SQL Server - Database Administration

SQL Server jobs on production instances

Tara Kizer — Mon, 30 Jun 2008 16:46:36 GMT

The most important thing that a Database Administrator does is backups. To automate them, we schedule them as jobs. But what other jobs are important on SQL Server instances?

Here are the jobs that I have on every SQL Server 2005 production instance:

Name	Code	Schedule	Notes
Backup System Databases	EXEC isp_Backup @path = 'F:\Backup\', @dbType = 'System', @bkpType = 'Full', @retention = 5, @liteSpeed = 'N'	Daily
Backup Transaction Logs	EXEC isp_Backup @path = 'F:\Backup\', @dbType = 'User', @bkpType = 'TLog', @retention = 5, @liteSpeed = 'Y'	Every 15 minutes
Backup User Databases	EXEC isp_Backup @path = 'F:\Backup\', @dbType = 'User', @bkpType = 'Full', @retention = 5, @liteSpeed = 'Y'	Daily
Defragment Indexes	EXEC isp_ALTER_INDEX @dbName = @dbName, @statsMode = 'SAMPLED', @defragType = 'REBUILD', @minFragPercent = 10, @maxFragPercent = 100, @minRowCount = 1000	Daily or weekly	Loop through each database, see this for sample code.
Delete Backup History	DECLARE @d datetime SET @d = DATEADD(day, -30, GETDATE()) EXEC msdb.dbo.sp_delete_backuphistory @d	Daily or weekly	See this for more details.
Delete Database Mail History	DECLARE @d datetime SET @d = DATEADD(dd, -5, GETDATE()) EXEC msdb.dbo.sysmail_delete_mailitems_sp @sent_before = @d	Daily or weekly	Needed only on systems that send mail with attachments using Database Mail. See this for more details.
Integrity Checks	EXEC isp_DBCC_CHECKDB	Daily
Update Statistics	EXEC isp_UPDATE_STATISTICS @dbName = @dbName, @sample = 25	Daily	Might not be needed if your indexes are getting defragmented daily. Loop through each database, see this for sample code.

Do you have any jobs that you put on every production SQL Server instance that I didn't cover? If you do, I'd love to hear from you.

Idera's SQL admin toolset

Tara Kizer — Wed, 11 Jun 2008 20:43:16 GMT

We are required to start auditing our SQL Servers for various data points. We did not want to write a custom tool if at all possible, so we started looking for third-party products. We found Idera's SQL admin toolset. It doesn't collect all of the information that we want to audit, but it's a great start.

Excerpt from their site about the tool:

Are you a DBA or developer tired of spending countless hours on routine administrative and troubleshooting tasks, like figuring out why a user can't connect, or moving databases, or producing reports for your boss to show that the backups really did run, or finding rogue SQL Servers, or checking configurations or…. yeah, we know, the list is endless.

If the answer is yes then, you need our SQL admin toolset. Packed with 24 powerful tools that will make troubleshooting, administration and reporting such a breeze you'll be wondering what to do with all the spare time you have on your hands - really! Download now and see.

I do not work for Idera. I am not getting paid to write this nor was I asked to write this. I found this tool to be so useful that I wanted to bring it to other's attention, especially since it's free to use right now.

How to troubleshoot SQL Server connectivity problems

Tara Kizer — Fri, 23 May 2008 17:53:54 GMT

We often get asked in the SQLTeam forums why they can't connect to a SQL Server instance. They provide the typical connectivity error.

In SQL Server 2000, the error is:

SQL Server does not exist or access denied.

In SQL Server 2005, the error is:

An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections.

Both errors are misleading as they are not usually resolved by providing access or enabling remote connections. In fact, I've never seen the SQL Server 2000 error to be as a result of lack of access. If someone doesn't have access, they will get the "Login failed" error.

Here is an example thread where I helped the original poster and someone who hijacked the thread get connected to their respective SQL Server instances. Here is another example.

Recently, I found this MSDN blog post. It has a bunch of typographical errors, but it is very detailed and should help resolve most connection problems. The most important typo is netstat is spelled as netstate. If the user doesn't realize that the command is netstat, they will get an error which could lead them in the wrong direction when troubleshooting this issue. Hopefully the blog post will get corrected at some point.

Rather than linking to the SQLTeam threads I mentioned above when I see new threads with these errors, I will now be pointing them to this blog post. Between the 3 links, the person should be able to resolve their problem.

Backup databases stored procedure - new version

Tara Kizer — Wed, 21 May 2008 17:05:43 GMT

I have updated my backup stored procedure, isp_Backup, as the old version had two issues. It did not exclude database snapshots, which can't be backed up. It also was not checking for the number of CPUs in the registry properly. The CPU check only affects backups when SQL Litespeed is used.

In the next version, I will exclude those databases that are being log shipped by SQL Litespeed as we don't want to interfere with the LSNs. I am already checking for this condition for native backups. I will also add code to perform a full backup when it is performing a differential or transaction log backup and a full backup does not exist. This will be done to avoid backup errors.

----------------------------------------------------------------------------------------------------
-- OBJECT NAME            : isp_Backup
--
-- AUTHOR               : Tara Kizer
--
-- INPUTS                : @path - location of the backups, default backup directory used if @path is null
--                          @dbType - which database(s) to backup
--                            All, System, User, or dash followed by database name (ex. -Toolbox)
--                          @bkpType - type of backup to perform
--                            Full, TLog, Diff
--                          @retention - number of days to retain backups, -1 to retain all files
--                          @liteSpeed - perform backup using LiteSpeed (Imceda product)
--                            N, Y
--
-- OUTPUTS                : None
--
-- RETURN CODES            : 0-10 (see @error table variable at the end for the messages)
--
-- DEPENDENCIES            : None
--
-- DESCRIPTION            : Performs backups.
--
-- EXAMPLES (optional)  : EXEC isp_Backup @path = 'C:\MSSQL\Backup\', @dbType = 'All', @bkpType = 'Full', @retention = 5, @liteSpeed = 'N'
----------------------------------------------------------------------------------------------------
CREATE PROC [dbo].[isp_Backup]
(@path varchar(100), @dbType sysname = 'All', @bkpType char(4) = 'Full', @retention smallint = 2, @liteSpeed char(1) = 'N')
AS

SET NOCOUNT ON

DECLARE @now char(14)             -- current date in the form of yyyymmddhhmmss
DECLARE @dbName sysname         -- database name that is currently being processed
DECLARE @cmd nvarchar(4000)     -- dynamically created DOS command
DECLARE @result int             -- result of the dir DOS command
DECLARE @rowCnt int             -- @@ROWCOUNT
DECLARE @fileName varchar(200)    -- path and file name of the BAK file
DECLARE @edition int            -- edition of SQL Server (1 - Personal or Desktop Engine; 2 - Standard; 3 - Developer or Enterprise)
DECLARE @rc int                    -- return code
DECLARE @extension char(4)        -- extension for backup file
DECLARE @version char(1)        -- one digit version number, i.e. 8 (2000) or 9 (2005)

-- log shipping tables have been renamed in 2005
SET @version = CONVERT(char(1), SERVERPROPERTY('ProductVersion'))

IF @version NOT IN ('8', '9')
BEGIN
    SET @rc = 1
    GOTO EXIT_ROUTINE
END

-- Enterprise and Developer editions have msdb.dbo.log_shipping* tables, other editions do not
SET @edition = CONVERT(int, SERVERPROPERTY('EngineEdition'))

-- validate input parameters
IF @dbType IS NOT NULL AND @dbType NOT IN ('All', 'System', 'User') AND @dbType NOT LIKE '-%'
BEGIN
    SET @rc = 2
    GOTO EXIT_ROUTINE
END

IF @dbType LIKE '-%' AND @version = '8'
BEGIN
    IF NOT EXISTS (SELECT * FROM master.dbo.sysdatabases WHERE [name] = SUBSTRING(@dbType, 2, DATALENGTH(@dbType)))
    BEGIN
        SET @rc = 3
        GOTO EXIT_ROUTINE
    END
END
ELSE IF @dbType LIKE '-%' AND @version = '9'
BEGIN
    IF NOT EXISTS (SELECT * FROM master.sys.databases WHERE [name] = SUBSTRING(@dbType, 2, DATALENGTH(@dbType)))
    BEGIN
        SET @rc = 3
        GOTO EXIT_ROUTINE
    END
END

IF @bkpType IS NOT NULL AND @bkpType NOT IN ('Full', 'TLog', 'Diff')
BEGIN
    SET @rc = 4
    GOTO EXIT_ROUTINE
END

IF @dbType = 'System' AND @bkpType <> 'Full'
BEGIN
    SET @rc = 5
    GOTO EXIT_ROUTINE
END

IF @liteSpeed IS NOT NULL AND @liteSpeed NOT IN ('N', 'Y')
BEGIN
    SET @rc = 6
    GOTO EXIT_ROUTINE
END

-- use the default backup directory if @path is null
IF @path IS NULL
    EXEC master.dbo.xp_instance_regread N'HKEY_LOCAL_MACHINE',N'Software\Microsoft\MSSQLServer\MSSQLServer',N'BackupDirectory', @path output, 'no_output'

-- we need the backslash after the path, so add it if it wasn't provided in the input parameter
IF RIGHT(@path, 1) <> '\'
    SET @path = @path + '\'

CREATE TABLE #WhichDatabase(dbName SYSNAME NOT NULL)

-- put the databases to be backed up into temp table
IF @dbType LIKE '-%'
BEGIN
    IF @bkpType = 'TLog' AND DATABASEPROPERTYEX(SUBSTRING(@dbType, 2, DATALENGTH(@dbType)), 'RECOVERY') = 'SIMPLE'
    BEGIN
        SET @rc = 7
        GOTO EXIT_ROUTINE
    END
    
    IF @edition = 3
    BEGIN
        IF @version = '8'
        BEGIN
            IF EXISTS (SELECT * FROM msdb.dbo.log_shipping_databases WHERE database_name = SUBSTRING(@dbType, 2, DATALENGTH(@dbType)))
            BEGIN
                SET @rc = 8
                GOTO EXIT_ROUTINE
            END
        END
        ELSE IF @version = '9' 
        BEGIN
            IF EXISTS (SELECT * FROM msdb.dbo.log_shipping_primary_databases WHERE primary_database = SUBSTRING(@dbType, 2, DATALENGTH(@dbType)))
            BEGIN
                SET @rc = 8
                GOTO EXIT_ROUTINE
            END
        END
    END

    IF @version = '9'
    BEGIN
        IF EXISTS (SELECT * FROM master.sys.databases WHERE [name] = SUBSTRING(@dbType, 2, DATALENGTH(@dbType)) AND source_database_id IS NOT NULL)
        BEGIN
            SET @rc = 11
            GOTO EXIT_ROUTINE
        END
    END

    INSERT INTO #WhichDatabase(dbName)
    VALUES(SUBSTRING(@dbType, 2, DATALENGTH(@dbType))) 
END
ELSE IF @dbType = 'All' 
BEGIN
    IF @edition = 3 AND @version = '8'
        INSERT INTO #WhichDatabase (dbName)
        SELECT [name]
        FROM master.dbo.sysdatabases
        WHERE 
            [name] NOT IN ('tempdb', 'ReportServerTempDB') AND
            [name] NOT IN (SELECT database_name FROM msdb.dbo.log_shipping_databases) AND
            DATABASEPROPERTYEX([name], 'IsInStandBy') = 0 AND
            DATABASEPROPERTYEX([name], 'Status') = 'ONLINE'
        ORDER BY [name]
    ELSE IF @edition = 3 AND @version = '9'
        INSERT INTO #WhichDatabase (dbName)
        SELECT [name]
        FROM master.sys.databases
        WHERE 
            [name] NOT IN ('tempdb', 'ReportServerTempDB') AND
            [name] NOT IN (SELECT primary_database FROM msdb.dbo.log_shipping_primary_databases) AND
            DATABASEPROPERTYEX([name], 'IsInStandBy') = 0 AND
            DATABASEPROPERTYEX([name], 'Status') = 'ONLINE'
        ORDER BY [name]
    ELSE IF @version = '8'
        INSERT INTO #WhichDatabase (dbName)
        SELECT [name]
        FROM master.dbo.sysdatabases
        WHERE 
            [name] NOT IN ('tempdb', 'ReportServerTempDB') AND
            DATABASEPROPERTYEX([name], 'IsInStandBy') = 0 AND
            DATABASEPROPERTYEX([name], 'Status') = 'ONLINE'
        ORDER BY [name]
    ELSE -- version is 9
        INSERT INTO #WhichDatabase (dbName)
        SELECT [name]
        FROM master.sys.databases
        WHERE 
            [name] NOT IN ('tempdb', 'ReportServerTempDB') AND
            DATABASEPROPERTYEX([name], 'IsInStandBy') = 0 AND
            DATABASEPROPERTYEX([name], 'Status') = 'ONLINE'
        ORDER BY [name]
END
ELSE IF @dbType = 'System'
BEGIN
    IF @version = 8
        INSERT INTO #WhichDatabase (dbName)
        SELECT [name]
        FROM master.dbo.sysdatabases
        WHERE [name] IN ('master', 'model', 'msdb')
        ORDER BY [name]
    ELSE
        INSERT INTO #WhichDatabase (dbName)
        SELECT [name]
        FROM master.sys.databases
        WHERE [name] IN ('master', 'model', 'msdb')
        ORDER BY [name]
END
ELSE IF @dbType = 'User'
BEGIN
    IF @edition = 3 AND @version = '8'
        INSERT INTO #WhichDatabase (dbName)
        SELECT [name]
        FROM master.dbo.sysdatabases
        WHERE 
            [name] NOT IN ('master', 'model', 'msdb', 'tempdb', 'ReportServerTempDB') AND
            [name] NOT IN (SELECT database_name FROM msdb.dbo.log_shipping_databases) AND
            DATABASEPROPERTYEX([name], 'IsInStandBy') = 0 AND
            DATABASEPROPERTYEX([name], 'Status') = 'ONLINE'
        ORDER BY [name]
    ELSE IF @edition = 3 AND @version = '9'
        INSERT INTO #WhichDatabase (dbName)
        SELECT [name]
        FROM master.sys.databases
        WHERE 
            [name] NOT IN ('master', 'model', 'msdb', 'tempdb', 'ReportServerTempDB') AND
            [name] NOT IN (SELECT primary_database FROM msdb.dbo.log_shipping_primary_databases) AND
            DATABASEPROPERTYEX([name], 'IsInStandBy') = 0 AND
            DATABASEPROPERTYEX([name], 'Status') = 'ONLINE'
        ORDER BY [name]
    ELSE IF @version = '8'
        INSERT INTO #WhichDatabase (dbName)
        SELECT [name]
        FROM master.dbo.sysdatabases
        WHERE 
            [name] NOT IN ('master', 'model', 'msdb', 'tempdb', 'ReportServerTempDB') AND
            DATABASEPROPERTYEX([name], 'IsInStandBy') = 0 AND
            DATABASEPROPERTYEX([name], 'Status') = 'ONLINE'
        ORDER BY [name]
    ELSE
        INSERT INTO #WhichDatabase (dbName)
        SELECT [name]
        FROM master.sys.databases
        WHERE 
            [name] NOT IN ('master', 'model', 'msdb', 'tempdb', 'ReportServerTempDB') AND
            DATABASEPROPERTYEX([name], 'IsInStandBy') = 0 AND
            DATABASEPROPERTYEX([name], 'Status') = 'ONLINE'
        ORDER BY [name]
END
ELSE -- no databases to be backed up
BEGIN
    SET @rc = 9
    GOTO EXIT_ROUTINE
END

-- Remove snapshots
IF @version = '9'
    DELETE t
    FROM #WhichDatabase t 
    INNER JOIN master.sys.databases d
    ON t.dbName = d.[name]
    WHERE d.source_database_id IS NOT NULL

-- Get the database to be backed up
SELECT TOP 1 @dbName = dbName
FROM #WhichDatabase

SET @rowCnt = @@ROWCOUNT

-- Iterate throught the temp table until no more databases need to be backed up
WHILE @rowCnt <> 0
BEGIN 

    IF @bkpType = 'TLog' AND @dbType IN ('All', 'User') AND DATABASEPROPERTYEX(@dbName, 'RECOVERY') = 'SIMPLE'
        PRINT 'Skipping transaction log backup of ' + @dbName
    ELSE IF @bkpType = 'Diff' AND @dbName IN ('master', 'model', 'msdb')
        PRINT 'Skipping differential backup of ' + @dbName
    ELSE
    BEGIN
        -- Build the dir command that will check to see if the directory exists
        SET @cmd = 'dir ' + @path + @dbName
    
        -- Run the dir command, put output of xp_cmdshell into @result
        EXEC @result = master..xp_cmdshell @cmd, NO_OUTPUT
    
        -- If the directory does not exist, we must create it
        IF @result <> 0
        BEGIN
            -- Build the mkdir command        
            SET @cmd = 'mkdir ' + @path + @dbName
    
            -- Create the directory
            EXEC master..xp_cmdshell @cmd, NO_OUTPUT
    
            IF @@ERROR <> 0
            BEGIN
                SET @rc = 10
                GOTO EXIT_ROUTINE
            END
        END
        -- The directory exists, so let's delete files older than two days
        ELSE IF @retention <> -1
        BEGIN
            -- Stores the name of the file to be deleted
            DECLARE @whichFile VARCHAR(1000)
    
            CREATE TABLE #DeleteOldFiles(DirInfo VARCHAR(7000))
    
            -- Build the command that will list out all of the files in a directory
            SELECT @cmd = 'dir ' + @path + @dbName + ' /OD'
    
            -- Run the dir command and put the results into a temp table
            INSERT INTO #DeleteOldFiles
            EXEC master..xp_cmdshell @cmd
    
            -- Delete all rows from the temp table except the ones that correspond to the files to be deleted
            DELETE FROM #DeleteOldFiles
            WHERE ISDATE(SUBSTRING(DirInfo, 1, 10)) = 0 OR DirInfo LIKE '%<DIR>%' OR SUBSTRING(DirInfo, 1, 10) >= GETDATE() - @retention
    
            -- Get the file name portion of the row that corresponds to the file to be deleted
            SELECT TOP 1 @whichFile = SUBSTRING(DirInfo, LEN(DirInfo) -  PATINDEX('% %', REVERSE(DirInfo)) + 2, LEN(DirInfo)) 
            FROM #DeleteOldFiles        
    
            SET @rowCnt = @@ROWCOUNT
            
            -- Interate through the temp table until there are no more files to delete
            WHILE @rowCnt <> 0
            BEGIN
                -- Build the del command
                SELECT @cmd = 'del ' + @path + + @dbName + '\' + @whichFile + ' /Q /F'
                
                -- Delete the file
                EXEC master..xp_cmdshell @cmd, NO_OUTPUT
                
                -- To move to the next file, the current file name needs to be deleted from the temp table
                DELETE FROM #DeleteOldFiles
                WHERE SUBSTRING(DirInfo, LEN(DirInfo) -  PATINDEX('% %', REVERSE(DirInfo)) + 2, LEN(DirInfo))  = @whichFile
    
                -- Get the file name portion of the row that corresponds to the file to be deleted
                SELECT TOP 1 @whichFile = SUBSTRING(DirInfo, LEN(DirInfo) -  PATINDEX('% %', REVERSE(DirInfo)) + 2, LEN(DirInfo)) 
                FROM #DeleteOldFiles
            
                SET @rowCnt = @@ROWCOUNT
            END
            DROP TABLE #DeleteOldFiles
        END
        -- Get the current date using style 120, remove all dashes, spaces, and colons
        SET @now = REPLACE(REPLACE(REPLACE(CONVERT(VARCHAR(50), GETDATE(), 120), '-', ''), ' ', ''), ':', '')
    
        SET @extension =
            CASE
                WHEN @bkpType = 'Full' THEN '.BAK'
                WHEN @bkpType = 'TLog' THEN '.TRN'
                ELSE '.DIF'
            END
    
        -- Build the backup path and file name, backup the database
        IF @liteSpeed = 'N'
        BEGIN
            SET @fileName = @path + @dbName + '\' + @dbName + '_' + @now + @extension
            IF @bkpType = 'FULL'
                BACKUP DATABASE @dbName
                TO DISK = @filename
                WITH INIT
            ELSE IF @bkpType = 'DIFF'
                BACKUP DATABASE @dbName
                TO DISK = @filename
                WITH INIT, DIFFERENTIAL
            ELSE
                BACKUP LOG @dbName
                TO DISK = @filename
                WITH INIT    
        END
        ELSE
        BEGIN
            SET @fileName = @path + @dbName + '\' + @dbName + '_LS_' + @now + @extension
    
            DECLARE @regOutput varchar(20) -- stores the output from the registry
            DECLARE @numProcs INT -- stores the number of processors that the server has registered

            -- Get the number of processors that the server has
            EXEC master..xp_regread 
                  @rootkey = 'HKEY_LOCAL_MACHINE', 
                  @key = 'SYSTEM\CurrentControlSet\Control\Session Manager\Environment\',
                  @value_name = 'NUMBER_OF_PROCESSORS',
                  @value = @regOutput OUTPUT
            
            --  We want n - 1 threads, where n is the number of processors
            SET @numProcs = CONVERT(int, @regOutput) - 1
    
            IF @bkpType = 'FULL'
                EXEC master.dbo.xp_backup_database
                    @database = @dbName,
                    @filename = @fileName,
                    @threads = @numProcs,
                    @init = 1
            ELSE IF @bkpType = 'DIFF'
                EXEC master.dbo.xp_backup_database
                    @database = @dbName,
                    @filename = @fileName,
                    @threads = @numProcs,
                    @init = 1,
                    @with = 'DIFFERENTIAL'
            ELSE
                EXEC master.dbo.xp_backup_log
                    @database = @dbName,
                    @filename = @fileName,
                    @threads = @numProcs,
                    @init = 1
        END
    END
        -- To move onto the next database, the current database name needs to be deleted from the temp table
        DELETE FROM #WhichDatabase
        WHERE dbName = @dbName
    
        -- Get the database to be backed up
        SELECT TOP 1 @dbName = dbName
        FROM #WhichDatabase
    
        SET @rowCnt = @@ROWCOUNT
        
        -- Let the system rest for 5 seconds before starting on the next backup
        WAITFOR DELAY '00:00:05'
END

SET @rc = 0

EXIT_ROUTINE:

IF @rc <> 0
BEGIN
    DECLARE @rm varchar(500)
    DECLARE @error table (returnCode int PRIMARY KEY CLUSTERED, returnMessage varchar(500))

    INSERT INTO @error(returnCode, returnMessage)
    SELECT  0, 'Success' UNION ALL
    SELECT  1, 'Version is not 2000 or 2005' UNION ALL
    SELECT  2, 'Invalid option passed to @dbType' UNION ALL
    SELECT  3, 'Database passed to @dbType does not exist' UNION ALL
    SELECT  4, 'Invalid option passed to @bkpType' UNION ALL
    SELECT  5, 'Only full backups are allowed on system databases' UNION ALL
    SELECT  6, 'Invalid option passed to @liteSpeed' UNION ALL
    SELECT  7, 'Can not backup tlog when using SIMPLE recovery model' UNION ALL
    SELECT  8, 'Will not backup the tlog on a log shipped database' UNION ALL
    SELECT  9, 'No databases to be backed up' UNION ALL
    SELECT 10, 'Unable to create directory' UNION ALL
    SELECT 11, 'Can not backup database snapshots'

    SELECT @rm = returnMessage 
    FROM @error 
    WHERE returnCode = @rc

    RAISERROR(@rm, 16, 1)
END

RETURN @rc

Optimizing tempdb

Tara Kizer — Tue, 20 May 2008 18:17:25 GMT

To improve query performance when you've found tempdb to be a performance bottleneck, you can create multiple data files of equal size. It is recommended that you add one file per CPU (per core, not per socket). The below script will do this for you. It is written as a stored procedure as I like to keep all of my scripts in an admin-type database. You will probably only run this once per instance though.

To determine how big each file should be, look at the size of your tempdb's data file which by default is named tempdb.mdf. You should check the file size after your system has been running for a while after a reboot or a restart of the SQL Server service. For instance, we typically reboot our database servers once a month due to the monthly Microsoft security patches. In my environment, I would check the file size about 30 days after the reboot so that I know it is at its typical maximum value.

As an example, if the file size is 8 GB and you've got 8 CPUs, then I would suggest passing a minimum of 1024 to the stored procedure as the inputs accept megabytes.

You should run the stored procedure after a reboot or a restart of the SQL Server service so that tempdb is at its smallest, which should avoid any errors.

If you've already set the initial size of tempdb to be greater than the value passed to the stored procedure, it will error as you can not reduce the setting with ALTER DATABASE. You must first set the initial size to a lower value. I have only seen one way to do this, which can be found in this thread. Check out rklime's post on 10-23-2007 at 10:05 AM.

This tempdb architecture is described in SQL Server Books Online. Here is the online reference for the article.

Although this TechNet article is long, it is a must read for database administrators as it goes into great detail about tempdb.

Here is the stored procedure:

----------------------------------------------------------------------------------------------------
-- OBJECT NAME        : isp_AddTempdbFiles
--
-- AUTHOR            : Tara Kizer
--
-- DATE                : May 13, 2008
--
-- INPUTS            : @size - size of the tempdb files in megabytes
--                      @growth - growth increment of the tempdb files in megabytes
--
-- OUTPUTS            : None
--
-- RETURN CODES        : None
--
-- DESCRIPTION        : Adds one tempdb file per CPU
--
-- EXAMPLE            : EXEC isp_AddTempdbFiles @size = 1024, @growth = 200
----------------------------------------------------------------------------------------------------
ALTER PROC [dbo].[isp_AddTempdbFiles]
(@size int, @growth int)
AS

SET NOCOUNT ON

DECLARE 
    @regOutput varchar(20), @numProcs int, @sql nvarchar(4000), @tempdbDataFileCount tinyint, @tempdbDataFileSize int,
    @tempdbFirstLogicalName sysname, @tempdbDataFileId tinyint, @i tinyint, @j tinyint,
    @tempdbMissingDataFileCount tinyint, @tempdbLogicalName sysname, @tempdbFirstPhysicalPath nvarchar(260)

EXEC master..xp_regread 
      @rootkey = 'HKEY_LOCAL_MACHINE', 
      @key = 'SYSTEM\CurrentControlSet\Control\Session Manager\Environment\',
      @value_name = 'NUMBER_OF_PROCESSORS',
      @value = @regOutput OUTPUT

SET @numProcs = @regOutput

SELECT @i = 2, @j = 2, @tempdbDataFileCount = COUNT(*), @tempdbDataFileId = MIN(file_id) 
FROM tempdb.sys.database_files 
WHERE type = 0

SET @tempdbMissingDataFileCount = @numProcs - @tempdbDataFileCount

IF @tempdbDataFileCount <> @numProcs
BEGIN
    SELECT 
        @tempdbFirstLogicalName = name, 
        @tempdbFirstPhysicalPath = 
            SUBSTRING(physical_name, 1, LEN(physical_name) - CHARINDEX('\', REVERSE(physical_name )) + 1)
    FROM tempdb.sys.database_files 
    WHERE file_id = @tempdbDataFileId

    SET @tempdbDataFileId = 0

    -- file exists, expand it, if necessary. to make sure they will all be the same
    WHILE @tempdbDataFileCount <> 0
    BEGIN
        SELECT @tempdbDataFileId = MIN(file_id)
        FROM tempdb.sys.database_files
        WHERE type = 0 AND file_id > @tempdbDataFileId

        SELECT @tempdbLogicalName = name, @tempdbDataFileSize = size
        FROM tempdb.sys.database_files 
        WHERE file_id = @tempdbDataFileId

        IF @size*1024/8 > @tempdbDataFileSize
        BEGIN
            SET @sql = 'ALTER DATABASE tempdb MODIFY FILE (NAME = N''' + @tempdbLogicalName + ''', SIZE = ' 
            SET @sql = @sql + CONVERT(varchar(10), @size) + 'MB, FILEGROWTH = ' + CONVERT(varchar(10), @growth) + 'MB)'
            --PRINT @sql
            EXEC (@sql)
        END

        SET @tempdbDataFileCount = @tempdbDataFileCount - 1
    END

    -- missing files
    WHILE @tempdbMissingDataFileCount <> 0
    BEGIN
        WHILE 1 = 1
        BEGIN
            IF EXISTS 
            (
                SELECT * 
                FROM tempdb.sys.database_files 
                WHERE name = @tempdbFirstLogicalName + CONVERT(varchar(3), @i)
            )
                SET @i = @i + 1
            ELSE
                BREAK
        END

        WHILE 1 = 1
        BEGIN
            IF EXISTS 
            (
                SELECT * 
                FROM tempdb.sys.database_files 
                WHERE physical_name = @tempdbFirstPhysicalPath + @tempdbFirstLogicalName + CONVERT(varchar(3), @j) + '.ndf'
            )
                SET @j = @j + 1
            ELSE
                BREAK
        END

        SET @sql = 'ALTER DATABASE tempdb ADD FILE (NAME = N''' + @tempdbFirstLogicalName + CONVERT(varchar(3), @i)
        SET @sql = @sql + ''', FILENAME = N''' + @tempdbFirstPhysicalPath + @tempdbFirstLogicalName + CONVERT(varchar(3), @j)
        SET @sql = @sql + '.ndf' + ''', SIZE = ' + CONVERT(varchar(10), @size) + 'MB, FILEGROWTH = '
        SET @sql = @sql + CONVERT(varchar(10), @growth) + 'MB)'
        --PRINT @sql
        EXEC (@sql)

        SET @tempdbMissingDataFileCount = @tempdbMissingDataFileCount - 1
    END
END

How to properly check for data corruption via a SQL job

Tara Kizer — Tue, 06 May 2008 23:13:58 GMT

I recently found out that we are not properly checking for data corruption in our "Integrity Checks" SQL job. I thought that a SQL job would fail if the job step that runs DBCC CHECKDB returned errors, but apparently that's not the case. Check out Paul Randal's blog for more information.

To properly check for data corruption via a SQL job, you should raise an error if @@ERROR does not equal zero.

In the next few days, I'll rewrite my isp_DBCC_CHECKDB stored procedure to include this. I will be testing my code change against a database that contains corruption. See this thread for more information.

UPDATE: We were unable to find a case where the job would show success, yet data corruption exists. Check out Paul's blog and the thread that I mentioned for more details.

How to failover Database Mirroring in SQL Server 2005 using T-SQL

Tara Kizer — Sun, 04 May 2008 21:50:14 GMT

I've previously shown how to setup Database Mirroring in SQL Server 2005 with T-SQL, but how do you failover to the mirrored databases using T-SQL? Here's how:

--Run on principal
USE master
GO

ALTER DATABASE dbName SET SAFETY FULL
GO
ALTER DATABASE dbName SET PARTNER FAILOVER
GO

--Run on new principal
USE master
GO

ALTER DATABASE dbName SET SAFETY OFF
GO

If you are using synchronous database mirroring, just ignore the "SET SAFETY" commands.

We use asynchronous database mirroring for performance reasons as our sites are 300 miles apart. Even though we have a fast network in between the two sites, the latency is too high when we tried it in synchronous mode.

Error when installing instance on a cluster

Tara Kizer — Tue, 29 Apr 2008 23:52:48 GMT

If you need to install a SQL Server 2005 instance on a cluster, make sure that there aren't any remote connections to any of the other nodes. Otherwise, the installation may fail with the following error:

Setup failed to start on the remote machine. Check the Task Scheduler event log on the remote machine.

Please refer to this Knowledge Base article for more information.

I get this error every now and then and usually can't remember how to resolve it. Maybe I'll be able to find my own blog entry when I search on the error!

Purging Database Mail data from msdb

Tara Kizer — Mon, 28 Apr 2008 23:04:19 GMT

On Sunday morning, I got paged by one of our monitoring systems that we were low on free disk space on one of our production servers. The specific resource that was low on free disk space was our "Backup" mount point. Since I didn't think this should be the case for a few more months, I looked into each folder to see if any database backup was larger than it should be. That's when I noticed that our msdb backups were 6 gigabytes in size.

Typically the msdb database is larger than it should be due to backup history, but we already have a job to purge that data. The job was successful the last time it ran, so I decided to find out if there were any other tables that had an unusual amount of data in them. SQL Server 2005 makes this easy for us by providing the "Disk Usage by Top Tables" report in Management Studio. When I viewed this report, I noticed that the sysmail_attachments system table was at the very top. It showed that the table was consuming 6 gigabytes of space.

The sysmail_attachments system table is used by Database Mail to store the email attachments. We have a job that runs hourly that sends an email with an attachment to several people. The table only had a few thousand rows in it, but it took several minutes to delete everything that was older than a couple of days. While the delete was running, I checked Books Online to see if there was a system stored procedure to do the purge or if I was going to need to write my own. I found sysmail_delete_mailitems_sp.

If you send attachments via Database Mail, I would recommend that you create a job that runs sysmail_delete_mailitems_sp on a scheduled basis, perhaps daily or weekly. This recommendation can also be found in Books Online in the "Remarks" section of the "sysmail_delete_mailitems_sp" topic.

Here is an example of what to put in the job step:

DECLARE @d datetime

SET @d = DATEADD(dd, -5, GETDATE())

EXEC msdb.dbo.sysmail_delete_mailitems_sp @sent_before = @d

CLR stored procedure to get disk space information

Tara Kizer — Tue, 18 Dec 2007 23:45:32 GMT

I've seen lots of tools/scripts to get disk space information about a particular SQL Server, but none of them include the information about mount points. Mount points are now supported in SQL Server 2005. We implemented them on our production clusters and therefore needed a way to monitor them. We are now monitoring them with MOM via a Veritas management pack, but before that was implemented we used a CLR stored procedure that I wrote. It is written in C#.

The code allows you to get disk space information for the local server or for remote servers. You just need to pass the hostname to the stored procedure.

NOTE: I didn't get a chance to add error handling to this. I'd love to hear your suggestions on how better to write this, but please be respectful. I'm only a DBA!

C# code:

using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using System.Diagnostics;
using Microsoft.SqlServer.Server;

public partial class StoredProcedures
{
    [Microsoft.SqlServer.Server.SqlProcedure]
    public static void isp_DiskSpace(string serverName)
    {
        if (serverName == "")
        {
            serverName = Environment.MachineName;
        }

        PerformanceCounterCategory pcc = new PerformanceCounterCategory("LogicalDisk", serverName);

        SqlDataRecord record = new SqlDataRecord(
            new SqlMetaData("Drive/MountPoint", SqlDbType.NVarChar, 256),
            new SqlMetaData("Capacity (MB)", SqlDbType.VarChar, 256),
            new SqlMetaData("Used Space (MB)", SqlDbType.VarChar, 256),
            new SqlMetaData("Free Space (MB)", SqlDbType.VarChar, 256),
            new SqlMetaData("Percent Free Space", SqlDbType.VarChar, 6));

        SqlContext.Pipe.SendResultsStart(record);

        foreach (string instanceName in pcc.GetInstanceNames())
        {
            PerformanceCounter pcPercentFree = new PerformanceCounter("LogicalDisk", "% Free Space", instanceName, serverName);
            PerformanceCounter pcFreeMbytes = new PerformanceCounter("LogicalDisk", "Free Megabytes", instanceName, serverName);

            float percentfree = pcPercentFree.NextValue();
            float freespace = pcFreeMbytes.NextValue();
            float capacity = (freespace * 100) / percentfree;
            float usedspace = capacity - freespace;

            if (instanceName != "_Total")
            {
                record.SetSqlString(0, instanceName);
                record.SetSqlString(1, capacity.ToString());
                record.SetSqlString(2, usedspace.ToString());
                record.SetSqlString(3, freespace.ToString());
                record.SetSqlString(4, percentfree.ToString());
                SqlContext.Pipe.SendResultsRow(record);
            }
        }
        SqlContext.Pipe.SendResultsEnd();
    }
};

Once you've compiled the code into a DLL, run the below to get it setup inside SQL Server.

T-SQL code:

USE master
GO

EXEC sp_configure 'show advanced options', 1
RECONFIGURE
EXEC sp_configure 'clr enabled', 1
RECONFIGURE

ALTER DATABASE Admin SET TRUSTWORTHY ON
GO

USE Admin
GO

CREATE ASSEMBLY DiskSpace 
FROM 'C:\SQLTools\DiskSpace.dll'
WITH PERMISSION_SET = UNSAFE
GO

CREATE PROC dbo.isp_DiskSpace @serverName nvarchar(4000)
WITH EXECUTE AS CALLER
AS
EXTERNAL NAME DiskSpace.StoredProcedures.isp_DiskSpace
GO

Example calls:

--local server
EXEC dbo.isp_DiskSpace @serverName = ''

EXEC dbo.isp_DiskSpace @serverName = 'LocalServer'


--remote server
EXEC dbo.isp_DiskSpace @serverName = 'RemoteServer'