Re: Question about UDB on iSeries -- MIDRANGE-L

Dave

I can speak to a couple things.

1. The name DB2 was applied to the database on the 38/400 fairly late in the game. I think this was largely a marketing ploy. From the start, however, there was relational capability of some sort in it. Granted, referential integrity, etc. were added late in the game. But I, at least, have been aware that the 38/400 implementation is not the same as the others, under the covers, for sure. SQL, albeit an IBM "invention", was not a part of things early on, but IBM can claim great compliance with current standards. You probably know the www.iseries.ibm.com/db2 site, which includes a cross-platform comparison of the DB2 versions.

2. Of late, IBM recognized the performance problems inherent in the SQL implementation design of things on the iSeries where certain kinds of SQL queries were concerned. The decision was made years ago to focus on embedded SQL, and the rest of the industry went another way - perhaps the "right" way. But development of the new query engine (called SQE now) was begun at least 3-4 years ago, and one performance goal was the performance of the AIX version of DB2 for complex queries like those in the TPC-H benchmark. (I was in the performance lab in 2001, working on this thing.) There are clear differences in the way access plans are developed by the optimizers in AIX and in iSeries. But there is more cross-pollination going on among the various DB2 groups, including Rochester.

3. Certainly you have more knobs to turn in the other flavors of DB2 - the premise of the iSeries was to let the machine handle a lot of this. You can probably, very likely, tune the non-iSeries versions for performance more than you can the iSeries. But there is the tradeoff of personnel to support the others vs. the simplicity with still pretty good performance of the iSeries.

Anyway, enough for now - just to say that IBM Roch is aware of some of the deficiencies, it seems, and is trying to make it better.

I, too, welcome your point of view - as you are able, please provide specifics.

Vern

At 02:12 PM 12/1/2004, you wrote:

John,

You wrote:

>>> Please keep in mind that I know **ZERO** about the iSeries and UDB.
We are considering a conversion from z/OS on zSeries to i5OS on
iSeries..."  <<<

Well, I thought I'd through in my two cents worth since I've been
involved in the following areas of work using the real DB2 RDBMs built
for VM, VSE, and MVS, and the version called DB2/2 on the OS/2 operating
system, and the pseudo-DB2 on the iSeries as well as another highly used
RDBMs, called Oracle:  System Programming, DBA, DA, consultant to
developers of applications using those RBDMS and Director of a
development shop creating multi-terabyte data warehouses using both
DB2/MVS and Oracle.  I even go back to the days of the S/38 and  S/34.


I don't say this to impress but I just didn't see any responses from
folks that have worked with DB2 in the mainframe environment nor other
mid-range industry-accepted RDBMs used on a wide scale, like Oracle.  It
seems like most of the responses are from folks that are prejudiced to
the iSeries and perhaps have limited knowledge of the real DB2.


-snip-