SQL Server – Unable to shrink Transaction Log file

Background

Received an alert stating that we have gotten below our threshold of 10% on one of DB Servers.

Thanks goodness no late night phone calls.

Only saw it coming to work this morning.

The good and bad about smartphone.

TroubleShooting

Windows Desktop

Folder

Image

Explanation

  1. ppsivr_8.ldf is 28 GB

SQL Metadata

Outline

Here are dynamic management views ( DMVs) that we will access…

  1. dbcc sqlperf(logspace)
  2. sys.database_files
  3. sys.databases
  4. sys.dm_exec_requests & sysprocesses

 

Review Transaction Log File Sizes

SQL


dbcc sqlperf(logspace)

Output

 

Explanation

  1. ppsivr
    • Log Size MB
      • 27,699 MB
      • 27 GB

Review Database File Sizes

SQL


-- replace with targeted database
use [database]

SELECT 
		  [name]

		, [type]
			= tblSDF.[type_desc]

		, [filename]
			= tblSDF.[physical_name]

		, [allocatedMB]
			= tblSDF.size / 128

		, [usedMB]
			= CAST(FILEPROPERTY(name, 'SpaceUsed') AS int)
				/ 128

		, [availableSpaceMB]
				 = ( size - CAST(FILEPROPERTY(name, 'SpaceUsed') AS int) )
					/ 128

FROM sys.database_files tblSDF

order by
		tblSDF.size desc
;

Output

Review Database Transaction Log Re-usability State

SQL


declare @dbid   int
declare @dbname sysname

set @dbname = 'ppsivr'
set @dbid = db_id(@dbname)

select 
		    tblSD.[database_id]
		  , tblSD.[name]
		  , tblSD.[log_reuse_wait_desc]

from   sys.databases tblSD

where  (
			   (@dbid is null)

			or ( tblSD.[database_id] = @dbid)
		
	   )

Output

Explanation

  1. log_reuse_wait_desc
    • The database is not re-cycling its transaction log due to an ‘Active Transaction’

Review Current DB Requests

Code



declare @dbid   int
declare @dbname sysname

set @dbname = 'ppsivr'
set @dbid = db_id(@dbname)

select 
		  tblSDER.[session_id]

		, [database] 
			= db_name(tblSDER.[database_id])

		, [openTransaction]
			= tblSP.[open_tran]

		, tblSDER.[status]

		, tblSDER.[command]

		, tblSDER.[percent_complete]

		, tblSDER.wait_type

		, tblSDER.last_wait_type

		, tblSDER.[reads]

		, tblSDER.[writes]

from   sys.dm_exec_requests tblSDER

inner join master..sysprocesses tblSP

	on tblSDER.[session_id] = tblSP.[spid]

where  (

	         ( tblSDER.[open_tran] != 0 )

	      or ( tblSDER.[database_id] = @dbid)

      )



Output

Explanation

  1. User Transactions
    • It does not appear that we have user transactions that are current using our targeted database
  2. Background
    • WAIT_XTP_OFFLINE_CKPT_NEW_LOG
      • It does does not apply that WAIT_XTP_OFFLINE_CKPT_NEW_LOG updates the percent_complete column as so it is a bit difficult to track its current progress

 

Remediation

Here are the things we tried:

  1. dbcc shrinkfile
  2. Take database offline and bring back online

Attempt to Shrink Transaction Log Files

SQL


use [ppsivr]
go

dbcc shrinkfile('ppsivr_log')
go

Output

Explanation

  1. We want to take a good look at Current Size and Used Pages
    • In our case they are same
    • What is in our Transaction Log File?

 

Take Database Offline and bring it back online

Force termination of ongoing sessions

SQL


use master
go

ALTER DATABASE [ppsivr]
	SET SINGLE_USER WITH ROLLBACK IMMEDIATE
	;

alter database [ppsivr] set offline;

alter database [ppsivr] set online;

ALTER DATABASE [ppsivr]
	SET MULTI_USER WITH ROLLBACK IMMEDIATE
	;

 

Summary

But, nothing worked!

We will come back and talk about what worked.

References

  1. Microsoft
    • Support.Microsoft.com
      • FIX: Offline checkpoint thread shuts down without providing detailed exception information in SQL Server 2014
        Link

SQL Server – Transaction Log Management – Recovery Mode

Background

It is finally time to revisit a blog posting I started on Dec 21st, 2016.

That post is titled “SQL Server – Error – Cannot shrink log file because the logical file located at the end of the file is in use“.

And, it is here.

Issue

Received an alarm that our database files are growing and so sought to find out why.

 

TroubleShooting

Transaction Log – Utilization Metrics from Performance Counter

transactionLog.IUDF_UtilizationMetricsFromPerformanceCounters

Code

use master
go

if schema_id('transactionLog') is null
begin

	exec('create schema [transactionLog] authorization [dbo]')

end
go

if object_id('[transactionLog].[IUDF_UtilizationMetricsFromPerformanceCounters]') is null
begin

	exec(
			'create function [transactionLog].[IUDF_UtilizationMetricsFromPerformanceCounters]
			()
			RETURNS table
			AS
			RETURN 
			(
				SELECT 
					[shell] = 1/0
		   );
	   	   '
		)

end
go


alter function [transactionLog].[IUDF_UtilizationMetricsFromPerformanceCounters]
()
returns TABLE
as
return
(

	with cte
	(
		  [dbid]
		, [database]
		, [counter]
		, [size]
	)
	as
	(
 
		SELECT
				  [dbid]
					= db_id(RTRIM(instance_name)) 
 
				, [database]
					= RTRIM(instance_name) 
 
				, tblDMOPC.counter_name
 
				, cntr_value log_size_kb
 
		FROM  sys.dm_os_performance_counters tblDMOPC
 
		WHERE tblDMOPC.object_name = 'SQLServer:Databases'
 
		AND   tblDMOPC.counter_name like 'Log File' + '%'
 
		AND   tblDMOPC.instance_name <> '_Total'
 
	)
	, ctePivot
	as
	(
		select *
 
		from   cte
		pivot 
				(
					avg ([size]) 
							for [counter] in
								(
									  [Log File(s) Used Size (KB)]                                                                                                           
									, [Log File(s) Size (KB)]                                                                                                           
								)
				) as avgSize
 
	)
 
	select 

			  [cteP].[dbid]

			, [cteP].[database]
 
			, [usedMB] = [Log File(s) Used Size (KB)]
							/ 1000
 
			, [totalMB] =  [Log File(s) Size (KB)]
							/ 1000
 
			, [%]
				= cast
					(
						( [Log File(s) Used Size (KB)] * 100.00)
						/ ( [Log File(s) Size (KB)])
						as decimal(10,2 )
					)

			, [recoveryModel]
				= tblSD.recovery_model_desc

			, [log reuse wait]
				= tblSD.log_reuse_wait_desc
			
	from   ctePivot cteP

	inner join sys.databases tblSD

		on cteP.[dbid] = tblSD.database_id
 

)
go


Output

qa_20170207_0958pm

Explanation

  1. Before capturing the screenshot above, our target database, QA_rbpivr1, was in FULL RECOVERY
    • It’s transaction log size was 8 GB
    • And, 3.2 GB of the 8GB is in use

 

Why so much Transaction Log is being held up?

Recovery Mode

Again for QA_rbpiv1  3.2 GB is being used.

Let us review how database is configured

qa_recoverymode_20170207_1009am

We see that the Recovery Mode for our database is Full.

Backup Dates

databaseproperty_options_general_backupdate_qa_20170207_1013am

 

Explanation
  1. The last full backup was taken last night Feb 2nd, 2017 and it completed at 8:35 PM
  2. And, the last Transaction backup was taken on Sunday Feb 5th, 2017 at 6 PM

 

 

Transaction Backup History

Let us review our Transaction Backup History

 

sqlserveragent_transactionbackuphistory_qa_20170207_1019am

Explanation:

  1. Before today, transaction backups were occurred on 2/5/2017, 1/29/2017, 1/22/2017
  2. And, they were occurring each hour
  3. Looked back at the Calendar and those days fell on Sundays

 

 

Review Scheduled Transaction Backup

jobproperties-databasebackup-userdatabases-log-schedules-sunday-eachhour

 

Explanation:

  1. Schedule is Weekly on Sundays
  2. And, the frequency is each hour

 

Correction

Our bad.

Revise Schedule

sqlserveragent_transactionbackuphistory_qa_20170207_1028am

Explanation:

  1. Changed Schedule’s frequency from Weekly to Daily

 

Metadata

Review Checkpoints in Error Log File

Enable Logging of Checkpoints in ErrorLog file

Enable Trace Flags

Code

dbcc traceon (3502, 3504, 3605, -1 )

Review

Code

dbcc tracestatus

Output

dbcctracestatus

Review ErrorLog file

Let us review our error logs and make sure that Checkpoints are indeed been logged.

logfileviewer_20170207_1220pm

 

transactionLog.sp_checkPointsInErrorLogFileAggregate

 

Code

 


use [master]
go

if object_id('transactionLog.sp_checkPointsInErrorLogFileAggregate') is null
begin

	exec('create procedure [transactionLog].[sp_checkPointsInErrorLogFileAggregate] as ')

end
go

alter procedure [transactionLog].[sp_checkPointsInErrorLogFileAggregate] 
as  

begin

	set nocount on;
  
	declare @p1  INT
	declare @p2  INT
	declare @p3  VARCHAR(255)
	declare @p4  VARCHAR(255)
  
	declare @tblErrorLog     TABLE
	(
		  [id] int not null
			identity(1,1)
  
		, [LogDate] datetime
  
		, [ProcessInfo] sysname
  
		, [Text]        varchar(600) null
  
		, primary key
			(
				  [LogDate]
				, [id]
			)
  
		, INDEX INDX_ID
			(
				[id]
			)
  
	)
  
	set @p1 = 0 -- current
	set @p2 = 1 -- error log
	set @p3 = 'Ckpt'
	set @p3 = 'Ckpt dbid'
	set @p4  = ''
  
	insert into @tblErrorLog
	(
		  [LogDate]
		, [ProcessInfo]
		, [Text]        
	)
	exec [sys].[sp_readerrorlog]
			 @p1   = @p1  
		   , @p2   = @p2
		   , @p3   = @p3
		   , @p4   = @p4
  
  
	select
			  tblSD.[name]
  
			, tblSD.log_reuse_wait_desc
  
			, [count] 
				= count(tblEL.LogDate)
  
			, [LogDateMin]
				= min(tblEL.LogDate)
  
			, [LogDateMax]
				= max(tblEL.LogDate)
   
	from  sys.databases tblSD
  
	left outer join @tblErrorLog tblEL
  
			on   tblEL.[Text]  like '%' + cast(tblSD.database_id as varchar(10)) + '%'
          
			and  tblEL.[Text] like 'Ckpt dbid ' + '%' + 'started'
 
	group by
  
			   tblSD.[name]
			 , tblSD.log_reuse_wait_desc
  
	order by
  
			   tblSD.log_reuse_wait_desc asc
			 , count(tblEL.LogDate) desc
			 , tblSD.[name]

end
go



 

Output

errorlogfile_checkpoints_transactionlogcheckpoint_20170207_1036am

Explanation

  1. Database
    • QA_rbpivr1
      • LogDateMax
        • From digging in the Transaction Log File, we can see that the last Transaction Log on 2017-02-06 20:34
        • The timeline is Yesterday, Monday Feb 6th, 2017 8:34 PM
      • LogDateMin
        • LogDateMin is 2017-01-15 04:00
        • In readable term Jan 15th, 2017 @ 4 AM

 

Source Control

GitHub

  1. DanielAdeniji/SQLServerTransactionLogMetrics
    Link

 

Summary

In summary, our transaction size is growing and not being pruned because unfortunately our scheduled Transaction backup job was incorrectly set to only occur on Sundays.

Please keep in mind this only affects databases set for FULL RECOVERY.

From the metrics above, we can see that our identified database Transaction Log Checkpoints are only occurring at the tail end of Full Backups.

And, as aforementioned on Sundays.

 

Microsoft – SQL Server – Log File Utilization and Running Total

Here are I am taking a good look at Database Log File Sizes. And, needing a good
way to determine the overall running total.

I think I can use “dbcc sqlperf(logspace)”.

But, as I had a working code already, I chose to use that one.

The working code basically reads through sys.database_files and uses the MetaData function fileProperty.

The only thing missing is a good path to arriving at running total.

So Googled for one and ended up a finding a good one in very quick succession.

Give Credit to Mike Forman
http://stackoverflow.com/questions/860966/calculate-a-running-total-in-sqlserver

The APPLY operator in SQL 2005 and higher works for this:

select
    t.id ,
    t.somedate ,
    t.somevalue ,
    rt.runningTotal
from TestTable t
 cross apply (
               select sum(somevalue) as runningTotal
    	       from TestTable
    	       where somedate <= t.somedate
    	     ) as rt
order by t.somedate

Giving credit to Mikael Erikson
http://stackoverflow.com/questions/860966/calculate-a-running-total-in-sqlserver

In SQL Server 2012 you can use SUM() with the OVER() clause.

select
    id,
    somedate,
    somevalue,
    sum(somevalue) 
       over(order by somedate rows
             unbounded preceding
           ) as runningtotal
from TestTable

It reminds me of the song that talks about:

  • You ‘re not supposed to say the Word Cancer in a song
  • And, telling Folks that Jesus is the answer, can rub them wrong
  • Well, you like to drink a cold one on the weekend
  • Do you wanna say I am sorry, but don’t know how
  • (King) George Strait – Amarillo by the Morning
  • Tammy Wynette’s – Stand by your Man (re-birth by Hillary Clinton)

During the 44th Country Music (heard on Nov 2010) Award the Artist who sang it had this to say:

I wanna talk to the fans.  It sounds like a cliche when you say thanks to the fans.

The great thing about country fans is, when you say fans, I don’t even mean mine. You guys are loyal to everyone in this room. It’s the most amazing loyal fan base in the world.

Here is a sample code to get SQL Server Transaction Log File Sizes:

select 
      file_id as fileID  
   --, name 
   --, physical_name
   , (size / 128) as sizeInMB
   , (((FILEPROPERTY(name, 'spaceUsed'))) / 128) as spaceUsedInMB    , tblDBFileInUsedRT.spaceUsed as spaceusedRunningTotalInMB
   , (( size - (FILEPROPERTY(name, 'spaceUsed'))) / 128) as 
       availInMB
  , tblDBFileAvailRT.avail as availRunningTotalInMB

from    sys.database_files tblDBFile	

cross apply 
  (

  select 
    sum(((FILEPROPERTY(tblDBFileTotal.name, 'spaceUsed'))) / 128)        as spaceUsed	
  from   sys.database_files tblDBFileTotal
  where  (tblDBFileTotal.type = 1)
  and    tblDBFileTotal.file_id <= tblDBFile.file_id

  )	tblDBFileInUsedRT

cross apply 
  (

    select sum(( size - (FILEPROPERTY(name, 'spaceUsed'))) / 128) 
             as avail	
    from   sys.database_files tblDBFileTotal
    where  (tblDBFileTotal.type = 1)
    and    tblDBFileTotal.file_id <= tblDBFile.file_id

  ) tblDBFileAvailRT

where
	(

 	   (tblDBFile.type = 1)

	)

order by tblDBFile.file_id asc

 

The Artist I was referring to is “Brad Paisley”.  And, the video is available @

Brad Paisley – This is Country Music

http://www.youtube.com/watch?v=n_KxM4rU38Q

 

As my Church’s founding pastor likes to say “Give it a little time”.

Hopefully, sooner or later you will have enough respect for what you do and realize that you only have a small window to do it. And, once that dawns on you, you will truly enjoy LIFE more and appreciate and stand behind’s other work.

The silliness of “Java vs .Net”, “Oracle vs MySQL vs SQL Server” starts to give way to what you ‘re trying to do for your paying customers.

References: