如何更改现有分区的 FILEGROUP (SQL Server)

问题描述

我有一个非常大的表，我按月进行了分区。我还为每年创建了文件组，因此每个文件组最多可容纳当年的 12 个分区。这是分区函数：

CREATE PARTITION FUNCTION [PF_MonthlyPartition](datetime) 
AS RANGE RIGHT FOR VALUES (N'2019-06-01T00:00:00.000',N'2019-07-01T00:00:00.000',N'2019-08-01T00:00:00.000',N'2019-09-01T00:00:00.000',N'2019-10-01T00:00:00.000',N'2019-11-01T00:00:00.000',N'2019-12-01T00:00:00.000',N'2020-01-01T00:00:00.000',N'2020-02-01T00:00:00.000',N'2020-03-01T00:00:00.000',N'2020-04-01T00:00:00.000',N'2020-05-01T00:00:00.000',N'2020-06-01T00:00:00.000',N'2020-07-01T00:00:00.000',N'2020-08-01T00:00:00.000',N'2020-09-01T00:00:00.000',N'2020-10-01T00:00:00.000',N'2020-11-01T00:00:00.000',N'2020-12-01T00:00:00.000',N'2021-01-01T00:00:00.000',N'2021-02-01T00:00:00.000')

问题是，我的最后一个分区不是在 FG_2021 中，而是在 PRIMARY 文件组中。

Data Distribution right now

如何将该分区的文件组更改为 FG_2021？

我当前的分区方案最终看起来像这样：

CREATE PARTITION SCHEME [PS_MonthWise] AS PARTITION [PF_MonthlyPartition] 
TO ([FG_2019],[FG_2019],[FG_2020],[PRIMARY],[FG_2021])

解决方法

在将数据移动到正确的 FG 时，您是否有能力让错误的分区不可用/为空？如果是这样，将分区切换到一个空表，发出必要的 create index... with (drop_existing = on...) on [FG_2021] 命令来物理移动数据，更改分区函数以合并“坏”分区，再次更改分区函数以重新添加分区边界（这次使用正确的 FG），然后将分区（从步骤 1）切换回主表。错误的分区看起来没有那么大，所以这应该很快。

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更新

这是一个虚拟数据库中的快速重现：

/*setup*/
use master;
drop database if exists prtTest;
create database prtTest;
alter database prtTest add FILEGROUP [FG_2019];
alter database prtTest add file (
    name = 'FG_2019',filename = 'c:\temp\FG_2019.ndf',size = 10mb) 
to filegroup [FG_2019];

alter database prtTest add FILEGROUP [FG_2020];
alter database prtTest add file (
    name = 'FG_2020',filename = 'c:\temp\FG_2020.ndf',size = 10mb
) to filegroup [FG_2020];

alter database prtTest add FILEGROUP [FG_2021];
alter database prtTest add file (
    name = 'FG_2021',filename = 'c:\temp\FG_2021.ndf',size = 10mb
) to filegroup [FG_2021];

use prtTest;
go
CREATE PARTITION FUNCTION [PF_MonthlyPartition](datetime) 
AS RANGE RIGHT FOR VALUES (N'2019-06-01T00:00:00.000',N'2019-07-01T00:00:00.000',N'2019-08-01T00:00:00.000',N'2019-09-01T00:00:00.000',N'2019-10-01T00:00:00.000',N'2019-11-01T00:00:00.000',N'2019-12-01T00:00:00.000',N'2020-01-01T00:00:00.000',N'2020-02-01T00:00:00.000',N'2020-03-01T00:00:00.000',N'2020-04-01T00:00:00.000',N'2020-05-01T00:00:00.000',N'2020-06-01T00:00:00.000',N'2020-07-01T00:00:00.000',N'2020-08-01T00:00:00.000',N'2020-09-01T00:00:00.000',N'2020-10-01T00:00:00.000',N'2020-11-01T00:00:00.000',N'2020-12-01T00:00:00.000',N'2021-01-01T00:00:00.000',N'2021-02-01T00:00:00.000');
CREATE PARTITION SCHEME [PS_MonthWise] AS PARTITION [PF_MonthlyPartition] 
TO ([FG_2019],[FG_2019],[FG_2020],[PRIMARY],[FG_2021]
);

create table dbo.foo (dt datetime) on [PS_MonthWise](dt);
create clustered index [IX_foo] on dbo.foo(dt) on [PS_MonthWise](dt);

insert into dbo.foo (dt)
values 
    ('2021-01-01'),('2021-01-02'),('2021-02-01'),('2021-02-02');
select *,$partition.[PF_MonthlyPartition](dt)
from dbo.foo;

/*end setup*/

/*run this query after any partition function changes*/
select p.partition_number,prv.[value],fg.name,p.[rows]
from sys.partitions as p
left join sys.allocation_units as au
    on au.container_id = p.hobt_id
    and au.[type] in (1,3)
left join sys.filegroups as fg
    on fg.data_space_id = au.data_space_id
left join sys.partition_range_values as prv
    on prv.boundary_id = p.partition_number
where object_id = object_id('dbo.foo')
order by partition_number;

create table dbo.temp_foo (dt datetime) on [PRIMARY];
create clustered index [IX_foo] on dbo.temp_foo(dt) on [PRIMARY];

alter table dbo.foo switch partition 21
    to dbo.temp_foo;

create clustered index [IX_foo] on dbo.temp_foo(dt) 
    with (drop_existing = on) on [PS_MonthWise](dt);

alter partition function [PF_MonthlyPartition]()
    merge range (N'2021-01-01T00:00:00.000');

alter partition scheme [PS_MonthWise]
    next used [FG_2021];

alter partition function [PF_MonthlyPartition]()
    split range (N'2021-01-01T00:00:00.000');

alter table dbo.temp_foo switch partition 21
    to dbo.foo partition 21;