			WHEN @logsize >= 1024 AND @logsize < 4096 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/1024, 0)*1024
			WHEN @logsize >= 4096 AND @logsize < 8192 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/2048, 0)*2048
			WHEN @logsize >= 8192 AND @logsize < 16384 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/4096, 0)*4096
			WHEN @logsize >= 16384 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/8192, 0)*8192
			END)
	END
	ELSE
	BEGIN
		SET @n_iter = (SELECT CASE WHEN @logsize <= 64 THEN 1
			WHEN @logsize > 64 AND @logsize < 256 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/256, 0)
			WHEN @logsize >= 256 AND @logsize < 1024 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/512, 0)
			WHEN @logsize >= 1024 AND @logsize < 4096 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/1024, 0)
			WHEN @logsize >= 4096 AND @logsize < 8192 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/2048, 0)
			WHEN @logsize >= 8192 AND @logsize < 16384 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/4000, 0)
			WHEN @logsize >= 16384 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/8000, 0)
			END)
		SET @potsize = (SELECT CASE WHEN @logsize <= 64 THEN 1*64
			WHEN @logsize > 64 AND @logsize < 256 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/256, 0)*256
			WHEN @logsize >= 256 AND @logsize < 1024 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/512, 0)*512
			WHEN @logsize >= 1024 AND @logsize < 4096 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/1024, 0)*1024
			WHEN @logsize >= 4096 AND @logsize < 8192 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/2048, 0)*2048
			WHEN @logsize >= 8192 AND @logsize < 16384 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/4000, 0)*4000
			WHEN @logsize >= 16384 THEN ROUND(CONVERT(FLOAT, ROUND(@logsize, -2))/8000, 0)*8000
			END)
	END
	
	-- If the proposed log size is smaller than current log, and also smaller than 4GB,
	-- and there is less than 512MB of diff between the current size and proposed size, add 1 grow.
	SET @n_iter_final = @n_iter
	IF @logsize > @potsize AND @potsize <= 4096 AND ABS(@logsize - @potsize) < 512
	BEGIN
		SET @n_iter_final = @n_iter + 1
	END
	-- If the proposed log size is larger than current log, and also larger than 50GB, 
	-- and there is less than 1GB of diff between the current size and proposed size, take 1 grow.
	ELSE IF @logsize < @potsize AND @potsize <= 51200 AND ABS(@logsize - @potsize) > 1024
	BEGIN
		SET @n_iter_final = @n_iter - 1
	END

	IF @potsize = 0 
	BEGIN 
		SET @potsize = 64 
	END
	IF @n_iter = 0 
	BEGIN 
		SET @n_iter = 1
	END
	
	SET @potsize = (SELECT CASE WHEN @n_iter < @n_iter_final THEN @potsize + (@potsize/@n_iter) 
			WHEN @n_iter > @n_iter_final THEN @potsize - (@potsize/@n_iter) 
			ELSE @potsize END)
	
	SET @n_init_iter = @n_iter_final
	IF @potsize >= 8192
	BEGIN
		SET @initgrow = @potsize/@n_iter_final
	END
	IF @potsize >= 64 AND @potsize <= 512
	BEGIN
		SET @n_init_iter = 1
		SET @initgrow = 512
	END
	IF @potsize > 512 AND @potsize <= 1024
	BEGIN
		SET @n_init_iter = 1
		SET @initgrow = 1023
	END
	IF @potsize > 1024 AND @potsize < 8192
	BEGIN
		SET @n_init_iter = 1
		SET @initgrow = @potsize
	END

	INSERT INTO @tblvlf
	SELECT @dbname, @logsize, @potsize, @count, 
		CASE WHEN @potsize <= 64 THEN (@potsize/(@potsize/@n_init_iter))*4
			WHEN @potsize > 64 AND @potsize < 1024 THEN (@potsize/(@potsize/@n_init_iter))*8
			WHEN @potsize >= 1024 THEN (@potsize/(@potsize/@n_init_iter))*16
			END, 
		@n_init_iter, @initgrow, CASE WHEN (@potsize/@n_iter_final) <= 1024 THEN (@potsize/@n_iter_final) ELSE 1024 END
	
	SET @i = 0
	WHILE @i <= @n_init_iter
	BEGIN
		IF @i = 1
		BEGIN
			--Log Autogrow should not be above 1GB
			PRINT CHAR(13) + '-- Now for the log file growth:'
			PRINT 'ALTER DATABASE [' + @dbname + '] MODIFY FILE ( NAME = N''' + @filename + ''', SIZE = ' + CONVERT(VARCHAR, @initgrow) + 'MB , FILEGROWTH = ' + CASE WHEN (@potsize/@n_iter_final) <= 1024 THEN CONVERT(VARCHAR, (@potsize/@n_iter_final)) ELSE '1024' END + 'MB );'
		END
		IF @i > 1
		BEGIN
			PRINT 'ALTER DATABASE [' + @dbname + '] MODIFY FILE ( NAME = N''' + @filename + ''', SIZE = ' + CONVERT(VARCHAR, @initgrow*@i)+ 'MB );'
		END		
		SET @i = @i + 1
		CONTINUE
	END
	FETCH NEXT FROM cshrk INTO @dbname, @count
END
CLOSE cshrk
DEALLOCATE cshrk;

DROP TABLE #loginfo;

SELECT dbname AS [Database_Name], Actual_log_size_MB, Potential_log_size_MB, Actual_VLFs, 
	Potential_VLFs, Growth_iterations, Log_Initial_size_MB, File_autogrow_MB
FROM @tblvlf;
GO