Table Partitioning in SQL Server

In Sql Server, there are two types of table partitions : Horizontal and vertical. In this article, we will show you, what is Horizontal Table Partitioning in SQL Server and how to create it with example.

SQL Horizontal Table Partition: Dividing table into multiple tables is called Horizontal Table Partition. This is very useful to organise data for quick access. For example, dividing Sales table into Monthly partition, or Quarterly partition will help the end user to select records quickly.

Remember, all the partition tables contains same number of columns.

Before we start create Table Partitioning in SQL Server, let me show you the list of database that are available in our local file system.

From the below screenshot you can see the available databases in our server

For this demonstration we created a new database called PartSample

Now you can see our newly created database PartSample in our file system

Create Table Partitioning in SQL Server

In this example, we will create a table partition to store data in month-wise. I mean, orders or sales in each month will store in separate file group (files with ndf extension).

To achieve the same, we have to create 12 separate file groups for 12 months January to December. To create a file group, we have to use Alter Database command

-- Table Partitioning in SQL Server
ALTER DATABASE PartSample
ADD FILEGROUP January
GO
ALTER DATABASE PartSample
ADD FILEGROUP February
GO
ALTER DATABASE PartSample
ADD FILEGROUP March
GO
ALTER DATABASE PartSample
ADD FILEGROUP April
GO
ALTER DATABASE PartSample
ADD FILEGROUP May
GO
ALTER DATABASE PartSample
ADD FILEGROUP June
GO
ALTER DATABASE PartSample
ADD FILEGROUP July
GO
ALTER DATABASE PartSample
ADD FILEGROUP August
GO
ALTER DATABASE PartSample
ADD FILEGROUP September
GO
ALTER DATABASE PartSample
ADD FILEGROUP October
GO
ALTER DATABASE PartSample
ADD FILEGROUP November
GO
ALTER DATABASE PartSample
ADD FILEGROUP December
GO

OUTPUT

Get FileGroups – Table Partitioning in SQL Server

Use below query to check or see the list of file groups available in this database

-- Table Partitioning in SQL Server
USE PartSample
GO
SELECT * FROM Sys.filegroups

OUTPUT

You can also use below query to return just file group names

-- Table Partitioning in SQL Server
USE PartSample
GO
SELECT name AS [File Group Name] 
FROM Sys.filegroups
WHERE type = 'FG'

OUTPUT

Add ndf files to File Groups – Table Partitioning in Sql Server

Once you created the file groups, you have to add or assign or create ndf files. Below query will add ndf file to January File group

-- Table Partitioning in SQL Server
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartJan],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartJan.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [January]

OUTPUT

Use below query to add ndf files for the remaining 11 month. Remember, this is the physical location where monthly data is going to store.

-- Table Partitioning in SQL Server

-- Adding ndf for February File Group
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartFeb],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartFeb.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [February]

-- Adding ndf for March File Group
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartMarch],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartMarch.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [March]

-- Adding ndf for April File Group
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartApril],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartApril.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [April]

/-- Adding ndf for May File Group
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartMay],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartMay.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [May]

-- Adding ndf for June File Group
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartJune],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartJune.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [June]

-- Adding ndf for July File Group
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartJuly],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartJuly.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [July]

-- Adding ndf for August File Group
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartAug],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartAug.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [August]

-- Adding ndf for September File Group
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartSept],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartSept.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [September]

-- Adding ndf for October File Group
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartOct],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartOct.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [October]

-- Adding ndf for November File Group
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartNov],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartNov.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [November]

-- File Group for December
ALTER DATABASE [PartSample]
    ADD FILE 
    (
    NAME = [PartDec],
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\DATA\PartDec.ndf',
        SIZE = 5080 KB, 
        MAXSIZE = UNLIMITED, 
        FILEGROWTH = 2040 KB
    ) TO FILEGROUP [December]

OUTPUT

Let me open my file system.

From the below screenshot you can see, ndf files has created for each file group

View File groups and respective ndf files – SQL Table partition

Use sys.database_files to get the information about file groups and their physical locations.

-- Table Partitioning in SQL Server
USE PartSample
GO

SELECT * FROM sys.database_files

OUTPUT

You can also use more specific columns in the select statement

-- Table Partitioning in SQL Server
USE PartSample
GO

SELECT name AS [Partition Name],
		physical_name AS [File Path]
FROM sys.database_files 
-- WHERE type_desc = 'ROWS'

OUTPUT

Create Partition Function – Table Partitioning in Sql Server

This function will map the rows from original table (I mean, partition table) to the partition tables. For this, partition function will use one column to identify the file group.

Below function will map original table to file groups based on each month. This function compare the insert date value and map to one of the partition based on the values we specified within the brackets ().

-- Table Partitioning in SQL Server
USE PartSample
GO

CREATE PARTITION FUNCTION [MonthlyPartition] (datetime)
AS RANGE RIGHT FOR VALUES ('20180201', '20180301', '20180401',
               '20180501', '20180601', '20180701', '20180801', 
               '20180901', '20181001', '20181101', '20181201');

OUTPUT

Create Partition Scheme – Table Partitioning in Sql Server

This will map the partition tables with the file groups. Below scheme will map 20180201 to February etc

-- Table Partitioning in SQL Server
USE PartSample
GO

CREATE PARTITION SCHEME MonthWisePartition
AS PARTITION MonthlyPartition
		TO (January, February, March, April, May, June, July, 
			August, September, October, November, December
			);

OUTPUT

Create a Table – Table Partitioning in Sql Server

Let me create a table using the newly created scheme. I suggest you to refer Create table, and Identity Column to understand the below code.

-- Table Partitioning in SQL Server
USE [PartSample]
GO

CREATE TABLE [dbo].[SQL Insert](
	[EmpID] [int] IDENTITY(1,1) NOT NULL,
	[FirstName] [nvarchar](255) NULL,
	[LastName] [nvarchar](255) NULL,
	[Occupation] [nvarchar](255) NULL,
	[YearlyIncome] [float] NULL,
	[Sales] [float] NULL,
	[InsertDate] [datetime] NULL
) ON MonthWisePartition (InsertDate);

OUTPUT

Let me insert few records into the newly created table. Please refer Insert Statement article to understand the insert operations

-- Table Partitioning in SQL Server
USE [PartSample]
GO
 
INSERT INTO [dbo].[SQL Insert] 
VALUES ('Imran', 'Khan', 'Skilled Professional', 15900, 100, GETDATE())
      ,('Doe', 'Lara', 'Management', 15000, 60, GETDATE())
      ,('Ramesh', 'Kumar', 'Professional', 65000, 630, DATEADD(month, 1, GETDATE()))

OUTPUT

You can see those records

Next, we inserted few more records with different dates. Notice, we used DATEADD function to add or delete months from current date.

-- Table Partitioning in SQL Server
USE [PartSample]
GO
 
INSERT INTO [dbo].[SQL Insert] 
VALUES ('Tutorial', 'Gateway', 'Masters', 14500, 200, DATEADD(month, 4, GETDATE()))
      ,('Joe', 'Root', 'Management', 10000, 160, DATEADD(month, 3, GETDATE()))
	  ,('SQL', 'Tutorial', 'Management', 15000, 120, DATEADD(month, 2, GETDATE()))
	  ,('Jhon', 'Wick', 'Software Sales', 21000, 1160, DATEADD(month, -7, GETDATE()))
	  ,('Steve', 'Smith', 'App Sale', 13000, 2160, DATEADD(month, -6, GETDATE()))
	  ,('Kishore', 'Kumar', 'Admin', 120500, 310, DATEADD(month, -5, GETDATE()))
	  ,('Demi', 'Lovato', 'Professional', 193000, 1260, DATEADD(month, -4, GETDATE()))
	  ,('Madison', 'De', 'Management', 90000, 1090, DATEADD(month, -3, GETDATE()))
	  ,('Wang', 'Chung', 'Software Sale', 15000, 1560, DATEADD(month, -2, GETDATE()))
      ,('Dave', 'Jhones', 'Professional', 55000, 630, DATEADD(month, -1, GETDATE()))

OUTPUT

Fro the below screenshot you can see all the records. If you observe the insert dates, each month has one record, and August had 2 records

Table Partitioning in Sql Server – View Records

Use below query to see the total number of rows per file group or partition

-- Table Partitioning in SQL Server
SELECT partition_id AS ID, 
       partition_number AS [Partition Number], 
	   rows AS [Number of Rows]
FROM sys.partitions AS part
WHERE OBJECT_NAME(OBJECT_ID) = 'SQl Insert'

OUTPUT

You can use below query to see the File Group name along with total number of rows.

-- Table Partitioning in SQL Server
USE PartSample
SELECT part.partition_number AS [Partition Number],
		fle.name AS [Partition Name],
		part.rows AS [Number of Rows]
FROM sys.partitions AS part
JOIN SYS.destination_data_spaces AS dest ON
part.partition_number = dest.destination_id
JOIN sys.filegroups AS fle ON
dest.data_space_id = fle.data_space_id
WHERE OBJECT_NAME(OBJECT_ID) = 'SQL Insert'

OUTPUT

TIP: Please refer Create Table Partition article to understand the spruces of creating partition using SQL Management Studio.