[英]Merging 2 tables that were partitioned together via “UNION ALL”
我想在当前数据库中找到一个常见的模式。 我有3个对象,其中一个就足够了: current_table
, history_table
, combined_view
。
current_table
和history_table
具有完全相同的列,并包含在时间戳上拆分的数据,即history_table
包含截至2010-01-01的数据, current_table
包含此后的数据,包括2010-01-01等。
合并的视图是(穷人的分区)
select * from history_table
UNION ALL
select * from current_table
我想有一个与视图同名的表,并与history_table
和视图一起使用。 我的算法是:
我目前通过以下SQL实现上述(2):
INSERT INTO current_table
SELECT * FROM history_table
我想(2)是花费大部分时间的地方。 我担心上面的插入将尝试为插入的每一行写一个日志,并且会比可能慢。 在这种情况下,移动数据的最佳方法是什么? 我不在乎记录这些动作。
这将批量
select 1
while (@@rowcount > 0)
begin
INSERT INTO current_table ct
SELECT top (100000) * FROM history_table ht
where not exists ( select 1 from current_table ctt
where ctt.PK = ht.PK
)
end
我根本不会移动数据,特别是如果您要重复此练习。 使用一些分区技巧来随机整理元数据。
1)根据您的分居日期创建一个具有两个分区的中间登台表。 2)创建最终的目标表,以您的视图命名,没有分区。 3)将数据从现有表切换到分区表。 4)将两个分区合为一个分区。 5)将剩余的分区切换到新的目标表中。 6)放下所有工作物体。 7)根据需要重复。
-- Step 0.
-- Standard issue pre-cleaning.
IF OBJECT_ID('dbo.OldData','U') IS NOT NULL
DROP TABLE dbo.OldData;
IF OBJECT_ID('dbo.NewData','U') IS NOT NULL
DROP TABLE dbo.NewData;
IF OBJECT_ID('dbo.CleanUp','U') IS NOT NULL
DROP TABLE dbo.CleanUp;
IF OBJECT_ID('dbo.AllData','U') IS NOT NULL
DROP TABLE dbo.AllData;
IF EXISTS (SELECT * FROM sys.partition_schemes
WHERE name = 'psCleanUp')
DROP PARTITION SCHEME psCleanUp;
IF EXISTS (SELECT * FROM sys.partition_functions
WHERE name = 'pfCleanUp')
DROP PARTITION FUNCTION pfCleanUp;
-- Mock up your existing situation. Two data tables.
CREATE TABLE dbo.OldData
(
[Dates] DATE NOT NULL
,[OtherStuff] VARCHAR(1) NULL
);
CREATE TABLE dbo.NewData
(
[Dates] DATE NOT NULL
,[OtherStuff] VARCHAR(1) NULL
);
INSERT INTO dbo.OldData
(
Dates
,OtherStuff
)
VALUES
(
'20090101' -- Dates - date
,'' -- OtherStuff - varchar(1)
);
INSERT INTO dbo.NewData
(
Dates
,OtherStuff
)
VALUES
(
'20110101' -- Dates - date
,'' -- OtherStuff - varchar(1)
)
-- Step .5
-- Here's where the solution starts.
-- Add check contraints to your existing tables.
-- The partition switch will require this to be sure
-- the incoming data works with the partition scheme.
ALTER TABLE dbo.OldData
ADD CONSTRAINT ckOld CHECK (Dates < '2010-01-01');
ALTER TABLE dbo.NewData
ADD CONSTRAINT ckNew CHECK (Dates >= '2010-01-01');
-- Step 1.
-- Create your partitioning artifacts and
-- intermediate table.
CREATE PARTITION FUNCTION pfCleanUp (DATE)
AS RANGE RIGHT FOR VALUES ('2010-01-01');
CREATE PARTITION SCHEME psCleanUp
AS PARTITION pfCleanUp
ALL TO ([PRIMARY]);
CREATE TABLE dbo.CleanUp
(
[Dates] DATE NOT NULL
,[OtherStuff] VARCHAR(1) NULL
) ON psCleanUp(Dates);
-- Step 2.
-- Create your new target table.
CREATE TABLE dbo.AllData
(
[Dates] DATE NOT NULL
,[OtherStuff] VARCHAR(1) NULL
);
-- Step 3.
-- Start flopping metadata around.
ALTER TABLE dbo.OldData
SWITCH TO dbo.CleanUp PARTITION 1;
ALTER TABLE dbo.NewData
SWITCH TO dbo.CleanUp PARTITION 2;
-- Step 4.
-- Your old tables should be empty now.
-- Put all of the data into one partition.
ALTER PARTITION FUNCTION pfCleanUp()
MERGE RANGE ('2010-01-01');
-- Step 5.
-- Switch that partition out to your
-- spanky new table.
ALTER TABLE dbo.CleanUp
SWITCH PARTITION 1 TO dbo.AllData;
-- Verify the data's where it belongs.
SELECT *
FROM dbo.AllData;
-- Verify the data's not where it shouldn't be.
SELECT * FROM dbo.OldData;
SELECT * FROM dbo.NewData;
SELECT * FROM dbo.CleanUp ;
-- Step 6.
-- Clean up after yourself.
DROP TABLE dbo.OldData;
DROP TABLE dbo.NewData;
DROP TABLE dbo.CleanUp;
DROP PARTITION SCHEME psCleanUp;
DROP PARTITION FUNCTION pfCleanUp;
-- This one's just here for me.
DROP TABLE dbo.AllData;
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