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Webcast Recording Available: Why Be Normal? CA ERwin Modeling User Group

Dec 8, 2010   //   by Karen Lopez   //   Blog, Data, Data Modeling, Database, Social Networking, Speaking  //  No Comments

As I blogged last week, I participated in a webcast on social networking for data management professionals.  That webcast was recorded and is now available for viewing.}3%22PW4Q

Handouts of the slides I presented on the cost, benefits and risks of social networking are also available.

Handouts for OEMUG / CA Global Modeling User Group Why Be Normal Webcast

If you are reading my blog and on any of these social networks, I’d love to friend/follow/link to you. My contact information for those services are in the handouts. If you do send me a request, please mention that you are a blog reader, attended an event I presented at, or where we met.

Presentation Handouts for SQLSaturday NYC and DC

Dec 7, 2010   //   by Karen Lopez   //   Blog, Data, Data Modeling, Database, Speaking  //  1 Comment

I’ve uploaded handouts for my Database Design Contentious Issues presentations for SQLSat59 (New York City) and SQLSat61 (Washington, DC).

Both audiences were Contentious, which is just perfect for this presentation.

Handouts Database Design Contentious Issues – New York 2010

Handouts Database Design Contentious Issues – DC 2010

As a reminder, if you attended these sessions, please take a moment and leave a testimonial/ration at  It helps me and event planners.  Please help us participate in more of these events.

I’m a Rockstar Blogger…Bloggess…Blogmistress…Bloggette?

Dec 6, 2010   //   by Karen Lopez   //   Blog, Social Networking  //  2 Comments


I was excited to see that I’ve been recognized as a Rockstar Blogger by Thomas LaRock (blog | @SQLRockstar) at the tempdb level (entry level).  Tempdb is a SQL Server system database and all of Tom’s rockstar bloggers are awarded a level based on these system databases.

As a TempDB level blogger, I fit this profile:

The tempdb group has the bloggers that I want to recognize for doing good work. However, they are also the group of bloggers that could most easily fall off and never been seen again, just like a temp table. There is no line separating names in this group, because they are all equally eligible for promotion or relegation back into my general RSS feeds.

Read more:

It is a great honour to be listed with all the bloggers on Tom’s list.  You should check out Tom’s blog, plus the others he has listed.  I recommend all of them as well.

Happy Reading.

Identity Column Issues and Trade-offs

Dec 1, 2010   //   by Karen Lopez   //   Blog, Data, Data Modeling, Database, DLBlog  //  4 Comments

This post is based on a post I previously blogged on 30 May 2008…but like most design approaches, it still holds true.

If you’ve heard me present, then you know that one of my primary design mantras is:

Everything is a trade off.  You need to be able to explain, in both business and technical terms, the cost, benefits, and risks associated with every design decision.

If you can’t do that, then you aren’t doing design: you are copying design patterns from other designs and hoping for the best outcome, even if your current design has different requirements and risk tolerances.

I am often told that a database design must have surrogate keys on every table and that “right” way to implement surrogate keys is to use the Identity property in SQL Server (or the RowID in Oracle, or the Identity property in DB2).  These sorts of features of modern DBMSs do vary from vendor to vendor, so the cost, benefit, and risk associated with each varies by version and by vendor.  Most IT pros I speak with don’t realize that.

Many people I speak with assume, incorrectly, that Identity Property = Surrogate Key = Primary Key= Unique Index but this is not true. It is important for database designers to understand the differences between these concepts.

Nigel Rivett has written a great article over at about SQL Server’s identity property and some of the interesting “features” of this incrementing function:

Note: An identity column is not guaranteed to be unique nor consecutive. You should always place a unique index on an identity column if your system requires uniqueness.

Note: The next value is the step added to the current seed; not one more than the max value in the table, or even the step from the last or maximum value.

I’m guessing that 6+ out of 10 of experienced SQL Server designers and developers are not clear on these two gotchas.  Other DBMSs have technical issues as well.  When I’m questioned on why I don’t just slap on an identity property, call it a PK an move on to the next change request, I usually start asking questions:

  • Will the application need to assume that the values are always sequential?  What if the sequence is missing a few steps?  Will that break the code?
  • Will the Identity column value be displayed anywhere outside the database, such as on a report or on a screen?
  • Will the users be confused if a sequence is missing or if they “restart” in the middle of an order?
  • Will the Identity column value be used outside this database? How?  Where?
  • What are our plans for dealing with rows that exceed the maximum number of identity values (in some versions of DB2, identity values maxed out at 32k or so)?

Identity properties can be useful, but as in every design decision, there are uses that are appropriate and uses that are not — it all comes down to cost, benefit, and risk.

Twitter: How Has It Made You Better at Your Job?

Nov 29, 2010   //   by Karen Lopez   //   Blog, Social Networking  //  4 Comments

One of the issues I struggle with in getting people to understand why I tweet is demonstrating the value of engaging with others to people who haven’t engaged on Twitter.  Yes, it’s a Catch-22

I have read that the majority of the people who sign up for Twitter (and other social networks) create an account, post something like “I have an account”, the sit back and wait for all the magic to come their way.  But these networks don’t work that way.  The benefits I’ve realized  don’t happen because I broadcast a message but because I’ve had very brief conversations with smart people like you from all over the world. 

Yes, I do tend to post some personal items like the pictures of odd or funny things I’ve seen in my day, but for the most part I’m on Twitter, Facebook, and LinkedIn for professional reasons.  Sure, I appreciate the parking space that Noel and Tamara donated to me, the collection of postal packages that Yanni and John provided and a nice spot to sleep this week at Erin’s place, but those came because I had already engaged with these people prior to asking for help.

Located between snippets of fun are my DB2, SQL Server, WordPress and a myriad of other technical questions and answers I received from the Twitterverse.  Sometimes from existing contacts and sometimes from strangers.

Before the network of networks I could have done my best to interpret vague documentation, called the tool vendor, called one person who I think worked with these technologies, or found a forum and posted my question.  I still do those, but 9 times out of 10 an answer comes back from a social network long before these other resources had time to respond.

My ability to reach out to ask if anyone is using feature X of product Z, to ask for opinions of the best way to accomplish Y or if anyone knows the best place to get a dead car fixed(Chicago, 2010) has helped my clients and me respond faster, with better answers than ever before.

What have you told not-yet-ready-for-prime-time people about why they should be blogging, Tweeting, posting to Facebook, etc. for their professional lives?  What would be the best way to demonstrate the resources available to them?

Contest: Tell Me Why You Need a New Tassimo Brewing System

Nov 29, 2010   //   by Karen Lopez   //   Blog, Social Networking  //  9 Comments

Good news:  Tassimo Canada sent me a new home brewing system to try.

Great news: Tassimo Canada has given me TWO more Tassimo Brewing Systems to give away to blog readers. 

Tassimo Brew Bot – *not* Exactly as shown

This contest is open only to Canadian residents.  Sorry everyone else.  I hope you have been good this year; maybe you can ask Santa for one.  We do have future contests planned, so stand by.  But over there.  Yeah, a little bit further over.  Thanks.

To make this easy, the management team at InfoAdvisors will be choosing the two best answers to this question:

How would having instant access to an infinite number of fresh cups of coffee make you more productive at work?

The rules:

  1. Must be a Canadian resident to comment and win.
  2. Comments are moderated an subject to our posting guidelines.
  3. One comment per person.
  4. You must give your answer in the comments to this blog post.  Comments posted elsewhere will be read and enjoyed but not considered.
  5. A winner will be chosen from answers posted prior to 6PM EST 30 Nov.  That’s tomorrow!
  6. You have to supply a valid e-mail address in your comment so that we can contact you with instructions on how to claim your prize.
  7. A skills testing question will need to be answered.
  8. Two systems will be awarded, one each to two people.
  9. All selections are final.  No cash equivalents.  No substitutions. Your mileage may vary.  Subject to arcane laws in your local jurisdiction.  Do not immerse this rule in water.

I am Speaking: OEMUG – Cleveland 1 Dec 2010

Nov 26, 2010   //   by Karen Lopez   //   Blog, Data Modeling, Database, Social Networking, Speaking  //  1 Comment

On Wednesday, 1 December 2010 I’ll be speaking three times at the Ohio Enterprise Modeling User Group:

10 AM ET

Classic Data Modeling Mistakes & How to Avoid Them

We’ve all been there: a shortcut here, a compromise there, an over-modeling over there. In this presentation, Karen demonstrates classic and all-too-common data modeling mistakes that are easy to make and yet just as easy to avoid. We’ll look at data modeling generalizations, applying surrogate keys, understanding the difference between design and business requirements, data model changes, flags, and sharing data models.

11 AM ET

Modeling Global User Community Webcast: Normalization of Social Networking in the ERwin Community

In this webcast, panelists discuss social networking from an ERwin data professional perspective. Facebook, InfoAdvisors, LinkedIn, Twitter, My CA,, and data-centric tool social networks offer many options for you to join a virtual data community. If you are new to social networking, a seasoned tweeter, or just want to use social networking more efficiently, this webcast is ideal for you.

  • Social Networking 101
  • Deeper Dive / Benefits for Data Professionals
  • Security / Personal and Professional Boundaries
  • “Why Be Normal?”


Data Modeling Contentious Issues

A highly interactive session for seasoned modelers, attendees evaluate the options and best practices of common and advanced data modeling issues, such as:

  • Party/party role
  • Natural vs. surrogate keys
  • Varchar Minimums
  • Identity Crisis
  • SOAs, Ontologies, ESBs, New TLAs and Shoe Strings
  • What is Logical? What is Physical? Why Do We Care?
  • Politics vs. Customer Satisfaction

Participants in this session will be presented with an issue along with a range of responses or possible solutions. We will vote on preferred response, then the group as a whole will discuss the results, along with the merits of each possible response. The goal of this workshop is to help practitioners identify potential points of conflict in data modeling, as well as alternative approaches to resolving the issues.

During the event there is a presentation by Donna Burbank about upcoming release of ERwin v8.

I hope to see you there.

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