• Guru: Physical System Performance

  November 15, 2021 Dawn May

  Almost all IBM i shops use logical partitioning and have several partitions on a single Powerbox. There may be several IBM i partitions, VIOS partitions, and possibly AIX or Linux on Power partitions. Regardless of what type of operating system is running in the partition, the hypervisor collects performance metrics for all partitions. These performance metrics are always being collected, and you can allow a partition access to these performance metrics. In the case of IBM i, this physical system performance data can be gathered by Collection Services. IBM documents this feature in Collecting and displaying CPU utilization for all …

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• Guru: Abstract Data Types and RPG

  November 8, 2021 Ted Holt

  An abstract data type (ADT) is a type of data and a set of operations defined over that type of data. Using ADTs allows a programmer to work with data in terms of functionality rather than physical representation. The ADT is the basis of object-oriented programming. Does that mean that abstract data types don’t apply to procedural languages like RPG? Not at all. Quite the contrary.

  Before I show you how you can use abstract data types in RPG-based applications, let me further illustrate abstract data types with another, non-OO object — the user profile. The user profile is a …

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• Guru: Flexible Interfaces

  November 1, 2021 Ted Holt

  The details are murky, it’s been eons ago. Probably the mid-1990’s. I was working on an AS/400 that ran a mixture of System/36 and native applications. I needed to call a program that had been written in the latest version of RPG from both S/36 RPG II and native RPG III (a.k.a. RPG/400) programs. I hope I’m remembering this correctly. It’s been so long.

  The problem I ran into was rooted in a numeric parameter. S/36 programs passed numeric parameters in zoned decimal format, whereas native RPG and CL programs used packed decimal. The called program defined the parameter as …

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• Guru: Quick And Handy RPG Output, Take 2

  October 25, 2021 Ted Holt

  I am pleased today to revisit a topic I wrote about just over seven and a half years ago. I do so for two reasons. First, I’ve made a slight improvement to my routine. Second, I’d like to provide more examples of this routine in action. My previous article suffered from a paucity of examples. I can’t believe I let that happen.

  I’m talking about the writeln subprocedure, a handy routine that I use to write unstructured text to a spooled file. I derived the inspiration for this routine from Pascal, a programming language I used heavily when I was …

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• Guru: What Is Constant Folding And Why Should I Care About It?

  October 18, 2021 Ted Holt

  Constant folding is a compiler-optimization technique, whereby the compiler replaces calculations that involve constants with the result values when possible. Constant folding is common in modern compilers, and according to the RPG reference, the RPG compiler uses this technique. (See the documentation of the %div and %rem functions, for example.)

  But you and I don’t write compilers. We write business applications. Why then should we care about constant folding? That’s a question worth pondering.

  Consider how I used to have to write RPG in the Dark Ages.

  C                     MOVE CUSTNR    CUSTSV  50
  

  Here I’m copying the customer account number to …

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• Guru: Fall Brings New RPG Features (And So Did Spring!)

  October 4, 2021 Jon Paris

  When I first sat down to write this tip my focus was on introducing you to the new RPG features that were added alongside the latest September Technology Refresh (TR). However, when I tried to reference one of the enhancements from the spring enhancements, I quickly discovered that I had never written those up for the Guru column!

  Oooopppps! As a result, this “tip” will cover all the RPG enhancements added this year, both in the April and September announcements. It will be in two parts. This first part will cover the array-oriented features.

  RPG’s range of array-processing options has …

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• Guru: Alternate SQL Row-Selection Criteria Revisited Revisited

  September 27, 2021 Ted Holt

  I am not a “do as I say and not as I do” kind of person. After I wrote the article Guru: Alternate SQL Row-Selection Criteria Revisited, I got serious about using dynamic SQL in my RPG programs instead of enabling and disabling logical expressions in the WHERE clause. I’m reliving the days when OPNQRYF was my best friend, trying to make apostrophes play nice with string concatenation.

  Overall, I’m happy with the change. When I have converted the switch-laden version to dynamic SQL, I have seen a noticeable performance improvement in some cases, and at least a slight …

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• Guru: RDi 9.6, Part 11 – New Features for Experienced RDi Users

  September 20, 2021 Susan Gantner

  Just when you thought my multi-part series on V9.6 of RDi was surely finished, it’s back! It seems like the song that never ends. Happily, though, since more new features have been added to RDi, many of which are the direct result of RFEs (a.k.a. Requests for Enhancement) from RDi users like you and me.

  We’ve waited longer than usual for release 9.6.0.11, but it’s available now. I’ll cover the enhancements in this release in a couple of tips. This first tip will target mostly experienced RDi users. The next one will focus on some of the enhancements to ease …

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• Guru: What Are Workload Groups And Why Should You Use Them?

  September 13, 2021 Dawn May

  Workload Groups appear to be a hidden gem of IBM i work management. In all my work with clients, I have only encountered one shop actively using workload groups. Introduced in 2010, they provide an additional control on CPU and can also be used to license software products to a fewer number of cores than are active on the partition.

  Workload groups are very simple entities; you add a workload group with the Add Workload Group (ADDWLCGRP) command. You just need to give it a name and how many processor cores, called the processor limit, can be used …

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• Guru: Another Red Flag – Joining On Expressions

  August 30, 2021 Ted Holt

  One would think that a given datum, for example a sales order number, would be defined identically in the various database tables in which it is found within an organization, but one might be wrong. I have on many occasions faced the challenge of joining two or more tables on unmatched data types.

  But it gets worse than that. Sometimes joins involve expressions, which may consist of mathematical operations and/or invocations of functions, both intrinsic and user-written. As with the word DISTINCT in a SELECT, the presence of expression in a join sends up a little red flag that …

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