1. Partitioning Design
For Performance and Maintainability
Martin Cairns
http://sqlbyparts.com
http://twitter.com/MartinCairnsSQL

2. Who am I?

3. Partitioning Defined
Partitioning (noun)
1. the action or state of dividing or being
divided into parts
2. a structure dividing a space into two parts
Source: http://oxforddictionaries.com/definition/english/partition

4. Types of Partitioning
• Horizontal
• Partition Table by Rows
• Vertical
• Partition Table by Columns
• File Group
• Partition Tables by File Group

5. Horizontal Partitioning
 Divides the rows into small sets by
boundaries
Year PK Order ID Product ID Qty Cost Line XML
2010 1 1 1 5 1.5 <Line…
2010 2 1 1 7 2 <Line…
2011 1000000 20000 345 1000 5 <Line…
2011 1000001 20000 347 3000 12 <Line…
2012 2000000 40000 705 8000 3 <Line…
2012 2000001 40001 706 3000 7 <Line…

6. Vertical Partitioning
 Divides columns from one table into multiple
tables
Year PK Order ID … Year PK Line XML
2010 1 1 … 2010 1 <Line…
2010 2 1 … 2010 2 <Line…
2011 1000000 345 … 2011 1000000 <Line…
2011 1000001 347 … 2011 1000001 <Line…
2012 2000000 705 … 2012 2000000 <Line…
2012 2000001 706 … 2012 2000001 <Line…

7. File Group Partitioning
 File group partitioning is separating the storage of tables
and indexes onto separate database files
 During a Primary File Group restore the whole database
will be offline
 Separate the system & user tables to allow the quickest
restore time
 Since the partitioned database is made up of smaller
parts it is easier to manage the storage location of the
files

8. Using Table Partitioning
 Supports Horizontal Partitioning
 Partition Function defines boundaries based
on a single column
 Partition Scheme defines the File Group
 Inserts automatically supported
 All partitions share the same definition as the
table (indexes, columns, fill factor etc)

9. Table Level Limitations
 Only ~200 steps for each statistics across the
whole table
 Online Index rebuilds are for the whole table
not individual partitions
 Fill Factor
 Lock settings (Row, Page, Escalation, etc)
 Indexes are defined for the whole table rather
than partitions

10. Using View Partitioning
 View Partitioning allows you to overcome
Table Level Constraints
 Check Constraints used to define partitions
 Combine all tables with a UNION ALL View
 Can be used together with Table Partitioning
 Trigger required to allow INSERT with Identity
column
 Allows more complex partitioning schemes

11. Candidates for Partitioning
 Large vs. Small Tables
 Replicated vs. Non-Replicated Tables
 Normal vs. BLOB columns
 Write Heavy Current data vs. Heavily
Read Historic data
 Read Write vs. Read Only Tables

12. Partial Database Availability
 Also referred to as Piecemeal Restore
 Full Recovery Model is Required
 Individual File & File Groups Restore
 Only the Primary File Group is required to
restore a database
 Allows restoring a subset of a correctly
partitioned database for quicker recovery
from a disaster

13. Tipping Point Why is it Table Scanning
 As the number of rows in a table increase the
depth of the B+Tree increases
 The number of Page Reads for a lookup is
equal to the depth of the B+Tree
 The Tipping Point is the point where a Full
Table Scan requires less Page Reads than
the lookups

14. What Does Partition Give Us
 Choices
 Using different Tiers of Storage
 Allows quicker recovery strategies
 Allows partial restores of the database
 Performance
 Allows reduction of overhead of backups
 Allows better query plans due to more
accurate statistics on large tables

15. Demos
 Moving Tables to File Groups
 Partial Restore + Using Partial Restore to
Initialise Replication
 Moving Partition Between Tables For Current
vs. Historic
 Show how View Partitioning can present a
single view of all tables & still support
partition elimination