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Why DB2?

Dear mainframers,

I'm sorry to bother you in this group but I'm
totally new to this mainframe world but I have a question that I
believe you are the best people to answer.

I'm currently participating in a consulting project
for a financial services client, who as you may imagine has a large
AS400 core, where all their transactional business go thru.

We have been going over an initial assessment of the
applications on this mainframe and I'm now going one abstraction level
down to the programming language and database engine level.
Unfortunnelly I have a IT background but nothing in mainframe, only
Windows and Linux, so I'm quite unaware of all the terminologies.

From what the developers here tell me they have
almost 90% of their data stored outside the DB2 engine, in what they
call files, as was normal legacy practice.

From what I have understood the AS400 system itself
treats these files as tables and you can have logical files being
automatically managed over those.

My problem is: given that they have several Tb of
data, should this be in DB2? Is there a large performance gain in this?
If they don't use SQL, how do they get their records? Sequentially? Can
you make multiple table queries on this primitive platform, or do you
have to merge them in your code? Creating temporary tables each time
you do this?

Any help will be very welcome, thank you very
much, mr_frosty

Dec 15 '06 #1
4 2718
mr_frosty wrote:
Dear mainframers,

I'm sorry to bother you in this group but I'm
totally new to this mainframe world but I have a question that I
believe you are the best people to answer.

I'm currently participating in a consulting project
for a financial services client, who as you may imagine has a large
AS400 core, where all their transactional business go thru.

We have been going over an initial assessment of the
applications on this mainframe and I'm now going one abstraction level
down to the programming language and database engine level.
Unfortunnelly I have a IT background but nothing in mainframe, only
Windows and Linux, so I'm quite unaware of all the terminologies.

From what the developers here tell me they have
almost 90% of their data stored outside the DB2 engine, in what they
call files, as was normal legacy practice.

From what I have understood the AS400 system itself
treats these files as tables and you can have logical files being
automatically managed over those.

My problem is: given that they have several Tb of
data, should this be in DB2? Is there a large performance gain in this?
If they don't use SQL, how do they get their records? Sequentially? Can
you make multiple table queries on this primitive platform, or do you
have to merge them in your code? Creating temporary tables each time
you do this?

Any help will be very welcome, thank you very
much, mr_frosty
The zOS mainframe is on ibm.software.db2.mvs newsgroup
Dec 15 '06 #2
none wrote:
The zOS mainframe is on ibm.software.db2.mvs newsgroup
Actually I think he's talking about iSeries...

--
Serge Rielau
DB2 Solutions Development
IBM Toronto Lab

WAIUG Conference
http://www.iiug.org/waiug/present/Fo...Forum2006.html
Dec 15 '06 #3
mr_frosty wrote:
Dear mainframers,
Historically S/38, AS/400, iSeries, and System i have not been
considered "mainframes", but rather "midrange" systems.
The term mainframe typically refers to the line of systems called
S/360, S/370, etc thru S/390 and System z.

<snip>
From what the developers here tell me they have
almost 90% of their data stored outside the DB2 engine, in what they
call files, as was normal legacy practice.
If the data is stored in externally described physical files, it is
not "outside the DB2 engine".
From what I have understood the AS400 system itself
treats these files as tables and you can have logical files being
automatically managed over those.
Yes - here is a link to some online concepts:
http://publib.boulder.ibm.com/infoce...erminology.htm
A possible point of confusion is that unlike most other platforms,
DB2 is an integrated part of OS/400 (now called i5/OS). There is
no separate DB2 product to install, configure, etc, and DB2
automatically supports physical and logical files that may have
been created through other (non-SQL) interfaces.
My problem is: given that they have several Tb of
data, should this be in DB2?
See above - in all likelihood it already is.
Is there a large performance gain in this?
If they don't use SQL, how do they get their records? Sequentially? Can
you make multiple table queries on this primitive platform, or do you
have to merge them in your code? Creating temporary tables each time
you do this?
I suspect you will need to ask your client such details about their
applications. However there are some facilities like join logical files
that may support some of what you describe.

--
Karl Hanson
Dec 15 '06 #4
I'm currently participating in a consulting project
for a financial services client, who as you may imagine has a large
AS400 core, where all their transactional business go thru.
I hope the client isn't paying too much for you. :-) Normally one
contacts a consultant to get added value and knowledge. Posting in a
newsgroup the client could have done himself IMHO.

Dec 19 '06 #5

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