I have seen some refer to indexes as similar to a keyed logical file,
which certainly makes sense to me....however can you not also do the same
thing with a view? IE: Use Order By in a view statement?
From: Doug Palme <DPalme@xxxxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Date: 09/23/2008 09:58 AM
Subject: Re: AW: DDL Discussion continued
----------------------------------------------------------------------
Thanks.....
From: "Birgitta Hauser" <Hauser@xxxxxxxxxxxxxxx>
To: "'Midrange Systems Technical Discussion'"
<midrange-l@xxxxxxxxxxxx>
Date: 09/22/2008 11:57 PM
Subject: AW: DDL Discussion continued
----------------------------------------------------------------------
Hi,
you may also read the following whitepaper which discusses how to
determine
and create the best access paths (either SQL indexes or DDS described
keyed
logical files).
Indexing and statistics strategies for DB2 for i5/OS
http://www-03.ibm.com/servers/enable/site/education/abstracts/indxng_abs.htm
l
Mit freundlichen Gru:ssen / Best regards
Birgitta Hauser
"Shoot for the moon, even if you miss, you'll land among the stars."
(Les
Brown)
"If you think education is expensive, try ignorance." (Derek Bok)
"What is worse than training your staff and loosing them? Not training
them
and keeping them!"
-----Urspru:ngliche Nachricht-----
Von: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] Im Auftrag von
vhamberg@xxxxxxxxxxx
Gesendet: Tuesday, 23. September 2008 03:59
An: Midrange Systems Technical Discussion
Betreff: Re: DDL Discussion continued
Somehow got a quick hit of my palm on the touchpad on the last message -
but
my point was made already.
You should read the manual that talks about optimization and access
plans
and all - it'll tell you why you need indexes for certain kinds of
access
-
the better ones will not even be possible without an index under it. SQL
may
create its own index at time, if it thinks that will go faster than some
other method.
The link to the manual called Database Performance and Query
Optimization,
at V5R4, is
http://publib.boulder.ibm.com/infocenter/iseries/v5r4/topic/rzajq/rzajq.pdf
There'd be a similar manual at the other release levels.
HTH
Vern
-------------- Original message --------------
From: Doug Palme <DPalme@xxxxxxxxxxx>
> We had our meeting this past week on DDL and I would like to get some
> feedback from all of you....I know that some of the uses for a view is
far
> different than an index but if one is depending on the SQL engine to
> determine the most efficient access path for the data, why even create
> indexes? Is there any real advantage to creating them?
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