First published on MSDN on Apr 15, 2013
I know this is a fairly common problem and there might be multiple solutions out there, but I figured adding another one may not hurt.
An application I was supporting recently, was leading to 100s of GB of transaction log growth in spurts and we needed to discover what was causing the growth. I built the following process to help with the discovery:
1. Create a script titled FindLargeTransactions.sql and paste the following contents into it:
set nocount on
go
declare @datetime datetime
select @datetime = GETDATE()
select @datetime logtime, text, tr.database_id, tr.transaction_id, database_transaction_log_bytes_used, database_transaction_log_bytes_reserved,
database_transaction_log_record_count, database_transaction_state, database_transaction_status,
database_transaction_log_bytes_used_system, database_transaction_log_bytes_reserved_system
from sys.dm_tran_database_transactions tr
inner join sys.dm_exec_requests r
on tr.transaction_id = r.transaction_id
cross apply sys.dm_exec_sql_text(sql_handle)
where database_transaction_log_bytes_used > 100*1024*1024 -- 100 MB
2. Schedule a job that runs this SQLCMD.EXE every 1 minute for example. Make sure you choose an output file for the job step; this is where the contents of this script will be saved.
sqlcmd -SmyServer\sql2008r2 -E -ic:\temp\FindLargeTransactions.sql -W -w65535 - s"|" -h-1 -HFindLargeTransactions
3. Then, create a table and into which you can BULK INSERT the data for further analysis .
drop table [dbo].[LargeTransactions]
go
CREATE TABLE [dbo].[LargeTransactions](
[logtime] datetime not null,
[text] [nvarchar](max) NULL,
[database_id] [int] NOT NULL,
[transaction_id] [bigint] NOT NULL,
[database_transaction_log_bytes_used] [bigint] NOT NULL,
[database_transaction_log_bytes_reserved] [bigint] NOT NULL,
[database_transaction_log_record_count] [bigint] NOT NULL,
[database_transaction_state] [int] NOT NULL,
[database_transaction_status] [int] NOT NULL,
[database_transaction_log_bytes_used_system] [int] NOT NULL,
[database_transaction_log_bytes_reserved_system] [int] NOT NULL
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
4. Identify the job output file and replace in the following script as the BULK INSERT source. Execute the BULK INSERT command
BULK INSERT dbo.LargeTransactions FROM 'c:\temp\FindLargeTransactions_10_29_2012.out'
WITH
(
FIELDTERMINATOR ='|'
)
5. Query the table for “large” transactions, i.e. ones that impact the transaction log severely.
select database_transaction_log_bytes_used/1024/1024 LogMBUsed, Text
from LargeTransactions
order by 1 desc
Namaste!
Joseph
