Advanced Index Tuning for SQL Server

Advanced Index Tuning

Brent Ozar
SQL Server MVPfor Quest Software
SQLServerPedia Ed.
SQL, SAN, VM admin
Dot-com-crash experience
Performance freak
Twitter @BrentO
Blog: www.BrentOzar.com
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Today’s Agenda
Passive Tuning
Active Tuning
Index Compression
The Silent Killer
Resources and Q&A

Passive Tuning with DMVs

DMV Tuning Lifecycle

Removing Indexes

Results

Why Are Writes Different?

Our Table: Items

Indexes On An “Item” Table
Index #1:
UPC_Code
Index #2:
SupplierID
Index #3:
Category
QtyInStock
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Data In The Index

But When It Changes…

That’s Why…

Our Query

A Better Way: Includes
CREATE INDEX
IX_Category_Includes
ON dbo.Items (Category)
INCLUDE (QtyInStock)

And When It Changes…

Query Plan

Remember, Never SELECT *

Leave a Bread Crumb Trail

Missing Index Query

Okay – Now What?

When Do We Add Indexes?

Active Tuning: The Wizards

Danger! Danger!

The End Result
CREATE NONCLUSTERED INDEX [_dta_index_Activity_11_1977058079__K1_K4_K7_K5_K3] ON [dbo].[Activity]
(
[ServerName] ASC,
[ActivityTypeID] ASC,
[StatusTypeID] ASC,
[StartTime] ASC,
[DatabaseID] ASC
)

Rename Each Index
CREATE NONCLUSTERED INDEX [IX_ServerName_ActivityTypeID_StatusTypeID_StartTime_DatabaseID] ON [dbo].[Activity]
(
[ServerName] ASC,
[ActivityTypeID] ASC,
[StatusTypeID] ASC,
[StartTime] ASC,
[DatabaseID] ASC
) ON [PRIMARY]

Makes Ongoing Tuning Easier

Active Tuning Summary
Don’t just click apply
Use smart names
Look for overlaps
Go passive first

SQL 2008 Data Compression

Estimating Compression
sp_estimate_data_compression_savings
@schema_name
@object_name
@index_id
@partition_number
@data_compression

Index Compression Drawbacks
Enterprise Edition only
No inheritance
No automation

The Silent Performance Killer

Pretend You’re SQL Server
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13% to 460%Faster

Absolutely No:
App changes
Vendor issues
Testing required
Guessing on indexes
Backfires

Not All Unicorns and Roses
Standard Edition: Offline Only
Enterprise Edition: Most Online
Generates a lot of transaction logs

The Native Solution

The Better Way: T-SQL Code