Microsoft SQL Server Administration

Partitioning

David Hokszahttp://siret.cz/hoksza

Outline• Partitioned Functions

• Partitioned Schemes

• Partitioned Tables

• Moving Data between Partitions

Partitioning Overview• Partitioning helps to manage large data volumes by

splitting data into smaller parts

o more efficient queries or modification operations (such as archiving)

o filegroups

• reasonable distribution of tables into different files

o vertical partitioning

• column-based table splitting

• less used columns can be moved to another table → manipulating less data (the same goal can be achieved by effective use of SQL querying)

o horizontal partitioning

• row-based table splitting

• partitioned views, partitioned tables and indexes (>2005, enterprise)

Horizontal Partitioning Motivation

• Faster join operation on tables distributed into

partitions based on the same criteria

• Partition-level lock operations (lock escalation)

• Administration operations can be carried out on

some partitions only (archiving, compression, …)

Horizontal Partitioning Overview

1. Build “multi-filegroup” databaseo pre-step

o can be skipped but then the advantage of partitioning decreases

2. Create partition function

3. Create partition schema

4. Create partitioned table

• Partition columno column according to which the data are partitioned

o single column (or computed)

o can have any indexable data type

Create DatabaseCREATE DATABASE test_partition_dbON PRIMARY

(NAME='test_partition_db1',

FILENAME='d:\MSSQLData\MSSQL11.NDBI039\MSSQL\Data\test_partition_db1.mdf',

SIZE = 4,MAXSIZE = 10,FILEGROWTH = 1 ),

FILEGROUP FG2(NAME = ' test_partition_db2',

FILENAME='d:\MSSQLData\MSSQL11.NDBI039\MSSQL\Data\test_partition_db2.mdf',

SIZE = 3,MAXSIZE=100,FILEGROWTH=1 ),

FILEGROUP FG3(NAME = ' test_partition_db3',

FILENAME='d:\MSSQLData\MSSQL11.NDBI039\MSSQL\Data\test_partition_db3.mdf',

SIZE = 3,MAXSIZE=100,FILEGROWTH=1 )

USE test_partition_db

GO

SELECT

name

FROM

sys.filegroups

WHERE

type = 'FG'

SELECT

name, physical_name

FROM

sys.database_files

WHERE

type_desc = 'ROWS'

Partitioning Function• Function specifying how the data are partitioned

CREATE PARTITION FUNCTION

year_partition(DATETIME)AS

RANGE RIGHT

FOR VALUES ('2010-01-01', '2011-01-01')

• RIGHT|LEFTo where the boundary value fallso RIGHT = 2010-01-01 goes to the second partitiono LEFT = 2010-01-01 goes to the first partition

ALTER PARTITION FUNCTION function() {SPLIT RANGE( boundary_value) | MERGE RANGE( boundary_value)}

Partitioning Scheme• mapping partition function onto a physical scheme

CREATE PARTITION SCHEME test_partition_scheme

AS PARTITION year_partition

TO ('PRIMARY', 'FG2', 'FG3')

• for testing purposes instead of TO (…)o ALL TO (PRIMARY)

ALTER PARTITION SCHEME scheme NEXT USED FG

Partitioned Table• Data in a table created on a partition scheme will be

transparently stored in partitions based on the partition function

CREATE TABLE test_partition_table(purchaseDate DATETIME, productNameVARCHAR(50))

ON test_partition_scheme(purchaseDate)

INSERT INTO test_partition_table(purchaseDate, productName)VALUES ('2007-03-25', 'prod1'), ('2009-10-01','prod 2'), ('2010-01-01','prod1'), ('2010-08-09', 'prod3'), ('2010-12-30', 'prod2'), ('2011-01-01', 'prod1'), ('2011-05-24','prod3')

Querying Partitions Metadata

SELECT * FROM sys.partitions

WHERE OBJECT_NAME(object_id)=

'test_partition_table'

SELECT $partition.year_partition('2014-01-

01')

SELECT * FROM test_partition_table

WHERE

$partition.year_partition(purchaseDate) = 2

Partitioning Metadata

credit: SQL Server 2008 Internals

sys.system_internals_allocation_units

sys.partition_range_values

Metadata-based Data Shifting

• metadata-basedo no data shifting, only metadata information is changed

o automatic sliding window technique

• ALTER TABLE → SWITCHo assign a table as a partition to an already existing partitioned table

o switch a partition from one partitioned table to another

o reassign a partition to form a single table

Tasks

1. Create a table for history of played songs in a radio

broadcasting. Partition the table so that each

month will be on a separate partition. Implement a

stored procedure which adds a partition on the

right side automatically (the new boundary will be

based on the data dictionary information) – store

all partitions on PRIMARY FG. Verify the existence of

the new partition.