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Thanks - Most of my curiosity of EVI's is geared towards the goal of
returning the result set in the quickest possible manner.

-----Original Message-----
From: R. Bruce Hoffman, Jr. [mailto:rbruceh@xxxxxxxxxxxxx]
Sent: Friday, October 24, 2003 8:14 AM
To: Midrange Systems Technical Discussion
Subject: Re: Encoded Vector Indexes


----- Original Message -----
From: "Gerald Kern" <gkern@xxxxxxxxxxxxxxxxxxx>
To: "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxx>
Sent: Friday, October 24, 2003 07:57
Subject: RE: Encoded Vector Indexes


> 99% of my SQL is used in embedded RPGLE and ORDER BY is often a
requirement.
> So the ORDER BY could be an issue where it is being used. But I do have a
> few INDEXES that the SQL monitors recomended (that's why they were built
in
> the first place). My thought was that since they are built over one field
> and are used for/by the optimizer only that they would be a better choice
> for performance and storage reasons. But for places where an EVI was built
> to replace an existing index (multi-key fields with order by
implications),
> would SQL sort the result set to accomodate the ORDER BY clause (if it
used
> an EVI)?


EVIs provide no ordering. You would not "replace" a multi-column index used
for ordering with an EVI.

and yes, SQL will usually sort the result to accomodate the ORDER By clause
when EVIs are used. But the purpose of EVIs is to reduce the result set as
rapidly as possible, thereby leaving relatively few records to be sorted to
meet ORDER BY.


===========================================================
R. Bruce Hoffman, Jr.
 -- IBM Certified Specialist - iSeries Administrator
 -- IBM Certified Specialist - RPG IV Developer

"If you pick up a starving dog and make him prosperous,
  he will not bite you. This is the principal difference
  between a dog and a man."

    - Mark Twain





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