There are three ways to pass a parameter to a procedure: by reference, by value, and by read-only reference. These methods are not interchangeable, and passing parameters by value can have unfavorable effects on performance. In the following paragraphs, I explain why I make such a statement, I show you how to define parameters for performance, I list the performance figures from my testing, and I provide some recommendations for parameter passing.

Before I go any further, let me get a couple of things out of the way. First, keep in mind that I am talking about you and the

Is there a way to make Open Query File (OPNQRYF) count records that meet certain criteria? I want to write a summary query, using OPNQRYF, that counts all records, and that also counts only the records that have a positive value in one of the numeric fields. Can OPNQRYF do anything like that?

–Dave

When I got Dave’s question, I told him that I thought it could be done, but I’d have to play with it to figure it out. A little while later, Dave had his query and I had another technique to share with you.

It would be

We’ve been doing some performance analysis on our i5/OS V5R3 system and we’ve discovered that the SMIOSTCPGT process is producing an incredible number of synchronous disk operations, which could be slowing down system performance. What is SMIOSTCPGT and what can we do to stop it from bogging things down?

–Joe

Before I start this tip, I’ll come clean and admit that this question came from my own recent experience and it’s a problem I’m trying to find a solution for. I’m presenting the problem here as documentation for other administrators experiencing the same issue and to gather more information on