CREATE PARTITION SCHEME (Transact-SQL)

Članek
03/27/2023

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance

Creates a scheme in the current database that maps the partitions of a partitioned table or index to one or more filegroups. The values that map the rows of a table or index into partitions are specified in a partition function. A partition function must first be created in a CREATE PARTITION FUNCTION statement before creating a partition scheme.

Note

In Azure SQL Database only primary filegroups are supported. Learn more about filegroups and partitioning strategies in Filegroups.

Transact-SQL syntax conventions

Syntax

CREATE PARTITION SCHEME partition_scheme_name  
AS PARTITION partition_function_name  
[ ALL ] TO ( { file_group_name | [ PRIMARY ] } [ ,...n ] )  
[ ; ]

Arguments

partition_scheme_name
Is the name of the partition scheme. Partition scheme names must be unique within the database and comply with the rules for identifiers.

partition_function_name
Is the name of the partition function using the partition scheme. Partitions created by the partition function are mapped to the filegroups specified in the partition scheme. partition_function_name must already exist in the database. A single partition cannot contain both FILESTREAM and non-FILESTREAM filegroups.

ALL
Specifies that all partitions map to the filegroup provided in file_group_name, or to the primary filegroup if [PRIMARY] is specified. If ALL is specified, only one file_group_name can be specified.

file_group_name | [ PRIMARY ] [ ,...n]
Specifies the names of the filegroups to hold the partitions specified by partition_function_name. file_group_name must already exist in the database.

If [PRIMARY] is specified, the partition is stored on the primary filegroup. If ALL is specified, only one file_group_name can be specified. Partitions are assigned to filegroups,starting with partition 1, in the order in which the filegroups are listed in [ ,...n]. The same file_group_name can be specified more than one time in [ ,...n]. If n is not sufficient to hold the number of partitions specified in partition_function_name, CREATEPARTITION SCHEME fails with an error.

If partition_function_name generates fewer partitions than filegroups, the first unassigned filegroup is marked NEXT USED, and an information message displays naming the NEXT USED filegroup. If ALL is specified, the sole file_group_name maintains its NEXT USED property for thispartition_function_name. The NEXT USED filegroup will receive an additional partition if one is created in an ALTER PARTITION FUNCTION statement. To create additional unassigned filegroups to hold new partitions, use ALTER PARTITION SCHEME.

When you specify the primary filegroup in file_group_name [ ,...n], PRIMARY must be delimited, as in [PRIMARY], because it is a keyword.

Only PRIMARY is supported for SQL Database. See example below.

Permissions

The following permissions can be used to execute CREATE PARTITION SCHEME:

ALTER ANY DATASPACE permission. This permission defaults to members of the sysadmin fixed server role and the db_owner and db_ddladmin fixed database roles.
CONTROL or ALTER permission on the database in which the partition scheme is being created.
CONTROL SERVER or ALTER ANY DATABASE permission on the server of the database in which the partition scheme is being created.

Examples

A. Creating a partition scheme that maps each partition to a different filegroup

The following example creates a partition function to partition a table or index into four partitions. A partition scheme is then created that specifies the filegroups to hold each one of the four partitions. This example assumes the filegroups already exist in the database.

CREATE PARTITION FUNCTION myRangePF1 (INT)  
AS RANGE LEFT FOR VALUES (1, 100, 1000);  
GO  
CREATE PARTITION SCHEME myRangePS1  
AS PARTITION myRangePF1  
TO (test1fg, test2fg, test3fg, test4fg);

The partitions of a table that uses partition function myRangePF1 on partitioning column col1 would be assigned as shown in the following table.

Filegroup	Partition	Values
`test1fg`	1	col1 <= `1`
`test2fg`	2	col1 > `1` AND col1 <= `100`
`test3fg`	3	col1 > `100` AND col1 <= `1000`
`test4fg`	4	col1 > `1000`

B. Creating a partition scheme that maps multiple partitions to the same filegroup

If all the partitions map to the same filegroup, use the ALL keyword. But if multiple, but not all, partitions are mapped to the same filegroup, the filegroup name must be repeated, as shown in the following example.

CREATE PARTITION FUNCTION myRangePF2 (INT)  
AS RANGE LEFT FOR VALUES (1, 100, 1000);  
GO  
CREATE PARTITION SCHEME myRangePS2  
AS PARTITION myRangePF2  
TO ( test1fg, test1fg, test1fg, test2fg );

The partitions of a table that uses partition function myRangePF2 on partitioning column col1 would be assigned as shown in the following table.

Filegroup	Partition	Values
`test1fg`	1	col1 <= `1`
`test1fg`	2	col1 > `1` AND col1 <= `100`
`test1fg`	3	col1 > `100` AND col1 <= `1000`
`test2fg`	4	col1 > `1000`

C. Creating a partition scheme that maps all partitions to the same filegroup

The following example creates the same partition function as in the previous examples, and a partition scheme is created that maps all partitions to the same filegroup.

CREATE PARTITION FUNCTION myRangePF3 (INT)  
AS RANGE LEFT FOR VALUES (1, 100, 1000);  
GO  
CREATE PARTITION SCHEME myRangePS3  
AS PARTITION myRangePF3  
ALL TO ( test1fg );

D. Creating a partition scheme that specifies a 'NEXT USED' filegroup

The following example creates the same partition function as in the previous examples, and a partition scheme is created that lists more filegroups than there are partitions created by the associated partition function.

CREATE PARTITION FUNCTION myRangePF4 (INT)  
AS RANGE LEFT FOR VALUES (1, 100, 1000);  
GO  
CREATE PARTITION SCHEME myRangePS4  
AS PARTITION myRangePF4  
TO (test1fg, test2fg, test3fg, test4fg, test5fg)

Executing the statement returns the following message.

Partition scheme 'myRangePS4' has been created successfully. 'test5fg' is marked as the next used filegroup in partition scheme 'myRangePS4'.

If partition function myRangePF4 is changed to add a partition, filegroup test5fg receives the newly created partition.

E. Creating a partition scheme only on PRIMARY

In Azure SQL Database, adding files and file groups is not supported, but table partitioning is supported by partitioning across only the PRIMARY filegroup.

The following example creates a partition function to partition a table or index into four partitions. A partition scheme is then created that specifies that all partitions are created in the PRIMARY filegroup.

CREATE PARTITION FUNCTION myRangePF1 (INT)  
AS RANGE LEFT FOR VALUES (1, 100, 1000);  
GO  
CREATE PARTITION SCHEME myRangePS1  
AS PARTITION myRangePF1  
ALL TO ( [PRIMARY] );

Next steps

Learn more about table partitioning and related concepts in the following articles:

Deli z drugimi prek