如何检查 Partiton Scheme是否mark Next Used FileGroup？

检查 Partiton Scheme是否mark Next Used FileGroup，需要使用一个system view：sys.destination_data_spaces，如果存在Next Used FileGroup，那么视图返回的Partition的个数会比Partition Function划分的分区数量+1.

Contains a row for each data space destination of a partition scheme.

表示一个Partition Scheme中的每个Partition和FileGroup之间的关系。

destination_id  是Partition Number

data_space_id  是FileGroupID

1，创建分区函数

-- create parition function
CREATE PARTITION FUNCTION pf_int_Left (int)
AS
RANGE LEFT
FOR VALUES (10,20);

2，创建分区scheme

--create partition scheme
CREATE PARTITION SCHEME PS_int_Left
AS
PARTITION pf_int_Left
TO ([primary], [primary], [primary]);

3，在split partition之前，必须使用alter partition scheme 指定一个Next Used FileGroup。如果Partiton Scheme没有指定 next used filegroup，那么alter partition function split range command 执行失败，不改变partition scheme。

--split range and add new one boudary value
ALTER PARTITION FUNCTION pf_int_Left ()
split range (30);

Msg 7710, Level 16, State 1, Line 2
Warning: The partition scheme ‘PS_int_Left‘ does not have any next used filegroup. Partition scheme has not been changed.

4，如果检查 Partiton Scheme是否指定Next Used FileGroup？

使用sys.destination_data_spaces视图来检查，该系统视图返回Partition 和filegroup之间的Mapping关系。如果一个FileGoup被alter partition scheme 标记为next used Filegroup，那么Partition 的个数会比多Partition function划分的分区多一个。

select ps.name as PartitionSchemeName,
    ps.data_space_id as PartitionSchemeID,
    pf.name as PartitionFunctionName,
    ps.function_id as PartitionFunctionID,
    pf.boundary_value_on_right,
    dds.destination_id as PartitionNumber,
    dds.data_space_id as FileGroupID
from sys.partition_schemes ps
inner join sys.destination_data_spaces dds
    on ps.data_space_id=dds.partition_scheme_id
inner join sys.partition_functions pf
    on ps.function_id=pf.function_id
where ps.name=‘PS_int_Left‘

上述脚本返回3个partition，说明没有next used filegroup。

5，使用 alter partition scheme标记 next used filegroup

--alter partition scheme to mark next used filegroup
ALTER PARTITION SCHEME PS_int_Left
NEXT USED [db_fg1];

查看分区个数

select ps.name as PartitionSchemeName,
    ps.data_space_id as PartitionSchemeID,
    pf.name as PartitionFunctionName,
    ps.function_id as PartitionFunctionID,
    pf.boundary_value_on_right,
    dds.destination_id as PartitionNumber,
    dds.data_space_id as FileGroupID
from sys.partition_schemes ps
inner join sys.destination_data_spaces dds
    on ps.data_space_id=dds.partition_scheme_id
inner join sys.partition_functions pf
    on ps.function_id=pf.function_id
where ps.name=‘PS_int_Left‘

可以看到，多了一个partition，partition number=4，存放的FileGroupID=2。

6，将 FileGroup 取消标记为 next used filegroup

--alter partition scheme to cancel next used filegroup
ALTER PARTITION SCHEME PS_int_Left
NEXT USED;

7,Merge Range移除FileGroup

--merge range
ALTER PARTITION FUNCTION pf_int_Left ()
merge range (20);

查看Partition Function指定的Boundary Value

select pf.name as PartitionFunctionName,
    pf.function_id,
    pf.type,
    pf.type_desc,
    pf.boundary_value_on_right,
    pf.fanout,
    prv.boundary_id,
    prv.value
from sys.partition_functions pf
inner join sys.partition_range_values prv
    on pf.function_id=prv.function_id
where pf.name=‘pf_int_Left‘

绑定到Partition Scheme的Filegroup如下

select ps.name as PartitionSchemeName,
    ps.data_space_id as PartitionSchemeID,
    pf.name as PartitionFunctionName,
    ps.function_id as PartitionFunctionID,
    pf.boundary_value_on_right,
    dds.destination_id as PartitionNumber,
    dds.data_space_id as FileGroupID
from sys.partition_schemes ps
inner join sys.destination_data_spaces dds
    on ps.data_space_id=dds.partition_scheme_id
inner join sys.partition_functions pf
    on ps.function_id=pf.function_id
where ps.name=‘PS_int_Left‘

参考文档：

http://sqlfascination.com/2009/09/30/how-to-remember-the-next-used-filegroup-in-a-partition-scheme/