SQL SERVER – 2005 – Database Table Partitioning

Partitioning is the database process or method where very large tables and indexes are divided in multiple smaller and manageable parts. SQL Server 2005 allows to partition tables using defined ranges and also provides management features and tools to keep partition tables in optimal performance.

Tables are partition based on column which will be used for partitioning and the ranges associated to each partition. Example of this column will be incremental identity column, which can be partitioned in different ranges. Different ranges can be on different partitions, different partition can be on different filegroups, and different partition can be on different hard drive disk to improve performance.

Partitions can be set up very easily using schemes and functions as well can manage very easily humongous tables separate indexes for each partition. This will lead to high performance gain. Partitioning can increase performance when hard disk speed is performance bottleneck, if CPU or RAM is bottleneck partitioning will not help much.

How to horizontal partition database table

Step 1 : Create New Test Database with two different filegroups

Example  using C: Drive, however to take advantage of partition it is recommended that different file groups are created on separate hard disk to get maximum performance advantage of partitioning. Before running following script, make sure C: drive contains two folders – Primary and Secondary as following example has used those two folder to store different filegroups.

USE Master;

GO
--- Step 1 : Create New Test Database with two different filegroups.
IF EXISTS (
SELECT name
FROM sys.databases
WHERE name = N'TestDB')
DROP DATABASE TestDB;
GO
CREATE DATABASE TestDB
ON PRIMARY
(NAME='TestDB_Part1',
FILENAME=
'C:\Data\Primary\TestDB_Part1.mdf',
SIZE=2,
MAXSIZE=100,
FILEGROWTH=1 ),
FILEGROUP TestDB_Part2
(NAME = 'TestDB_Part2',
FILENAME =
'C:\Data\Secondary\TestDB_Part2.ndf',
SIZE = 2,
MAXSIZE=100,
FILEGROWTH=1 );
GO
















































































































Step 2 : Create Partition Range Function

Partition Function defines the range of values to be stored on different partition. For our example let us assume that first 10 records are stored in one filegroup and rest are stored in different filegroup. Following function will create partition function with range specified.

USE TestDB;

GO
--- Step 2 : Create Partition Range Function
CREATE PARTITION FUNCTION TestDB_PartitionRange (INT)
AS RANGE LEFT FOR
VALUES (10);
GO










Step 3 : Attach Partition Scheme to FileGroups
Partition function has to be attached with filegroups to be used in table partitioning. In following example partition is created on primary and secondary filegroup.

USE TestDB;

GO
--- Step 3 : Attach Partition Scheme to FileGroups
CREATE PARTITION SCHEME TestDB_PartitionScheme
AS PARTITION TestDB_PartitionRange
TO ([PRIMARY], TestDB_Part2);
GO




Step 4 : Create Table with Partition Key and Partition Scheme
The table which is to be partitioned has to be created specifying column name to be used with partition scheme to partition tables in different filegroups. Following example demonstrates ID column as the Partition Key.

USE TestDB;

GO
--- Step 4 : Create Table with Partition Key and Partition Scheme
CREATE TABLE TestTable
(ID INT NOT NULL,
Date DATETIME)
ON TestDB_PartitionScheme (ID);
GO




Step 5 : (Optional/Recommended) Create Index on Partitioned Table
This step is optional but highly recommended. Following example demonstrates the creation of table aligned index. Here index is created using same Partition Scheme and Partition Key as Partitioned Table.

USE TestDB;

GO
--- Step 5 : (Optional/Recommended) Create Index on Partitioned Table
CREATE UNIQUE CLUSTERED INDEX IX_TestTable
ON TestTable(ID)
ON TestDB_PartitionScheme (ID);
GO




Step 6 : Insert Data in Partitioned Table
Insert data in the partition table. Here we are inserting total of 3 records. We have decided that in table partition 1 Partition Key ID will contain records from 1 to 10 and partition 2 will contain reset of the records. In following example record with ID equals to 1 will be inserted in partition 1 and rest will be inserted in partition 2.

USE TestDB;

GO
--- Step 6 : Insert Data in Partitioned Table
INSERT INTO TestTable (ID, Date) -- Inserted in Partition 1
VALUES (1,GETDATE());
INSERT INTO TestTable (ID, Date) -- Inserted in Partition 2
VALUES (11,GETDATE());
INSERT INTO TestTable (ID, Date) -- Inserted in Partition 2
VALUES (12,GETDATE());
GO




Step 7 : Test Data from TestTable
Query TestTable and see the values inserted in TestTable.

USE TestDB;

GO
--- Step 7 : Test Data from TestTable
SELECT *
FROM TestTable;
GO




Step 8 : Verify Rows Inserted in Partitions
We can query sys.partitions view and verify that TestTable contains two partitions and as per Step 6 one record is inserted in partition 1 and two records are inserted in partition 2.

USE TestDB;

GO
--- Step 8 : Verify Rows Inserted in Partitions
SELECT *
FROM sys.partitions
WHERE OBJECT_NAME(OBJECT_ID)='TestTable';
GO




















































Partitioning table is very simple and very efficient when used with different filegroups in different tables. I will write very soon more articles about Table Partitioning. If you need any help in table partitioning or have any doubt, please contact me and I will do my best to help you.




About Author:
Nirmal Doshi is budding technology geek, who helps Systems Plus with his creativity and research on technology. He works in systems Plus and actively contributes to technology. He can be contacted at: nirmal.d@spluspl.com