Maintennce Job step to shrink the transaction log on every db ~ dynamic SQL

  • Hi One & All...

    Trying to get a create a nightly job to srink the transaction log for all dbs on a server.

    Using the below SQL .. whilst it will return the logname it will not "use it" in the dbcc shrbinkfile statement.

    Are there altenrtive methods to do this ? Am I on the right track etc and if so what do I need to change

    DECLARE

    @dbname varchar(255),

    @parentname varchar(255),

    @SQLSTR VARCHAR (1500),

    @ctrl CHAR (2),

    @dbversion varchar(10),

    @logname varchar(50)

    SET @ctrl = CHAR (13) + CHAR (10)

    DECLARE DBCUR CURSOR FOR

    select name

    where name like '%cust%'

    order by 1

    OPEN DBCUR

    FETCH NEXT FROM DBCUR INTO @dbname

    WHILE @@FETCH_STATUS = 0

    BEGIN

    set @sqlstr =

    'use '+@dbname +@ctrl

    +'declare@logname varchar(50),'+@ctrl

    +'@filenumber int,'+@ctrl

    +'@sqlstr2varchar(1000)'+@ctrl

    +'select @logname = name from '+@dbname+'..sysfiles where fileid = 2'+@ctrl

    +'select @logname = name from sysfiles where fileid = 2'+@ctrl

    +'ALTER DATABASE ' + @dbname +' SET RECOVERY SIMPLE WITH NO_WAIT'+@ctrl

    +'print @logname'+@ctrl

    +'DBCC SHRINKFILE ('+@logname+',TRUNCATEONLY)'+@ctrl

    +'ALTER DATABASE ' + @dbname +' SET FULL SIMPLE WITH NO_WAIT'+@ctrl

    exec (@sqlstr)

    FETCH NEXT FROM DBCUR INTO @dbname

    END

    CLOSE DBCUR

    DEALLOCATE DBCUR

    GO

    many thanks

    Simon

  • Simon_L (11/1/2010)


    Trying to get a create a nightly job to srink the transaction log for all dbs on a server.

    Why? Unless this is a dev/test server, this is a really, really bad idea.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • yep just dev/test servers and log space can run away with itself .. not a "real" one 🙂

  • Why not just set the databases to simple recovery mode, and leave them like that?

  • Ok, few comments...

    Unless you have cases of DBs with more than one log, forget the log file name and just use the fileID. It will be 2 for the log file. It's easier than trying to ID the filename and concatenate it in with the right quotes

    Truncateonly is not a valid option for log files, as per Books Online:

    TRUNCATEONLY

    Releases all free space at the end of the file to the operating system but does not perform any page movement inside the file. The data file is shrunk only to the last allocated extent.

    TRUNCATEONLY is applicable only to data files.

    Remove that and replace with a target size.

    No_Wait is not required for setting recovery models. They're done immediately regardless.

    ALTER DATABASE ' + @dbname +' SET FULL SIMPLE WITH NO_WAIT'

    This isn't going to work at all. I assume you meant SET RECOVERY SIMPLE, but you did that at the beginning, so no need to do it again.

    sysfiles is deprecated, should not be used for new development and will be removed in a future version of SQL. Use sys.database_files or sys.master_files instead.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • If this is for Dev/QA/sandboxes, then the following code should work for you. It sets the database to simple, and shrinks both the log and data files. It's not elegant, but it works.

    We have set up nightly restore jobs that restore the production data to testing/qa/etc. databases. Disk space is always an issue on these boxes, so we have implemented this in addition to a number of other things to keep this in check.

    To repeat the words of a previous post, don't do this on a production system. It's senseless.

    SET NOCOUNT ON

    DECLARE @DB sysname

    DECLARE @Name varchar(100)

    DECLARE @Recovery varchar(100)

    DECLARE @sql varchar(MAX)

    SET @sql = ''

    DECLARE db_cur CURSOR FOR

    SELECT name

    FROM master..sysdatabases

    OPEN db_cur

    FETCH NEXT FROM db_cur INTO @DB

    WHILE @@FETCH_STATUS = 0 BEGIN

    SELECT @Recovery = CONVERT(varchar(max), DATABASEPROPERTYEX(@DB, 'Recovery'))

    IF @Recovery <> 'SIMPLE' AND @DB <> 'tempdb' BEGIN

    SET @sql = 'ALTER DATABASE [' + @DB + '] SET RECOVERY SIMPLE'

    --PRINT @sql

    EXEC (@SQL)

    End

    DECLARE FileCur INSENSITIVE CURSOR FOR

    SELECT name

    --physical_name

    FROM sys.master_files

    WHERE database_id = DB_ID(@DB)

    OPEN FileCur

    FETCH NEXT FROM FileCur INTO @Name

    WHILE @@FETCH_STATUS = 0 Begin

    SET @sql = 'USE [' + @DB + '] DBCC SHRINKFILE (N' + QUOTENAME(@Name, '''') + ' , 0, TRUNCATEONLY)'

    --Print @sql

    EXEC (@SQL)

    FETCH NEXT FROM FileCur INTO @Name

    END

    Close FileCur

    DEALLOCATE FileCur

    FETCH NEXT FROM db_cur INTO @DB

    END

    CLOSE DB_CUR

    DEALLOCATE db_cur

    Michael L John
    If you assassinate a DBA, would you pull a trigger?
    To properly post on a forum:
    http://www.sqlservercentral.com/articles/61537/

  • that looks just the ticket with its nested cursor to work out the logfile names

    I've added the caveat that "file_id = 2" and will have a further play

    thank you all for your advice and help

    muchly appreciated

    ~Simon

  • Simon_L (11/1/2010)


    that looks just the ticket with its nested cursor to work out the logfile names

    I've added the caveat that "file_id = 2" and will have a further play

    Just change the shrink so that it doesn't use the TruncateOnly option, which is ignored for log files.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • Michael L John (11/1/2010)


    SELECT name

    FROM master..sysdatabases

    sysdatabases is deprecated, should not be used in new development and will be removed from a future version of the product.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • thank you Gail 🙂

  • Also, don't shrink to 0. Shrink to what you know to be a reasonable size for the databases.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • so based on all your feedback Ive slightly altered Michael's script and I now have :

    SET NOCOUNT ON

    DECLARE @DBsysname,

    @Namevarchar(100),

    @Recoveryvarchar(100),

    @sqlvarchar(MAX)

    SET @sql = ''

    DECLARE db_cur CURSOR FOR

    SELECT name

    FROM master.sys.databases

    wherename like '%cust%'

    order by 1

    OPEN db_cur

    FETCH NEXT FROM db_cur INTO @DB

    WHILE @@FETCH_STATUS = 0 BEGIN

    SELECT @Recovery = CONVERT(varchar(max), DATABASEPROPERTYEX(@DB, 'Recovery'))

    IF @Recovery <> 'SIMPLE'

    BEGIN

    SET @sql = 'ALTER DATABASE [' + @DB + '] SET RECOVERY SIMPLE'

    EXEC (@SQL)

    End

    DECLARE FileCur INSENSITIVE CURSOR FOR

    SELECT name

    FROM sys.master_files

    WHERE database_id = DB_ID(@DB)

    AND file_id = 2

    OPEN FileCur

    FETCH NEXT FROM FileCur INTO @Name

    WHILE @@FETCH_STATUS = 0 Begin

    SET @sql = 'USE [' + @DB + '] DBCC SHRINKFILE (N' + QUOTENAME(@Name, '''') + ' , 50)'

    EXEC (@SQL)

    FETCH NEXT FROM FileCur INTO @Name

    END

    Close FileCur

    DEALLOCATE FileCur

    SET @sql = 'ALTER DATABASE [' + @DB + '] SET RECOVERY FULL'

    EXEC (@SQL)

    FETCH NEXT FROM db_cur INTO @DB

    END

    CLOSE DB_CUR

    DEALLOCATE db_cur

    go

  • Why are you setting the recovery back to full? You've said this is just a dev/test server and, since you're willing to break the log chains I assume there's no log backups or point-in-time recovery, so why not just leave them in simple Recovery?

    If you set to full and you have no log backups, that'll be a major cause of the growing logs.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • I asked a similar question a while back

    http://www.sqlservercentral.com/Forums/Topic963333-391-1.aspx#bm964094

    EXEC sp_MSforeachdb 'DECLARE @ln varchar(100) SET @ln=(SELECT name FROM [?].dbo.sysfiles WHERE fileid=2) USE [?] DBCC SHRINKFILE (@ln, 0)'

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