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In This Issue
A Note from the Editor
Developer Perspectives
Snapshot Isolation vs. NoLock
eLibrary Short Takes
Cut to the Cache: Shortcut to ASP.NET 2.0 Performance
Achieve Compliance and Manage Threats Simultaneously
Tech Talk
Glad You Asked: Interested in a Programming Career? Here's How to Start
For 'um Developers
Letters to the Editor
Info to Go
New and Improved
Localize Your Software in 3 Steps
Enter Frequently Used Text in a Flash
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A Note From the Editor
You might notice that this newsletter looks a bit different. As Bill Sheldon
described in his columns "Will .NET Survive" (http://www.sqlmag.com/Article/ArticleID/49049/sql_server_49049.html)
and "A Ripple Becomes a Wave" (http://www.sqlmag.com/Article/ArticleID/49304/sql_server_49304.html),
Developer .NET UPDATE is sporting a new name--Developer Update--and some new
features. One notable new feature is the "Glad You Asked" column in which
Bill will answer readers' questions. In addition to these changes, the
newsletter will be published once a month (the first Friday of each month)
instead of twice a month. This new schedule will start with the August 4 issue.
Developer Perspectives
by Bill Sheldon, bills@interknowlogy.com
Snapshot Isolation vs. NoLock
One of my least favorite features of Microsoft SQL Server is that it lets
you apply a NoLock hint within a query. The NoLock hint tells SQL Server
that, for the current query, you'd like to read the data from a given table
while ignoring any locks. In systems in which there are multiple processes
trying to simultaneously access the same resource, NoLock is advantageous
because it allows user queries to operate without needing to wait for updates
to finish. The disadvantage is that in many cases users read data that hasn't
been committed to the database or is only partially in place, which can
produce unexpected results.
I usually find the NoLock hint in use by Web applications that are well
behaved but the business tier has a custom-reporting capability, import
capability, or both. For example, a common pattern is that in order to speed
custom reporting, the system occasionally reads from five or six related
tables, then inserts or updates all the data used to create reports into a
single table. Rather than update the reporting table as changes occur on the
source table, the developers thought they could speed the system by batching
these updates. Similarly, for data import, there's one giant statement that
takes a table or a file of data from another system and attempts to insert
all the rows in a single SQL statement.
The problem with batching updates and using giant statements is that SQL
Server holds locks until the entire transaction completes. As a result,
users' queries against the involved tables are suspended, making it seem like
the application has frozen. The easy solution is to add the NoLock hint,
which allows these queries to occur while these massive updates statements
run their course.
At this point, a quick review seems in order. When you're creating a
transaction, you want to follow the Atomicity, Consistency, Isolation, and
Durability (ACID) principle. Atomicity doesn't refer to an atom bomb but
rather that a transaction should be processed completely or not at all. Thus,
you should work with the smallest possible unit. For example, it's better to
process one order and its accompanying set of order details rather than
10,000 orders and all of their accompanying details.
Granted, NoLock usually lets organizations survive with few noticeable
errors. However, I had been looking forward to SQL Server 2005 because it was
supposed to provide an alternative to using NoLock. In SQL Server 2005,
Microsoft introduced Snapshot Isolation. The basic idea is that transactions
are held in suspense; thus, a long-running transaction (e.g., 10,000 orders)
wouldn't hold locks during the transaction's update cycle, allowing reads to
be done against clean data.
Unfortunately, Snapshot Isolation has two problems that keep it from being
a good replacement for NoLock. The first problem is that enabling the
Snapshot Isolation option in a database requires an additional 14 bytes of
space per row in every table. Given that most companies that have broken the
transaction rules have also created some very wide tables, this space
requirement can be a problem.
The second and bigger problem is how this feature is implemented.
Specifically, when data is written to a database, SQL Server 2005 writes all
the data to a temporary table in TempDB instead of updating the actual
database. When the transaction completes, SQL Server 2005 moves the data from
TempDB storage to the database. This means that the system will likely need
additional hardware to provide more I/O capacity.
Unfortunately, I suspect that the majority of organizations that could
really benefit from Snapshot Isolation won't be willing to pay the price to
implement it. Of course, the real solution is to not have long-running
transactions, but then everyone agrees with that in principle. For more
information about Snapshot Isolation in SQL Server 2005, I suggest that you
go to http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnsql90/html/sql2k5snapshotisol.asp.
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eLibrary Short Takes
Cut to the Cache: Shortcut to ASP.NET 2.0 Performance
Whether you're an ASP .NET developer who works with data-based
applications or a SQL Server DBA supporting ASP.NET applications, you'll find
new capabilities in ASP.NET 2.0 to help you boost your Web site's
performance. With the release of SQL Server 2005, Visual Studio 2005, and
Microsoft .NET Framework 2.0, Microsoft continues to enhance its support at
every tier of an ASP.NET application. Learn about the performance-boosting
features that ASP.NET 2.0 introduces in "ASP.NET 2.0: Cache In on Performance
Shortcuts " in the July issue of SQL Server Magazine.
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Tech Talk
Glad You Asked
by Bill Sheldon, bills@interknowlogy.com
Interested in a Programming Career? Here's How to Start
Q: I read your "Back to Basics" article in Developer Update
(http://www.sqlmag.com/articles/index.cfm?articleid=49610&).
I've previously worked as a network/telecom/hardware/software support manager,
but I'd now like to start a career in programming. I know almost nothing about
programming except for some classes I took years ago. Can you suggest a
starting point for me?
A: Programming is more or less a generic task done by several different
groups of IT professionals. So, I think the starting point for you is to look
at some of the broad IT categories and see which one best fits your goals and
expectations. The idea is to concentrate on an area in which you can be
successful. So, let's look at four primary categories of IT professionals and
what their skill sets are:
Database administrator (DBA). DBAs work with database systems, such as
Microsoft SQL Server. They can focus on two areas: systems administration and
programming. In the systems administration area, the tasks include setting up
accounts and permissions for database users as well as monitoring a database's
runtime performance. However, good DBAs go beyond just running a report. They
optimize data access. For example, they evaluate stored procedures' execution
plans, optimize stored procedures' code, and optimize databases' indexes. Good
DBAs are proficient in the skills covered by the Microsoft Certified DBA
(MCDBA) certification.
Traditional IT professional. The traditional IT professional is more of a
system engineer. In large organizations, IT professionals might specialize in
the setup and maintenance of a single server product (e.g., Windows Server
2003, Microsoft Exchange Server), whereas in small organizations, IT
professionals might need to work with half a dozen or more server products. A
talented IT professional not only knows how to open a user-management console
to add a new user but also understands how to optimize products through
administrative programming and other tools. Although the IT professionals'
primary focus isn't programming, having some programming experience helps them
be successful. These types of professionals become proficient in the skills
covered in the Microsoft Certified Systems Engineer (MCSE) or Microsoft
Certified Systems Administrator (MCSA) certification.
Information worker. Microsoft is promoting a new category of IT
professionals known as information workers. At my company, information workers
are specialists at customizing applications and client desktops. They typically
customize products in the Microsoft Office suite. In Office 2007 that includes
client applications such as Excel and server applications such as Office
SharePoint Server. There are many certifications associated with information
workers, so I'm not going to list them all but they include the Microsoft
Office Specialist (MOS), Microsoft Certified Technology Specialist (MCTS), and
Microsoft Certified Desktop Support Technician (MCDST). For more information
about some of the training available to information workers, I suggest going to
http://www.microsoft.com/learning/mls/elearn/iw.mspx.
Software developer. Software development is the traditional focus of
programming. However, talented software developers do more than just write
code. They also solve customer problems and design and document systems. In my
opinion, a good software developer needs about 5 years of experience to be able
to work independently. These developers are proficient in the skills covered by
the Microsoft Certified Solution Developer (MCSD) and Microsoft Certified
Application Developer (MCAD) certifications.
Taking into consideration these four categories of IT professionals, you
should determine the type of development you want to pursue in your career. A
good place to review the skill sets in all of the Microsoft certifications is
at http://www.microsoft.com/learning/mcp/default.mspx.
For 'um Developers
Forum participant Gazzoid is performing full text searches in databases.
He wants to whether it's possible to retrieve the name of the columns that
the results were found in. If you can help Gazzoid, go to
http://sqlforums.windowsitpro.com/web/forum/messageview.aspx?catid=66&threadid=48148&enterthread=y
Letters to the Editor
What's on your mind? Let us know at kbemowski@windowsitpro.com.
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New and Improved
Send information about your developer-related products to products@sqlmag.com
Localize Your Software in 3 Steps
Sisulizer Ltd. has released Sisulizer, a Windows application that lets
software developers localize their applications into multiple languages.
Localization is a three-step process. First, you scan the application and
locate all the text. Sisulizer works with Visual C++, Visual Basic (VB),
Windows binary files, .NET assemblies, and more. Second, you translate the
text with Sisulizer's visual editor. Third, you build the localized version.
Sisulizer handles all languages, including right-to-left and double-byte
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Enter Frequently Used Text in a Flash
Softvoile announced the release of Flashpaste 3.6, a customizable tool to
enter frequently used text. It's easy to use. You just enter the frequently
used text, then specify the cover string that will represent this text in the
Flashpaste popup list. Then, anytime you need to enter your predefined text,
you press a hot key to bring up the Flashpaste popup list and select the
cover string from that list. You can also use Flashpaste to create macros.
Flashpaste Professional costs $19.95. The company also offers Flashpaste
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Contact Us
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