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rpg400-l-request@xxxxxxxxxxxx wrote: > 4. Re: SETOBJACC and file performance (Tony Carolla) > >Hmmm... That sounds promising. I wonder if the system makes a >judgement as to how much of the object to load. Example, I have a >13.7Million record 1.4GB file, and I obviously wouldn't want to tie up >1.4GB of memory, but would the system manage placing only reasonable >portions thereof, based on the pool size? Tony: "...would the system manage placing only reasonable portions thereof" Sounds very close to a piece of an IBM performance manual or redbook that I read that was discussing 'expert cache' back around V3R6/V3R7. Since I'm not totally clear on what your meaning is and I'm not the expert anyway, that might have little to do with your question. But, my understanding of SETOBJACC is something like this (high-level, simplified): You tell the system what pool to load the object into. If the pool isn't big enough, only as many pages as will fit are brought in. The system 'manages' the 'reasonable portion' from then on just as it manages portions of objects anywhere else in memory -- if pages are needed that aren't already in memory no matter what pool they might be in, they're brought in as needed. (I have no idea what pool they might be brought in to if parts are scattered; I suspect job pool gets first crack at it.) Such pages replace pages that haven't been used recently. If other objects are also in this pool, pages from those objects might replace pages of this object. Ideally, this would be used with a private pool. The pool would be assigned to a subsystem and cleared via CLRPOOL to make sure everything in it is flushed out. Once cleared, SETOBJACC brings the requested object into the pool. As long as the pool is private and the object fits in the pool, access will be from memory from then on. If multiple objects are in the pool and they all fit, then they all stay in for the duration, i.e., until SETOBJACC POOL(*PURGE). Objects can be *PGMs or *FILEs. If pools are already set up and used reasonably, I'm not sure that SETOBJACC for a 1.4GB file is likely to buy you much. If large sequences of physical records aren't accessed much, then those pages will just be taking up space with no usage. If all blocks of the file are relatively equal in access and access to the blocks happens numerous times, then _maybe_ there will be improvement; but I'd guess that you better have a lot of spare memory first. Now, if this is a 500-record, 200K file that's used all over the system, programs accessing it over and over again all day long, then carving out dedicated space for it could make a decent difference. At least it wouldn't be in contention for space in a shared pool. I haven't used SETOBJACC since OS/400 V3R2 where I had a major set of issues to overcome for a particular group of applications in a structured day/night environment. It was pretty useful then. But nowadays -- OS/400 V5, large memory spaces, etc. -- I'm way behind in practical knowledge. Hopefully, there will be useful corrections or enhancements to the thread. I wouldn't mind updating what I understand. Tom Liotta -- Tom Liotta The PowerTech Group, Inc. 19426 68th Avenue South Kent, WA 98032 Phone 253-872-7788 x313 Fax 253-872-7904 http://www.powertech.com __________________________________________________________________ Switch to Netscape Internet Service. As low as $9.95 a month -- Sign up today at http://isp.netscape.com/register Netscape. Just the Net You Need. New! Netscape Toolbar for Internet Explorer Search from anywhere on the Web and block those annoying pop-ups. Download now at http://channels.netscape.com/ns/search/install.jsp
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