Karen Lopez @datachick #HeartData

Heart of Data ModelingNormalization…is not your friend…or your Enemy

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@datachick #heartdata

About Kerry

Recovering Sysadmin

Ten years of data—Varying degrees of SQL Server Engine & BI

Currently Senior BIDeveloper/Consultant

Used to fly little airplanes

@airbornegeek

Karen López

Karen has 20+ years of data and information architecture experience on large, multi-project programs.

She is a frequent speaker on data modeling, data-driven methodologies and pattern data models.

She wants you to love your data.

Data Modelers are people, too....so let’s get to know you….

POLL: Who Are You?

What Have You Worked on?

Aug 2014

Attendees, be part of the webinar

Use Q&A for formal questions

Use chat to discuss with each

other

Plan for Today

Why topic?

Why Normalize? Denormalize?

Myths and Truths

10 Tips for Talking About and Doing Normalization

Confession time

I never normalize.

I don’t have the normal forms memorized, nor do I plan to

I believe understanding the principles is important

I believe normalization is NOT a process or a method. More later on that.Not everyone in the data world will agree with me on these things.

NormalizationWhy this Topic?Why NOT this Topic?

Normalization: It’s a Love/Hate Thing.

Normalization, very briefly…

Developed by Ted Codd in the 70s to address update anomalies.

One fact in one place, then referenced instead of duplicated.

One fact means one to create, one item to update, one item to delete.

Normalization, briefly

Normalization…

Is all about the keys, ‘bout the keys, ‘bout the keys…

Depends on understanding the MEANING of the keys and columns

Goes all to heck* when you have surrogate keys

Depends on the make up of the key parts (columns)

Normalization, briefly

1NF – all instances (rows) have the same facts (columns). There are no repeating duplicate columns

2NF – only applies to multi-part keys. No fact is about just part of the key

3NF – No fact depends on another non-key column

3NF

Every fact is either part of a key or depends upon the key, the whole key, and nothing but the key.….so help you Codd

Michael J Swart

Remember…

“Normalization is like marriage…

…you always end up with more relations”

-Data Modeling Essentials, 3rd EditionSimsion & Witt

Enterprise Applications are Complex

20

Myths…

What Normalization is *NOT*

Why People Hate Normalization

Performance

Misunderstood

Taught Wrong Not Sexy

It’s taught wrong? Taught as a process, not a measurement

1NF, 2NF, 3NF, etc.

Used like a grade, instead of measurement

Magical “3NF”

It’s not a process on real projects

1NF 2NF 3NF 4NF BCNF

10 Tips for Data Modelers

1. Stop talking about the normal forms. Just stop.

2. Study the normal forms, know the lingo. Don’t use it, though

3. Be able to explain the anomaly you are trying to avoid.

4. Know your primary and alternate keys.

5. Enforce your primary and alternate keys.

10 Tips for Data Modelers

6. Understand denormalization patterns.

7. Don’t take “needs to be Denormalized” as a change request.

8. Understand other performance tuning techniques and how to recommend them

9. Squash “JOINs are Evil” discussions. They are a feature.

10.Be flexible. That’s why we have architects & modelers.

Thank you, you were great. Let’s do this next month!

Karen Lopez @datachick

#heartdata