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http://www-03.ibm.com/servers/eserver/iseries/db2/dbmonqrys.htmhas queries you can use to analyze the data, including one for the indexes advised most often. And this link
http://www.redbooks.ibm.com/redpapers/pdfs/redp0502.pdfis an excellent resource for this monitor. A number of the authors are/were from the database performance group in Rochester.
I found those by going to www.iseries.ibm.com/db2 and putting "strdbmon" in the search field. They are also there under various headings under support.
You might also consider contacting Centerfield Technology (used to be called Bradenmark, product name used to be Database Essentials), a former employer of mine. They have a service called database/ASSESSMENT that has you run their command, including the monitor, for a while, then you send the results to them and they give you a report with recommendations, including possible impact of adding indexes. Makes a good one-shot option. www.centerfieldtechnology.com is the site and one of the posters to this list, Elvis Budimlic, works there.
HTH Vern At 05:53 AM 4/10/2006, you wrote:
These are all good suggestions, but one problem is that the client did not buy the source code to the application. The vendor told them they "wouldn't need it" because the vendor would be able to take care of any modifications that were needed. Now that vendor has been sold, and few of the employees were retained. The source code issue will be addressed today as the number one item on my agenda with these folks. They are going to hear that they were penny wise and pound foolish. What is the database monitor Clare mentioned? -- Paul Nelson Arbor Solutions, Inc. 708-670-6978 Cell pnelson@xxxxxxxxxx -----midrange-l-bounces@xxxxxxxxxxxx wrote: ----- To: "'Midrange Systems Technical Discussion'" <midrange-l@xxxxxxxxxxxx> From: "Hauser, Birgitta" <Birgitta.Hauser@xxxxxxxxxxx> Sent by: midrange-l-bounces@xxxxxxxxxxxx Date: 04/10/2006 05:03AM Subject: AW: *Max4GB or *Max1TB Hi, but be aware, if you create additional indexes with the same key fields, additional access paths are created! An index with a 64K page size will not share an access path with a logical file with a smaller page size. Additioal access paths may affect performance as soon as a record gets updated, because all access paths on the based table must be updated. If there are already 250 logical files (with may be 150 different access paths), I'd reconsider to add additional access paths. If you create an index first and after a logical file with the same (or less) key fields in the same sequence the logical file will share the access path with the index and also adopt the larger page size. An SQL index will only share the access path with an other SQL index that has the same key fields in the same sequence. An SQL index with less key fields, but in the same sequence will NOT share an access path with an other index. An SQL index can be used with native I/O like any other keyed logical file. That means it can specified in RPG in the F-Specs like any logical file. In this way, I'd replace keyed logical files without joins or select/omit clauses through SQL indexes. After creating all the new indexes, I'd delete all existing logical files and recreate them, to allow them to share access path and the larger page size with the new indexes. Birgitta "If you think education is expensive, try ignorance" (Derek Bok) -----Urspru:ngliche Nachricht----- Von: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] Im Auftrag von Clare Holtham Gesendet: Montag, 10. April 2006 10:26 An: Midrange Systems Technical Discussion Betreff: Re: *Max4GB or *Max1TB Not BPCS is it??? Seriously, I would certainly change them all to Max1TB, it does improve performance. But Walden is right, it is worth having SQL indexes for the most used ones too. It's well worth just running the database monitor over the app for a while and then creating the indexes recommended. cheers, Clare Clare Holtham Director, Small Blue Ltd - Archiving for BPCS Web: www.smallblue.co.uk IBM Certified iSeries Systems Professional Email: Clare.Holtham@xxxxxxxxxxxxxxx ----- Original Message ----- From: <pnelson@xxxxxxxxxx> To: "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxx> Sent: Sunday, April 09, 2006 12:05 AM Subject: Re: *Max4GB or *Max1TB >I think I'll rip through and change everything in one fell swoop. Next > weekend is Easter, and they won't have anybody working. > -- > > Paul Nelson > Arbor Solutions, Inc. > 708-670-6978 Cell > pnelson@xxxxxxxxxx > > > > > Vernon Hamberg <vhamberg@xxxxxxxxxxx> > Sent by: midrange-l-bounces@xxxxxxxxxxxx > 04/08/2006 05:59 PM > Please respond to > Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx> > > > To > Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx> > cc > > Subject > Re: *Max4GB or *Max1TB > > > > > > > Hi Paul > > I searched the iSeries support site for ACCPTHSIZ and found a couple > things. One has to do with access path sharing-- > > In R410, the default for Access path size (ACCPTHSIZ) changed to > *MAX1TB rather than *MAX4GB on the CRTLF and CRTPF commands and in > the SQL CREATE INDEX statement. Most existing access paths have an > attribute of *MAX4GB. These access paths cannot be shared by access > paths with an attribute of *MAX1TB. For access path sharing to occur, > change existing access paths to ACCPTHSIZ(*MAX1TB) or specify > ACCPTHSIZ(*MAX4GB) on the new access paths. > > The other is from "The System Administrator's Companion to AS/400 > Availability and Recovery" > Redbook http://www.redbooks.ibm.com/redbooks/pdfs/sg242161.pdf > section 16.14, where it says the 4-byte index is supposed to > circumvent seize locks. It also says not to mix the 2 kinds of indexes. > > HTH > Vern > > At 10:16 AM 4/8/2006, you wrote: > >>I've got a client experiencing performance problems with his software >>package. Many of the files have a huge number of logicals built over them >>for various purposes. One has over 250 logicals and joined logicals. All >>of the files are defined as having an acces path size of 4GB. >> >>This system is also being hit with lots of ODBC requests that were >>permitted to be built by the previous IT manager (windoze bigot). >> >>I know how to throttle back the ODBC impact, but should I change the > acces >>path size to 1TB for just the logicals or both the physical and its >>associated logicals to improve the overall performance? >> >>Thanks >>-- >> >>Paul Nelson >>Arbor Solutions, Inc. >>708-670-6978 Cell >>pnelson@xxxxxxxxxx >>-- >>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. > > -- 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.
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