You Can Tune Your Own SQL Code

You Can Tune Your Own Code
SQL Saturday #33 Charlotte

Who Is Mike?
10 years with SQL
DBA roles of various sorts
Blog: www.straightpathsql.com/
Syndicated at SQLServerPedia
Full Time – Principal DBA at global insurance company.
“Spare” Time – Consult for SQL Administration and Performance Issues
President of new “Seacoast SQL” PASS Chapter

Who Are You?

“Why is this so slow?!”
“It worked fine in dev!”
“The results came back fine… I’m done”

What Aren’t We Covering?

“Can’t you
just make it
faster?!”
http://www.flickr.com/photos/irinaslutsky/4000761728/

www.flickr.com/photos/no3rdw/170950846/

http://www.flickr.com/photos/dullhunk/359634390/
www.flickr.com/photos/no3rdw/170950846/

Agenda
Tips For Slow Queries
The Right Mindset & Some Best Practices
Indexes & Statistics (Building Blocks)
Query Plans (Not So Scary)
SQL Profiler (Don’t tell my DBA friends..)
Put it all together and CLAP
DBAs don’t mean to be so mean*
*Maybe we do…, but let’s work it out

Goal 1
You will leave using the concepts we discuss.

Goal 2
You won’t ever say, “done” until you know your code
PERFORMS

Goal 3
“Can’t we all just get along??!”

Tips For Making Queries Slow

Right Mindset

Right Mindset
SQL Is Declarative
Work With Sets
Watch Transaction Footprint
Join Where Necessary
Remember: Disk – Memory – Query
Smaller Sets ASAP
Work with the columns you need

“Should I split this up?”
“Should I use -that- view?”
“How Many Reads Am I doing?”
“What will happen in 1 year?”
“How many rows are affected by that operation?”

How Are You Proving Your Code?
Working with representative volume?
Testing various scenarios?
Before/After Testing?
Using Empirical Evidence?
Look and Feel with a Stop Watch???

Indexes

What Are Indexes?
Pointers To Data
B-Tree Structures
Sometimes – Hero Makers
Sometimes – Frustrations

Clustered Indexes
Leaf Level Is The Data
Narrower Is Better
Ever-Increasing
Order By
Not Changing

Non-Clustered Indexes
Leaf Level Has Index Data and Pointer Only
Joins
Common (and Selective) Search Criteria.

What Does It All Mean?
Scan
Seek
“Bookmark/RID/KEY Lookups”
Covering

Statistics

SARGable Queries

Search ARGuments
Query That Can Use An Index
(All Things Being Equal…)
Generally: =, <, >, <=, =>, BETWEEN, IN, LIKE (with exceptions).
Some Rules but think of the phonebook…

Fun(?) With Phonebooks

Some Tools
IO Statistics
Query Plans
Profiler

Put It Together
Care
Look
Act
Prove It Out

http://www.flickr.com/photos/hikingartist/3515471358/

Goal 3
“Can’t we all just get along??!”

Goal 1
You will leave using the concepts we discuss.

Goal 2
You won’t ever say, “done” until you know your code
PERFORMS

You CAN Tune Your Own SQL Code

Resources
mike@StraightPathSQL.com
www.SQLServerCentral.com
www.SQLServerPedia.com
sqlblog.com
blogs.msdn.com/craigfr/default.aspx
http://sqlinthewild.co.za/
http://scarydba.wordpress.com/
http://www.straightpathsql.com/blogroll/

StraightPathSQL.com/ucandoit

Confused?
Angry?
Lost?

You Can Tune Your Own SQL Code

by mikepwalsh on Jan 31, 2010

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