Performance Questions?

[Guest.Visitor]

Hi I have performance question 1. If we have a big PF such as 500,000 records and have LF which was using for both online and batch programs. And sometime many program use it at the same time. The PF is very active one. What (and why) should be use for parameter matainance access path between *IMMED and *REBLD? 2. OPNQRY or LF should be use in a picture of performance? TIA.

[Guest.Visitor]

IMO - If there is a lot of activity(more that every once in a while) on the file you would want *IMMED. You would not want the access path to be rebuilt every time the member is opened, which I think the *rbld option does. Also if the file is used for any type of input verification you also would want the access path to be updated *immed. If you have unique keys you need to use *IMMED.

[Guest.Visitor]

Just 1 LF over the 500,000 record PF? What AS/400 model and OS release/version are you running? That's pretty optimal, I believe. 1) You wouldn't want to use OPNQRYF (or maintain your LF access path other than *IMMED) if you're using that access path for interactive programs. That would definitely impact perceived performance if each user had to wait for the access path to build before they could get to the data. 2) If you keep the number of LF's down, you'll help to keep your I/O performance up there. I've seen shops that have so many LF's, and many are duplicates of ones that already existed. Now that impacts performance, since the system has to maintain all those access paths each time there's a change to the data in the physical file that impacts them. 3) As I understand it, Query Manager will use an existing, handy LF to avoid building its own access path for queries and even OPNQRYF, if it can find it easily enough (another strike against too many useless LF's). This improved performance indirectly, of course, but a bonus of wise LF proliferation. Are you concerned because you're having a specific performance problem, or just a general question?

[Guest.Visitor]

If you have a lot of activity on the file including deleting and adding records it would be a good idea to reorg the file on a regular basis.