|
True, but that technique won't get you a listing sorted by customer number and part number out of orderhead ordernbr customernbr 001 001 002 003 003 005 004 001 orderline ordernbr linenbr partnbr 001 001 ABC 001 002 ZYX 002 001 TGH 004 001 ABC 004 002 CDE Rob Berendt -- Group Dekko Services, LLC Dept 01.073 PO Box 2000 Dock 108 6928N 400E Kendallville, IN 46755 http://www.dekko.com michael@xxxxxxxxxxxxxxxxxx Sent by: midrange-l-bounces@xxxxxxxxxxxx 05/03/2005 02:08 PM Please respond to Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx> To Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx> cc Subject RE: Normalization was Left AS/400 and Returned Of course, a lot of RPG programmers don't use join logicals. Instead, they provide their own indexed file navigation by getting a value from one file, using that value to chain to another file, getting value from that file, chaining to another file...and on and on. There's a divide in AS/400-land...those that can/will use SQL or join logicals and want a normalized database, and those who have a series of indexed files and do their own navigation. Basically, if a programmer wants to use more modern techniques, the iSeries can support them. And of course, if a programmer still wants to code in RPG/II, they can. The ability to use 30 year old techniques is a 'feature' on the iSeries. > -------- Original Message -------- > Subject: Re: Normalization was Left AS/400 and Returned > From: rob@xxxxxxxxx > Date: Tue, May 03, 2005 2:55 pm > To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx> > > I agree on the multi-format and join logical files. Or, SQL's views. And > highly recommend them for programming, and, most especially, for common > links the users use in Queries instead of having them join multiple files > together. > > However, he might be right about the performance issue. For example, > which would access faster: > 1 - A key over customer number and part number in a de-normalized > order/line file. > 2 - A join logical that joins the order/header file with the order/line > file so that you can see the customer number from the order header file at > the same time you see the part number of the order line file. And, keep > in mind, that a join logical file does not allow keys from more than one > file, even though I suspect every new release of OS/400 has formed yet > another DCR requesting this feature. This might be possible with an index > on a view in SQL but I don't think that's allowed either. I know you can > get the data this way in a normalized database via SQL but it's going to > do some work under the covers and performance may suffer. > > Rob Berendt > -- > Group Dekko Services, LLC > Dept 01.073 > PO Box 2000 > Dock 108 > 6928N 400E > Kendallville, IN 46755 > http://www.dekko.com > > > > > > "Bill Meecham" <bmeecham@xxxxxxxxxxxxxxxxxxxx> > Sent by: midrange-l-bounces@xxxxxxxxxxxx > 05/03/2005 01:33 PM > Please respond to > Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx> > > > To > "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxx> > cc > > Subject > Re: Left AS/400 and Returned > > > > > > > That's not necessarily true since multi-format and join logical files can > be created and created much easier when the database is normalized. The > reason shops don't normalize is more likely because it's difficult to > master and there is little perceived benefit. Borrowing from another > thread, that's a large part of what case tools help with....normalization > and 'virtualization' of fields. > ----- Original Message ----- > From: michael@xxxxxxxxxxxxxxxxxx > To: Midrange Systems Technical Discussion > Sent: Tuesday, May 03, 2005 2:25 PM > Subject: RE: Left AS/400 and Returned > > > The reason that most vendors and shops don't have normalized databases > is because most vendors and shops don't use the data store on the > iSeries as a database - it's used as a system of indexed files. > Normalization in that scenario can hurt performance, because the > program would need to chain to several files to gather the information > needed to present to the user. There's no doubt that normalization is a > good thing for a database (at least 3NF), but normalization for indexed > files isn't as important or desired. > > -- > This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing > list > To post a message email: MIDRANGE-L@xxxxxxxxxxxx > To subscribe, unsubscribe, or change list options, > visit: http://lists.midrange.com/mailman/listinfo/midrange-l > or email: MIDRANGE-L-request@xxxxxxxxxxxx > Before posting, please take a moment to review the archives > at http://archive.midrange.com/midrange-l. > > > -- > This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list > To post a message email: MIDRANGE-L@xxxxxxxxxxxx > To subscribe, unsubscribe, or change list options, > visit: http://lists.midrange.com/mailman/listinfo/midrange-l > or email: MIDRANGE-L-request@xxxxxxxxxxxx > Before posting, please take a moment to review the archives > at http://archive.midrange.com/midrange-l. -- This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list To post a message email: MIDRANGE-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/midrange-l or email: MIDRANGE-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/midrange-l.
As an Amazon Associate we earn from qualifying purchases.
This mailing list archive is Copyright 1997-2024 by midrange.com and David Gibbs as a compilation work. Use of the archive is restricted to research of a business or technical nature. Any other uses are prohibited. Full details are available on our policy page. If you have questions about this, please contact [javascript protected email address].
Operating expenses for this site are earned using the Amazon Associate program and Google Adsense.