dyl*_*anT 6 sql-server change-tracking sql-server-2014
我在一个大约有 300 万行的表上打开了 SQL Server 更改跟踪。
开启变更追踪:
ALTER DATABASE FooDB
SET CHANGE_TRACKING = ON
(CHANGE_RETENTION = 10 DAYS, AUTO_CLEANUP = OFF)
ALTER TABLE [dbo].[fooTable]
ENABLE CHANGE_TRACKING
WITH (TRACK_COLUMNS_UPDATED = OFF)
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如果我单独编辑行,一切都很好,每个插入/更新/删除都会存储一个更改。
如果我运行更新多行的更新查询,我只会在更新中获得第二行的更改记录。
所以:
UPDATE fooTable SET name = UPPER(name) where id between 100 and 200
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其次是(以确保对每一行进行实际更新)
UPDATE fooTable SET name = LOWER(name) where id between 100 and 200
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仅生成记录 101 的更改记录。
SQL Express 2014
我已经弄清楚发生了什么事。
我做出的错误假设是,如果更改导致同时更新 4 行,则会导致表的 SYS_CHANGE_VERSION 增加 4。但事实并非如此。尽管changetable中有四次更改,但版本仅上升1(这是一次更改更改了多条记录。)
任何有兴趣亲自测试它的人都可以使用下面的代码。
-- 1. Create Table
CREATE TABLE dbo.fooTable(
[ID] [int] IDENTITY(1,1) NOT FOR REPLICATION NOT NULL,
[Title] [nvarchar](20) NULL,
[Surname] [nvarchar](128) NULL,
[MiddleNames] [nvarchar](128) NULL,
[Firstname] [nvarchar](128) NULL,
[CreateDate] [datetime2](7) NOT NULL CONSTRAINT [DF_CustomerProfile_CreateDate_I] DEFAULT (getdate()),
[LastModifiedDate] [datetime2](7) NOT NULL CONSTRAINT [DF_CustomerProfile_LastModifiedDate_I] DEFAULT (getdate()),
CONSTRAINT [PK_fooTable_I] PRIMARY KEY CLUSTERED
(
[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON)
)
GO
-- 2. Insert dummy data
insert into fooTable (Title, Firstname, MiddleNames, Surname, CreateDate, lastModifiedDate)
values ('Mr','John',null,'Smith',GetDate()-5, getdate())
insert into fooTable (Title, Firstname, MiddleNames, Surname, CreateDate, lastModifiedDate)
values ('Mrs','Mary','Beth','Jones',GetDate()-5, getdate())
insert into fooTable (Title, Firstname, MiddleNames, Surname, CreateDate, lastModifiedDate)
values ('Ms','Thanh',null,'Nguyen',GetDate()-5, getdate())
insert into fooTable (Title, Firstname, MiddleNames, Surname, CreateDate, lastModifiedDate)
values ('Dr','Lee','Evan','Oscars',GetDate()-5, getdate())
-- 3. Turn on Change Tracking
-- Database
ALTER DATABASE fooDB
SET CHANGE_TRACKING = ON
(CHANGE_RETENTION = 10 DAYS, AUTO_CLEANUP = OFF)
-- Tables
ALTER TABLE dbo.fooTable
ENABLE CHANGE_TRACKING
WITH (TRACK_COLUMNS_UPDATED = OFF)
-- 4. Check current version
Select CHANGE_TRACKING_CURRENT_VERSION() -- Should be Zero if you have never turned change tracking on before.
-- 5. Make a single change
Update fooTable set MiddleNames = 'Arthur' where Surname = 'Smith'
-- 6. Check current version, should have gone up by 1
Select CHANGE_TRACKING_CURRENT_VERSION() -- Should be 1 if you have never turned change tracking on before.
-- 7. See the change, should be Type U on record with ID 1
DECLARE @version bigint
SET @version = CHANGE_TRACKING_CURRENT_VERSION()-1
Select CT.*
FROM CHANGETABLE(CHANGES dbo.fooTable, @version) CT
-- 8. If everything is OK up to here, that's great. Now we have a problem.
-- Update all the rows in the table
Update fooTable set lastModifiedDate = Getdate() + 5
-- 9. Check current version, I expected it would go up by 4, one update for each record
Select CHANGE_TRACKING_CURRENT_VERSION() -- Should be 5 if you have never turned change tracking on before.
-- 10. View all changes for the table. There should be 4 (the first one will be gone now.)
Select CT.*
FROM CHANGETABLE(CHANGES dbo.fooTable, 0) CT
-- Observe that each row has the same SYS_CHANGE_VERSION which means I need to deal with it and move on.
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