Re: SQL - RRN() not in order

Luis

Someone earlier thought that the optimizer might use an index if there is a high percentage of deleted records - the index would not have any entries for the deleted records and would, therefore, be faster for getting all the active records.

Now that may have been just a guess but it makes sense - did the message that said the index was used give any further information?

Vern

-------------- Original message --------------
From: Luis Rodriguez <luis.rodriguez2@xxxxxxxxx>

Terrence,

I agree (and am very conscious of) with the fact that the only way to guarantee
a result ordered is with the ORDER BY clause.

That said, what I don't really understand is SQL using an index for reporting
the RRN(). One would imagine that kind of things would be better doing a table
scan.

Regards,

Luis Rodriguez

IBM Certified Systems Expert
eServer i5 iSeries Technical Solutions


--- On Sat, 7/26/08, midrange-l-request@xxxxxxxxxxxx
wrote:

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message: 2
date: Sat, 26 Jul 2008 00:13:35 -0400
from: Terrence Enger
subject: Re: SQL - RRN() not in order

Let me remind people--I confess, myself included--that if
you want
results in a specific order, you must specify that order
explicitly.
Even selecting from a keyed logical does not guarantee any
particular
sequence.

This is hard to remember because it so often happens that
the system
will choose a strategy which returns rows in the
"right" order by
accident. Sigh!

Cheers,
Terry.