Archive for November, 2008

Comment by Duke Ganote on Foreign Keys in a Data Mart

Exactly. When code values in the facts aren’t in the master dimensional data, I create similar NTB (“needs to balance” :) dimensional records.

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Comment by LewisC on Foreign Keys in a Data Mart

When you say gaps, do you mean instances where you might have late arriving dimensional data or dirty data that needs to be cleaned prior to loading? In those cases, I usually use “data not arrived yet” and “dirty record” FKs. I set up a surrogate key like -1, -2 whatever. When the data finally comes in and is cleaned, I update the fact to the correct key value.

I have also used an all encompassing -1 depending on requirements. That one is a “might be null, missing or data”.

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Comment by Duke Ganote on Foreign Keys in a Data Mart

I’m curious how you deal with gaps in referential integrity: our ETL team coined the phrase “shoring up the dimensions” when referring to the dummy records I require to be built. (BTW, since the dummy records are ETL-created, I didn’t have any issues with ETL-enforced integrity — until I found not everyone was “rabid about referential integrity”).

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Comment by LewisC on Mini-Tip #9: No Data Found: Bug or Feature?

Ah. Thanks for the link. I’m glad that it is at least documented. Still seems like a bug to me, though.

Thanks,

LewisC

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Comment by Duke Ganote on Mini-Tip #9: No Data Found: Bug or Feature?

I suppose I better try to commit this (mis)behavior to memory, since it just bit me again today. The 10gR2 documentation includes this about NO_DATA_FOUND “Because this exception is used internally by some SQL functions to signal completion, you should not rely on this exception being propagated if you raise it within a function that is called as part of a query.”

http://tinyurl.com/5o7ze3

My exception clause now looks like:

EXCEPTION

WHEN NO_DATA_FOUND THEN

RAISE

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VMWare Enters the Cloud

VMWare is the virtualization king and I have been wondering when they would chose to enter the cloud competition. Until now, it’s pretty much been Amazon’s game to win or lose. According to this article, VMWare is opening a data center in Washington state. The new data center will be 189,000 square feet, of which [...]

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High Performance MySQL Book Review

I have added my previously posted mysql book review to the site under “Reference Information” -> “Book Review”.
LewisC
Technorati : book review, mysql

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Additions to Reference Section

I just added new topics under the reference information link. I added documentation, downloads and book reviews.
LewisC
Technorati : book reviews, documentation, downloads, rerference

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Comment by LewisC on Foreign Keys in a Data Mart

Duke,

That is pretty much where I am.

In this instance, the ETL is being handed off to others who will write the code (hand written, they decided not to use an ETL tool). There is no real documentation as of yet and there is a short time line for delivery.

To me, not enforcing FKs is a recipe for disaster.

Thanks for the input.

LewisC

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Comment by Duke Ganote on Foreign Keys in a Data Mart

Lewis–

In my opinion:

1) every datamart should have FK, at least in RELY DISABLE NOVALIDATE state for documentation and optimization purposes.

2) As for validation… well, I’ve been experiencing a half-revolution in my thinking on this (a full revolution would be 360 degree and you’d just end up where you started).

In my prior experiences, I designed the marts and the ETL. So I knew it was done right (IMHO :) , and I relied on ETL validations in this 3-step fashion:

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Comment by LewisC on Foreign Keys in a Data Mart

sschurig,

Interesting viewpoint. Thanks for sharing it. That’s the kind of info I was looking for.

I agree with at least putting them in and not enforcing. That would be at a minimum, for me.

I do disagree with some of your points, though. I believe the db should be the final say of RI. I actually use RI when doing ETL to make the ETL less complicated. Why put it in code when it can go into the database?

I have seen and worked with a huge number of data

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The Computers of Tomorrow

Is Cloud Computing a new idea? As a matter of a fact, it is not. Is comparing cloud computing to the electric utilities a new concept. As a matter of a fact, it is not. What does this sound like:
ANALOGY WITH ELECTRICITY The computing machine is fundamentally an extremely useful device. The service it provides [...]

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SQL DML Ebook Available, Free Online

LewisC’s An Expert’s Guide to Oracle Technology
Ok, I figured out how I am going to do this. I am making my book available three ways: print, ebook and html.
For print, you can get it on amazon or through my e-store. It’s $14.95
For ebook, you can g…

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Google App Engine Gets Perl, Sort Of

If you are not familiar with it, Google App Engine is Google’s entry in the cloud, specifically a PaaS or Platform as a Service. With the Google App Engine, you get an IDE (python) to code your applications and then you deploy it to the Google cloud. You can integrate with other google services (as [...]

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Foreign Keys in a Data Mart

LewisC’s An Expert’s Guide to Oracle Technology
I am soliciting opinions here. First, though, some back story.
Way back when, when I was first moving on the track to data modeler and architect, I was responsible for designing schemas and application…

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Voices in the Clouds

One of the big difficulties of the cloud is properly defining it. I don’t think it will be completely defined for a while yet. Since that is the case, I think I would like to muddy the waters a little more.
Is VOIP a cloud service? It’s a service, runs on the internet, on someone else’s [...]

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Major New Section – SQL Starter

I just added chapter 1 from my new book, The SQL Starter Book 1 – DML.  The link to the web based content is here.  I will add the rest of the chapters over time.

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SQL Newbie Book

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SQL Newbie Book

I have written a new book on SQL DML. This is a total beginner book: how to commit and rollback, how to query, how to add data, etc.

Probably not of interest to most of the people who read this blog but if you know of anyone completely new to SQL, this would make a great Christmas present. Only 14.95. It is completely vendor agnostic, although the examples all use Oracle and MySQL.

You can view the Table Of Contents, Preface and Index here. I plan to release some of the chapters for free on the blog and will make the PDF of the book available at a discount. I have several more books like this (DDL, Intro to Relational Databases and Cloud Computing) under construction. I also plan to do some intermediate and advanced books in the future.

LewisC

Technorati : database, learning, mysql, sql

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Cloud Computing Defined

LewisC’s An Expert’s Guide to Oracle Technology
I’ve finally done it. Everyone seems to be having difficulties defining just exactly what cloud computing really is. I have it down to a single sentence:
Cloud computing is using the internet to access…

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Learn SQL – The Guide to DML

LewisC’s An Expert’s Guide to Oracle Technology
My SQL book is now available for print. You can see it on my CreateSpace e-store. The book is SQL DML – SQL Starter Series Book 1. This is a book for beginners. It takes someone step by step through TC…

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Oracle Book Survey From Packt – Get 40% Off EBooks

Packt is a publishing company. I will be reviewing one of their books here in the near future. They are doing a survey and anyone who responds can get 40% off any ebook in their inventory. I just wanted to pass this along. The survey is only 9 quest…

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First Ebook Coming Soon

Well, I pretty much have the first book written. It is a SQL newbies guide called SQL Starter – DML. In it, I give the details about DML. I plan to follow on with two more in the starter series, Intro to Relational Databases and SQL Starter – DDL.
I…

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AVG and ZoneAlarm Are Giving it Away!

LewisC’s An Expert’s Guide to Oracle Technology
AVG
Last week, AVG suggested to some users that user32.dll was a trojan and offered to delete the file for them. Know what happens when you delete a key dll like that? Kerblooey, that’s what.
AVG has s…

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Favorite Interface to Amazon AWS?

LewisC’s An Expert’s Guide to Oracle Technology
I am familiar with several different interfaces to AWS. The three I am most familiar with and have used are Elastic fox, Cloud Studio and amazon’s command line interface. I’ve also heard of a paid GUI …

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Top 10 Tips For a DBA

LewisC’s An Expert’s Guide To Oracle Technology
So you want to be a DBA? A DBA’s day is busy and difficult. Like a wizard’s, only you don’t get to hang around with dragons and elves. For those of you thinking about becoming a DBA, here is a list of …

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Oracle EBooks

LewisC’s An Expert’s Guide to Oracle Technology
I’ve decided that my next writing task (besides the blog here), will be a series of ebooks. I am thinking that I will start with Intro To SQL, Intro to Relational Databases, Modern Replication Tools, R…

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Data Breach: Express Scripts Pharmacy

LewisC’s An Expert’s Guide To Oracle Technology
Once more unto the breach, dear freinds, once more.
Express Scripts Warns of Potential Large Data Breach Tied to Threat
I used Express Scripts on at least one prior job so this kind of sucks for me as …

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