• Client/Server Performance, Part 1: Blocking

  June 16, 2010 Michael Sansoterra

  It is no secret that read performance can generally be improved by the age-old “blocking” mechanism whereby many rows are fetched at once in preparation for a program to process them. So how is blocking done in the client/server world? Assuming that the good old IBM i will be the server, the following code samples (C#, Java, VBA, and DRDA) show an example of how to increase the amount of data that can be transferred from the server to the client. C# Using ADO.NET and the IBM DB2 UDB for iSeries .NET Provider For applications that need to buffer large

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• SQL Performance: IN vs. EXISTS

  June 16, 2010 Hey, Ted

  Concerning your article Update One File Based on Another File, I would agree that the IN is more intuitive than the EXISTS. When looking at the volume of data, possible number of rows to update, and the rows returned for the IN, is there a preferred method if considering performance? Does the IN or EXISTS result in better performance under certain conditions? –Sarah The prevailing wisdom is that EXISTS currently tends to outperform IN. Here are comments from two readers that support that position. A nice consequence of going the IN route (as opposed to using EXISTS) is that,

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• How Do I Tell These Partitions Apart?

  June 16, 2010 Hey, Joe

  My organization has five different i/OS partitions. Yesterday, I thought I was working on a test partition green screen and it turned out that I was signed on to a production system. Worse, I deleted a production file and it caused a lot of problems. Can you think of any good way I can stop that from happening in the future? –Jim One of the few problems with i/OS is that there isn’t any “are you sure?” button that pops up when you’re going to delete a file. And in one of the few areas that I think Windows has

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• Re-Adopt Authority Utility

  June 9, 2010 Patrick Botz

  Adopted authority is a great way to avoid giving users direct access to data. However, there are a couple of challenges with changing an existing application to rely on adopted authority. First, adopted authority is not propagated to submitted jobs. Second, adopted authority must be removed whenever a command line is provided for the end user. Third, in a production environment it is difficult to find which programs must adopt authority without breaking production users. Alternative public authority, as described in my previous tip, addresses the last issue. This tip addresses the first issue. To describe the tip, I’ll

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• Date Field Odds and Ends

  June 9, 2010 Hey, Competent Professional

  Thirty years ago we stored dates and times in alphanumeric and numeric fields, because we didn’t have date, time, and timestamp data types. Many shops still store dates in alpha and numeric fields, some of them because they still run applications that date back to those dates, others because they’ve never bothered to learn to use the new data types. Here are three tips for working with date fields. I hope you enjoy them. Feel free to add to the discussion. Hey, Ted: In the old days, when dates were stored in numeric or alpha fields, we used invalid date

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• Admin Alert: How To Run NetServer from the Green Screen in 10 Minutes

  June 9, 2010 Joe Hertvik

  IBM i NetServer is a handy server. With very little configuration, it allows i/OS machines to provide file and print-sharing services for Windows-based PC clients. Unfortunately, NetServer has an image problem. Many people think they can only control NetServer through iSeries Navigator and that there isn’t a green-screen interface for NetServer. They are wrong. There are green-screen NetServer commands, and you may already have them installed on your machine. Here’s a quick overview of what i5/OS NetServer is, and how you can start, stop, configure, and control it through 5250 green-screen commands. What is IBM i NetServer? Originally called iSeries

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• Five Steps To Monitoring Your Server Log on IBM i

  May 26, 2010 Pi Guang Ming

  In today’s Web application environment, notices and error messages that appear in a Web server’s logging files can be easily lost or missed. This exposes you to missing important information that you may need to know. The Web Log Monitor gives users the capability to monitor the contents of log files for any Web-related server, including the Integrated Web Application Server, Integrated Web Services Server, WebSphere Application Server, WebSphere Portal Server, and IBM‘s HTTP Server. Users can set rules for the Web Log Monitor. If a situation matches the rule parameters, the monitor sends a notification to: The *QSYSOPR

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• Distinctly Speeding Up DISTINCT

  May 26, 2010 Ted Holt

  The DISTINCT keyword is a great example of the power of the SQL SELECT statement. Add this powerful word to any SELECT command and voilà! Duplicate rows magically disappear. Comments from readers have alerted me to the fact that some people find use of this feature confusing. Here are a brief discussion of DISTINCT and a performance tip. Given a table (physical file) of sales order information and a table of customer information, how do I go about finding the account numbers of customers who have orders in the database? We could try this: select s.companyno, s.customerno from salesordh as

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• Hey! What Happened To My Last Used Dates

  May 26, 2010 Hey, Joe

  After we upgraded our production system to new Power i hardware, the Last used date on all our system objects was reset to zeros. While this isn’t a major problem, it does mean that we are no longer able to identify obsolete objects and files on our system. If we can’t identify them, then we can’t remove them. Is there any way to get this information back? –Bert Thanks, Bert. Unfortunately, if you migrated your existing production partition to a new system and restored all the objects to that system, all your objects’ Last used dates are gone. Here’s how

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• Low Risk Authority Changes

  May 19, 2010 Patrick Botz

  For years, many people, including me, have harangued you to “get rid of PUBLIC” authority. Despite all of the pleading, however, there remains a large number of customers that still have PUBLIC authority set to *USE or higher. I suspect at least part of the reason is because many of us are afraid to monkey with PUBLIC authority for fear of breaking something major. This fear is understandable. Many administrators are responsible for applications that were written before they joined the workforce. A fairly trivial technique that I call “alternative PUBLIC authority” takes the fear–and the risk–out of changing PUBLIC

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