Walk through of Microsoft SQL Server Change Data Capture
This sample script walks through some of the Microsoft Change Data Captures functions. Copy and past the script into SQL Server Management Studio and execute each command. Sample output is included in the script. This demo is based on the [AdventureWorksLT2008] database
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USE [AdventureWorksLT2008] GO -- Create Sample table used for CDC Demo CREATE TABLE [SalesLT].[CustomerCDCDemo]( [CustomerID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [dbo].[Name] NOT NULL, [LastName] [dbo].[Name] NOT NULL, [Phone] [dbo].[Phone] NULL, [CreditLimit] Money NULL, [ModifiedDate] [datetime] NOT NULL, CONSTRAINT [PK_CustomerCDCDemo] PRIMARY KEY CLUSTERED ( [CustomerID] ASC ) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [SalesLT].[CustomerCDCDemo] ADD CONSTRAINT [DF_CustomerCDCDemo_ModifiedDate] DEFAULT (getdate()) FOR [ModifiedDate] GO -- Load Sample table with data SET Identity_Insert AdventureWorksLT2008.[SalesLT].[CustomerCDCDemo] ON GO INSERT [SalesLT].[CustomerCDCDemo]( [CustomerID],[FirstName],[LastName],[Phone],[CreditLimit],ModifiedDate) SELECT [CustomerID],[FirstName],[LastName],[Phone],1000,ModifiedDate FROM SalesLT.Customer GO --(847 row(s) affected) |
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use AdventureWorksLT2008 go -- -- Turn on Change Data Capture at the database level -- exec sys.sp_cdc_enable_db -- -- Turn on CDC for the sample [CustomerCDCDemo] table -- created in the Schema Setup script sys.sp_cdc_enable_table @source_schema = N'SalesLT' ,@source_name = N'CustomerCDCDemo' ,@role_name = N'cdc_admin' ,@capture_instance = N'CustomerCredit' --Name used in CDC functions ,@supports_net_changes = 1 ,@index_name = NULL --Captured only required columns ,@captured_column_list = 'CustomerID,FirstName,LastName,Phone,CreditLimit,ModifiedDate' --Store "captured" data on different disk ,@filegroup_name = NULL -- 2 Jobs are automatically created. -- Job 'cdc.AdventureWorksLT2008_capture' started successfully. -- Job 'cdc.AdventureWorksLT2008_cleanup' started successfully. --Next explore System Tables created by CDC SELECT * FROM cdc.change_tables SELECT * FROM cdc.captured_columns SELECT * FROM cdc.index_columns SELECT * FROM cdc.ddl_history SELECT * FROM cdc.CustomerCredit_CT SELECT * FROM cdc.lsn_time_mapping -- DEMO using Change Data Capture functions -- cdc_get_all and cdc_get_net changes use AdventureWorksLT2008 go --=================================================== -- Perform changes to SalesLT.[CustomerCDCDemo] table -- Run each statement one at a time --=================================================== insert into SalesLT.[CustomerCDCDemo] ([FirstName],[LastName],[Phone],[CreditLimit]) values (N'Chris','Skorlinski','803-555-1212',1000) Go -- Update Name update SalesLT.[CustomerCDCDemo] set [FirstName] = N'Christopher' where [Phone] = '803-555-1212' Go -- Update Credit limit update SalesLT.[CustomerCDCDemo] set CreditLimit = 3000 -- from 1000 to 3000 where [Phone] = '803-555-1212' --Show new record with corrected name -- and increased Creditlimit select [CustomerID],[FirstName],[LastName],[Phone],[CreditLimit] from SalesLT.[CustomerCDCDemo] where [Phone] = '803-555-1212' go CustomerID FirstName LastName Phone CreditLimit ----------- ----------------------------------- ----------------------------------- ------------------------- --------------------- 30119 Christopher Skorlinski 803-555-1212 3000.00 (1 row(s) affected) /*=================================================== Use CDC Functions to retrieve history of changes. Can return "current" values or both "current" and "previous" cdc.fn_cdc_get_ALL_changes (@begin_lsn, @end_lsn) cdc.fn_cdc_get_NET_changes (@begin_lsn, @end_lsn) @begin_lsn = the start_lsn value from the cdc.change_tables system table. @end_lsn = the max lsn value in the cdc.change_tables system table. --=================================================== */ declare @begin_lsn binary(10), @end_lsn binary(10) set @begin_lsn = sys.fn_cdc_get_min_lsn('CustomerCredit') set @end_lsn = sys.fn_cdc_get_max_lsn() select [__$start_lsn],[__$operation],[__$update_mask] ,[FirstName],[CreditLimit] from cdc.fn_cdc_get_all_changes_CustomerCredit( @begin_lsn, @end_lsn, 'all') __$start_lsn __$operation __$update_mask FirstName CreditLimit ---------------------- ------------ ------------------------------------- ----------------------------------- --------------------- 0x00000037000003000004 2 0x3F Chris 1000.00 0x00000037000003290004 4 0x02 Christopher 1000.00 0x00000037000003340004 4 0x10 Christopher 3000.00 (3 row(s) affected) /* Row 1 shows the insert; __$operation=2 Row 2 shows the update of the FirstName; __$operation=4 Row 3 shows the update of the CreditLimit; __$operation=4 */ /* If we had 100 columns, how would we tell which was the NEW data? CDC provides helper function to use __$update_mask to identify which column contains the NEW data 0x02 = 00010 = 2nd column = FirstName 0x10 = 10000 = 5th column = CreditLimit */ --=================================================== --What if we needed to see previous values? --=================================================== declare @begin_lsn binary(10), @end_lsn binary(10) set @begin_lsn = sys.fn_cdc_get_min_lsn('CustomerCredit') set @end_lsn = sys.fn_cdc_get_max_lsn() select [__$start_lsn],[__$operation],[__$update_mask] ,[FirstName],[CreditLimit] from cdc.fn_cdc_get_all_changes_CustomerCredit( @begin_lsn, @end_lsn, 'all update old') -- see previous values __$start_lsn __$operation __$update_mask FirstName CreditLimit ---------------------- ------------ ------------------------------------- ----------------------------------- --------------------- 0x00000037000003000004 2 0x3F Chris 1000.00 0x00000037000003290004 3 0x02 Chris 1000.00 0x00000037000003290004 4 0x02 Christopher 1000.00 0x00000037000003340004 3 0x10 Christopher 1000.00 0x00000037000003340004 4 0x10 Christopher 3000.00 (5 row(s) affected) /* Row 1 shows the insert. __$operation=2 Row 2 shows the Previous FirstName. __$operation=3 Row 3 shows the Updated FirstName. __$operation=4 Row 4 shows the Previous CreditLimit. __$operation=3 Row 5 shows the Updated CreditLimit. __$operation=4 */ /*=================================================== Row changed multiple time, but I only want to see final "combined" changes. cdc.fn_cdc_get_net_changes_ Special feature, more overhead, must be enabled when the table is configured for CDC tracking. sys.sp_cdc_enable_table ,@supports_net_changes = 1 --===================================================*/ declare @begin_lsn binary(10), @end_lsn binary(10) set @begin_lsn = sys.fn_cdc_get_min_lsn('CustomerCredit') set @end_lsn = sys.fn_cdc_get_max_lsn() select [__$start_lsn],[__$operation],[__$update_mask] ,[FirstName],[CreditLimit] from cdc.fn_cdc_get_net_changes_CustomerCredit( @begin_lsn, @end_lsn, 'all') __$start_lsn __$operation __$update_mask FirstName CreditLimit ---------------------- ------------ ------------------------------------- ----------------------------------- --------------------- 0x00000037000003340004 2 NULL Christopher 3000.00 (1 row(s) affected) /*=================================================== How can CDC show me what rows were DELETED? __$operation = 1 =====================================================*/ -- delete new Customer delete SalesLT.[CustomerCDCDemo] where [Phone] = '803-555-1212' --fn_cdc_get_all_changes declare @begin_lsn binary(10), @end_lsn binary(10) set @begin_lsn = sys.fn_cdc_get_min_lsn('CustomerCredit') set @end_lsn = sys.fn_cdc_get_max_lsn() select [__$start_lsn],[__$operation],[__$update_mask] ,[FirstName],[CreditLimit] from cdc.fn_cdc_get_all_changes_CustomerCredit( @begin_lsn, @end_lsn, 'all update old') -- see previous values __$start_lsn __$operation __$update_mask FirstName CreditLimit ---------------------- ------------ ------------------------------------- ----------------------------------- --------------------- ... 0x00000038000000390005 1 0x3F Christopher 3000.00 --NOTE: Save the $start_lsn value, -- we'll use that later in the script -- example: 0x00000038000000390005 /*================================================ After DELETE, what happened to NET_changed output? ====================================================*/ declare @begin_lsn binary(10), @end_lsn binary(10) set @begin_lsn = sys.fn_cdc_get_min_lsn('CustomerCredit') set @end_lsn = sys.fn_cdc_get_max_lsn() select [__$start_lsn],[__$operation],[__$update_mask] ,[FirstName],[LastName],[Phone],[CreditLimit] from cdc.fn_cdc_get_net_changes_CustomerCredit( @begin_lsn, @end_lsn, 'all') (0 row(s) affected) -- The NET effect after the Insert, Update, Delete, is 0 change (no rows) /*=================================================== How does CDC Tracking Tables which make this happen [CustomerCredit_CT] -- name supplied when table was enabled. [lsn_time_mapping] -- list transactions and time_stamp for collections =====================================================*/ --[CustomerCredit_CT] populated by background "_capture" job SELECT [__$start_lsn] ,[__$seqval] ,[__$operation] ,[__$update_mask] ,[FirstName] ,[CreditLimit] FROM [cdc].[CustomerCredit_CT] GO __$start_lsn __$seqval __$operation __$update_mask FirstName CreditLimit ---------------------- ---------------------- ------------ ------------------------------------- ----------------------------------- --------------------- 0x00000037000003000004 0x00000037000003000003 2 0x3F Chris 1000.00 0x00000037000003290004 0x00000037000003290002 3 0x02 Chris 1000.00 0x00000037000003290004 0x00000037000003290002 4 0x02 Christopher 1000.00 0x00000037000003340004 0x00000037000003340002 3 0x10 Christopher 1000.00 0x00000037000003340004 0x00000037000003340002 4 0x10 Christopher 3000.00 0x00000038000000390005 0x00000038000000390002 1 0x3F Christopher 3000.00 (6 row(s) affected) --One row for each batch of transactions captured SELECT [start_lsn] -- 0x0000003600000A820005 lsn last capture ,[tran_begin_time] ,[tran_end_time] ,[tran_id] ,[tran_begin_lsn] FROM [cdc].[lsn_time_mapping] start_lsn tran_begin_time tran_end_time tran_id tran_begin_lsn ---------------------- ----------------------- ----------------------- ---------------------- ---------------------- 0x0000003500001ECC004D 2010-09-30 15:39:07.543 2010-09-30 15:39:07.543 0x00 0x00000000000000000000 --insert transaction-- 0x00000037000003000004 2010-09-30 15:41:09.480 2010-09-30 15:41:09.480 0x0000000013EF 0x00000037000003000002 --2 update transactions-- 0x00000037000003290004 2010-09-30 15:41:18.553 2010-09-30 15:41:18.553 0x0000000013F9 0x00000037000003290001 0x00000037000003340004 2010-09-30 15:41:47.767 2010-09-30 15:41:47.767 0x000000001401 0x00000037000003340001 --pause in activity, no data captured-- 0x00000038000000230001 2010-09-30 15:46:50.000 2010-09-30 15:46:50.000 0x00 0x00000000000000000000 ---delete transaction--- 0x00000038000000390005 2010-09-30 15:48:03.493 2010-09-30 15:48:03.493 0x000000001455 0x00000038000000390001 (6 row(s) affected) --================================================== --Run Multiple INSERT/UPDATEs -- --================================================== insert into SalesLT.[CustomerCDCDemo] ([FirstName],[LastName],[Phone],[CreditLimit]) values (N'Erica','Skorlinski','704-555-1212',1000) update SalesLT.[CustomerCDCDemo] set CreditLimit = CreditLimit + 1500 where [CustomerID] <10 -- 2nd update update SalesLT.[CustomerCDCDemo] set CreditLimit = CreditLimit + 50 where [CustomerID] <10 update SalesLT.[CustomerCDCDemo] set CreditLimit = CreditLimit + 3000 where LastName like 'S%' DELETE SalesLT.[CustomerCDCDemo] where LastName like 'L%' --=================================================== --Retrieve changed data --=================================================== declare @begin_lsn binary(10), @end_lsn binary(10) set @begin_lsn = sys.fn_cdc_get_min_lsn('CustomerCredit') set @end_lsn = sys.fn_cdc_get_max_lsn() select [__$start_lsn],[__$operation],[__$update_mask] ,[FirstName],[LastName],[CreditLimit] from cdc.fn_cdc_get_all_changes_CustomerCredit( @begin_lsn, @end_lsn, 'all') __$start_lsn __$operation __$update_mask FirstName LastName CreditLimit ---------------------- ------------ ------------------------------------- ----------------------------------- ----------------------------------- --------------------- 0x00000037000003000004 2 0x3F Chris Skorlinski 1000.00 0x00000037000003290004 4 0x02 Christopher Skorlinski 1000.00 0x00000037000003340004 4 0x10 Christopher Skorlinski 3000.00 0x00000038000000390005 1 0x3F Christopher Skorlinski 3000.00 0x00000038000000B90004 2 0x3F Erica Skorlinski 1000.00 0x00000038000000BA0010 4 0x10 Orlando Gee 2500.00 ... 0x00000038000000EB0040 1 0x3F Robert Lyeba 1000.00 0x00000038000000EB0040 1 0x3F Robert Lyon 1000.00 (123 row(s) affected) /*=================================================== We still see data for DELETED "'Chris','Skorlinski','803-555-1212'"; why? Answer: We're pulling ALL changes for since CDC was enabled, not just recently changed data. How do we only retrive the NEWly change data? Answer: We'll need to start searching all data modified after the first CDC capture. We do this my increasing the MIN LSN (or starting position) to the MAX LSN (ending position) of the previous CDC capture MAX LSN = 0x00000038000000390005 New @begin_lsn = Previous @end_lsn Tip: Use the previous @end_lsn as the "seed" for the fn_cdc_increment_lsn function to find the next "valid" @begin_lsn. ===================================================*/ declare @begin_lsn binary(10), @end_lsn binary(10) set @begin_lsn = sys.fn_cdc_increment_lsn(0x00000038000000390005) --lsn saved 1st run set @end_lsn = sys.fn_cdc_get_max_lsn() select [__$start_lsn],[__$operation],[__$update_mask] ,[FirstName],[CreditLimit] from cdc.fn_cdc_get_all_changes_CustomerCredit( @begin_lsn, @end_lsn, 'all') GO __$start_lsn __$operation __$update_mask FirstName CreditLimit ---------------------- ------------ ------------------------------------- ----------------------------------- --------------------- 0x00000038000000B90004 2 0x3F Erica 1000.00 0x00000038000000BA0010 4 0x10 Orlando 2500.00 ... 0x00000038000000EB0040 1 0x3F Judy 1000.00 0x00000038000000EB0040 1 0x3F Robert 1000.00 0x00000038000000EB0040 1 0x3F Robert 1000.00 (119 row(s) affected) --Show just NET changes since last run declare @begin_lsn binary(10), @end_lsn binary(10) set @begin_lsn = sys.fn_cdc_increment_lsn(0x0000003600000A820005) set @end_lsn = sys.fn_cdc_get_max_lsn() select [__$start_lsn],[__$operation],[__$update_mask] ,[FirstName],[LastName],[Phone],[CreditLimit] from cdc.fn_cdc_get_net_changes_CustomerCredit( @begin_lsn, @end_lsn, 'all') --8 rows were changed twice, only seeing the NET effect. (111 row(s) affected) /*=================================================== What are different techniques to remember the @end_lsn in order to use it as the @begin_lsn on the next run? -- Track the history of processing CDC by capture instance table -- <a href="http://msdn.microsoft.com/en-us/library/bb895315.aspxcreate">http://msdn.microsoft.com/en-us/library/bb895315.aspx</a> create table SalesLT.tblCDCRunHistory_log ( cdc_capture_log_id int identity not null , capture_instance nvarchar(50) not null , begin_time datetime not null , begin_lsn binary(10) not null , end_lsn binary(10) not null , end_time datetime null , status_code int not null default 0 ) =====================================================*/ --Next explore System Tables created by CDC SELECT * FROM cdc.change_tables SELECT * FROM cdc.captured_columns SELECT * FROM cdc.index_columns SELECT * FROM cdc.ddl_history SELECT * FROM cdc.CustomerCredit_CT SELECT * FROM cdc.lsn_time_mapping -- -- To turn off Change Data Capture -- exec sys.sp_cdc_disable_table @source_schema = 'SalesLT' , @source_name = 'CustomerCDCDemo', @capture_instance = 'CustomerCredit' Go Drop Table SalesLT.CustomerCDCDemo go exec sys.sp_cdc_disable_db go |
— Track the history of processing CDC by capture instance table
— <a href="msdn.microsoft.com/…/a>
fn_cdc_get_min_lsn
how can I restrict After Update entry in cdc table.
What are the steps to turn off cdc on a database.Would the below suffice?
exec sys.sp_cdc_disable_db
go