Re: SQL statement to read previous records

AFAIK indexes on the relative record no are only used, when the result must
be sort according the RRN.
Sometime in release 6.1? / 7.1?. the table scan for RRN was changed to an
values list access, i.e. the list containing RRNs is searched first and
with
the result an access to the record performed. Access should be much faster
than with the table scan in the CQE.

Mit freundlichen Grüßen / 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 losing them? Not training them
and keeping them!"

-----Ursprüngliche Nachricht-----
Von: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] Im Auftrag von
Charles Wilt
Gesendet: Wednesday, 18.5 2016 21:31
An: Midrange Systems Technical Discussion
Betreff: Re: SQL statement to read previous records

A quick test on 7.1...

I was able to create the index..

Not sure it was used, in VE I see "Values List" instead of the expected
"Radix index probe"...I see "Values List" as the first step with or without
the index.

This is on a table with 1,220,222 records...and I asked for rrn() = 50,000.

Perhaps I'm doing something wrong.

Charles

On Wed, May 18, 2016 at 2:01 PM, CRPence <crpbottle@xxxxxxxxx> wrote:

On 18-May-2016 11:42 -0500, Charles Wilt wrote:

<<SNIP>> AFAIK, the use of the RRN() function still forces a full
table scan. <<SNIP>>

FWiW: Given an INDEX can be created on RRN(), would seem kinda daft
that such a keyed access path (AccPth) [still] could not be used to
implement a query.

--
Regards, Chuck


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