Log Reservation

/********** SQL Server Transaction Log Management->Chapter2 **********/
--Listing 2.1:  Re-creating the TestDB database, plus PrimaryTable_Large
USE master ; 
 
IF DB_ID(‘TestDB‘) IS NOT NULL  
    DROP DATABASE TestDB ; 
 
CREATE DATABASE TestDB ON PRIMARY  
 (   NAME = N‘TestDB‘ 
   , FILENAME = N‘D:\SQLData\TestDB.mdf‘ 
   , SIZE = 199680KB 
   , FILEGROWTH = 16384KB 
 ) 
 LOG ON 
 (   NAME = N‘TestDB_log‘ 
   , FILENAME = N‘D:\SQLData\TestDB_log.ldf‘ 
   , SIZE = 2048KB 
   , FILEGROWTH = 16384KB 
 ); 
GO 
 
USE TestDB 
Go 
IF OBJECT_ID(‘dbo.PrimaryTable_Large‘, ‘U‘) IS NOT NULL  
    DROP TABLE dbo.PrimaryTable_Large 
GO 
CREATE TABLE PrimaryTable_Large 
    ( 
      ID INT IDENTITY 
             PRIMARY KEY , 
      SomeColumn CHAR(4) NULL , 
      Filler CHAR(1500) DEFAULT ‘‘ 
    ); 
GO 
 
ALTER DATABASE TestDB SET RECOVERY FULL;

/*Initial full database backup of TestDB*/ 
BACKUP DATABASE TestDB 
TO DISK =‘D:\SQLBackups\TestDB.bak‘ 
WITH INIT; 
GO 
 
DBCC SQLPERF(LOGSPACE) ; 
/*Log Size (MB): 2, Log Space used (%): 18*/

--检查恢复模式
SELECT NAME,recovery_model_desc FROM sys.databases WHERE NAME=‘TestDB‘
--last_log_backup_lsn为空则处于自动截断模式
SELECT DB_NAME(database_id) AS DatabaseName,last_log_backup_lsn
FROM master.sys.database_recovery_status WHERE database_id=DB_ID(‘TestDB‘)

--Listing 2.2:  Four VLFs in the newly created TestDB database.
-- how many VLFs? 
USE TestDB; 
GO 
DBCC Loginfo 
GO

--Listing 2.3:  VLFs after adding 1,500 rows.
USE TestDB; 
GO 
INSERT  INTO PrimaryTable_Large 
        ( SomeColumn, Filler 
        ) 
        SELECT TOP 1500 
                ‘abcd ‘, 
                REPLICATE(‘a‘, 200)  
        FROM    msdb.sys.columns a 
                CROSS JOIN msdb.sys.columns b 
GO 
 
DBCC SQLPERF(LOGSPACE) ;
/*Log Size: 18 MB ; Log Space Used: 16%*/ 
 
DBCC Loginfo 
GO

--Listing 2.4:  VLF usage after log backup.
/*now a log backup*/ 
BACKUP Log TestDB 
TO DISK =‘D:\SQLBackups\TestDB_log.bak‘ 
WITH INIT; 
GO 
 
DBCC SQLPERF(LOGSPACE) ; 
/*Log Size: 18 MB ; Log Space Used: 6%*/ 
 
-- how many VLFs?  
USE TestDB; 
GO 
DBCC Loginfo 
GO

BEGIN TRAN
INSERT  INTO PrimaryTable_Large 
        ( SomeColumn, Filler 
        ) 
        SELECT TOP 15000 
                ‘abcd ‘, 
                REPLICATE(‘a‘, 200)  
        FROM    msdb.sys.columns a 
                CROSS JOIN msdb.sys.columns b
--COMMIT TRAN 

USE TestDB 
GO 
SELECT DTST.[session_id],
       --DES.[login_name] AS [Login Name],
       DB_NAME(DTDT.database_id)  AS [Database],
       DTDT.[database_transaction_begin_time] AS [Begin Time],
       DATEDIFF(ms, DTDT.[database_transaction_begin_time], GETDATE()) AS [Duration ms],
       CASE DTAT.transaction_type
            WHEN 1 THEN ‘Read/Write‘
            WHEN 2 THEN ‘Read-Only‘
            WHEN 3 THEN ‘System‘
            WHEN 4 THEN ‘Distributed‘
       END                        AS [Transaction Type],
       CASE DTAT.transaction_state
            WHEN 0 THEN ‘Not fully initialized‘
            WHEN 1 THEN ‘Initialized, not started‘
            WHEN 2 THEN ‘Active‘
            WHEN 3 THEN ‘Ended‘
            WHEN 4 THEN ‘Commit initiated‘
            WHEN 5 THEN ‘Prepared, awaiting resolution‘
            WHEN 6 THEN ‘Committed‘
            WHEN 7 THEN ‘Rolling back‘
            WHEN 8 THEN ‘Rolled back‘
       END                        AS [Transaction State],
       DTDT.[database_transaction_log_record_count] AS [Log Records],
       DTDT.[database_transaction_log_bytes_used] AS [Log Bytes Used],
       DTDT.[database_transaction_log_bytes_reserved] AS [Log Bytes Reserved],
       DEST.[text] AS [Last Transaction Text],
       DEQP.[query_plan] AS [Last Query Plan]
FROM   sys.dm_tran_database_transactions DTDT
       INNER JOIN sys.dm_tran_session_transactions DTST
            ON  DTST.[transaction_id] = DTDT.[transaction_id]
       INNER JOIN sys.[dm_tran_active_transactions] DTAT
            ON  DTST.[transaction_id] = DTAT.[transaction_id]
       INNER JOIN sys.[dm_exec_sessions] DES
            ON  DES.[session_id] = DTST.[session_id]
       INNER JOIN sys.dm_exec_connections DEC
            ON  DEC.[session_id] = DTST.[session_id]
       LEFT JOIN sys.dm_exec_requests DER
            ON  DER.[session_id] = DTST.[session_id]
       CROSS APPLY sys.dm_exec_sql_text (DEC.[most_recent_sql_handle]) AS DEST 
       OUTER APPLY sys.dm_exec_query_plan (DER.[plan_handle]) AS DEQP
WHERE  DB_NAME(DTDT.database_id) = ‘TestDB‘
ORDER BY
       DTDT.[database_transaction_log_bytes_used] DESC; 
--ORDER BY [Duration ms] DESC; 

--简单点使用这个
SELECT  d.name ,
        --session_id ,
        d.recovery_model_desc ,
        --database_transaction_begin_time ,
        database_transaction_log_record_count ,
        database_transaction_log_bytes_used ,
        database_transaction_log_bytes_reserved ,
        DATEDIFF(ms, database_transaction_begin_time, GETDATE())
                AS [Duration ms]
FROM    sys.dm_tran_database_transactions AS dt
        INNER JOIN sys.dm_tran_session_transactions AS st
               ON dt.transaction_id = st.transaction_id
        INNER JOIN sys.databases AS d ON dt.database_id = d.database_id
WHERE d.name = ‘TestDB‘