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At some point in your career you will be asked to get involved in diagnosing performance problems with a database application. Sometimes the diagnosis is simple but in other cases the causes of poor performance are subtle. From my own experience I have noticed that subtle performance bugbears conform to a pattern and I refer to this pattern as “Time Bomb Coding”. The pattern I am referring to has the following properties

• The system is well established
• There has been no significant alterations to the system for some considerable time
• Statistics and indexes are kept up-to-date
• Execution plans appear reasonable at first glance
• The database design appears to be simple and clean
• Traffic has not changed much over time

Despite this the system performance has been steadily degrading!

If this seems familiar to you then you are probably a victim of time bomb coding. In this article I should like to give a few of the many examples of this phenomenon I have come across.

http://www.sqlservercentral.com/articles/Performance+Tuning/69337/

http://arstechnica.com/business/news/2009/12/-the-usb-flash-drive.ars?utm_source=rss&utm_medium=rss&utm_campaign=rss

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Why I prefer surrogate keys instead of natural keys in database design

Simply put:

I prefer using surrogate keys because natural keys are by default a subject to change which is a bad behavior for a row identifier.

But let’s dig a bit deeper into each key type to see why this is. Here’s a little table with column names that tell us what kind of a key each column is.

Surrogate keys

A surrogate key is a row identifier that has no connection to the data attributes in the row but simply makes the whole row unique. And that property is also the downside of it. Because it has no connection to the data attributes we can have two rows with the exact same data in all columns except the key column. This is usually handled at the application side and is an acceptable downside.

An example of a surrogate key is an integer identity or a GIUD unique identifier. I’ve never seen another data type being used as a surrogate key successfully. Both have their pros and cons though.

via Why I prefer surrogate keys instead of natural keys in database design.

Sony’s new “bendable” and transparent organic light emitting diode (OLED) technology is being shown in prototypes featuring an OLED a mere 0.2 mm thick. The prototype devices are a Vaio notebook, a flexible e-book, and a Walkman bracelet.

The OLED screen is transparent and flexible, and the viewing angle range is almost unlimited. OLED technology has a number of advantages over LEDs, including higher efficiency, faster response times, and no requirement for backlighting. The devices also have very low energy needs.

Enlarge

via Super-thin flexible OLED from Sony.

Big Blue says it “absolutely plans to have a significant place in the cloud storage space,” and this is its marker, emblazoned with XIV and BladeCenter.

It dismissively characterises most existing low entry price storage clouds as being been limited to ‘sandbox’ use cases for secondary or tertiary copies of data, or for use in development and test environments. The data is not frequently accessed and doesn’t grow to massive scale. In other words, it is not remotely mission-critical or enterprise grade.

Smart Business Storage Cloud

Its Smart Business Storage Cloud is a private cloud offering, using low-cost components in a scale-out clustered model. The components include XIV storage arrays and BladeCenter servers, plus IBM’s General Parallel File System (GPFS)

There is support for multiple petabytes of capacity, billions of files in a single global namespace and scale-out performance previously limited, Big Blue asserts, to the largest high-performance computing (HPC) systems.

It supports existing file access methods and, IBM says, is highly secure and built to make use of a customer’s “existing security and authentication infrastructure.”

via Big Blue storage cloud is bad news for rivals • The Register.

My colleges asked me if ’squirrely’ is a technical term and for this post the answer is yes. CSS is not going to deny support to customers but SQL Server was not tested in this scenario so you may have chased yourself up a tree, hence I use the term squirrely.

SQL Server 2005 introduced snapshot databases and modified DBCC to create secondary snapshot streams for online DBCC operations. The online DBCC creates a secondary stream of the database files that is SPARSE. CSS has found that if a 3rd party backups and utilities or NT Backup is used against the database files the SPARSE setting may get incorrectly, propagated to the parent stream. In the case of DBCC this is the original database files(s).

Repro

via CSS SQL Server Engineers : Did your backup program/utility leave your SQL Server running in an squirrely scenario?.