RE: [MI400] change collating sequence

["Raikov, Leonid" <RaikovL1@xxxxxxxxx>]

I'm still investigating. My original idea was that changing the
collating sequence AND REBUILDING THE ACCESS PATH should help. Of
course, just changing the sequence in the object header can't be
expected to work.

Lo

-----Original Message-----
From: Harry Williams [mailto:planesmart@xxxxxxxxxxxx]
Sent: Friday, August 06, 2004 1:04 PM
To: 'MI Programming on the AS400 / iSeries'
Subject: RE: [MI400] change collating sequence


For resorting the file, I have used  OPNQRYF, which is driven by the
QQQUERY
program, or SQL. So not to force a recreation of the Index, I create
logical
files with the Index I need. 

Personally, I don't think you can change the sorting by just changing
the
sort sequence. Though indexing is fun and neat, it still has to be able
to
find the key quickly, last time I was calculating it on the 400, it
appeared
to find its record in 1.4 tries.  From what I understand how the index
works
is to be "sorted" in a way that it can be found physically. Kind of like
the
old Hi Low game.  It looks physically at the middle of the index, if it
needs higher it goes to the middle of the file of the divided piece.
This
high low method will get you to the record in 7 tries. But you
physically
have to have the records in a sequence to do this. I know with B+ triev,
they had an access of about 3.5 tries, where IBM reached 1.4 tries.
Query
and SQL can't do it, you see the indexing or sorting working when a
keyed
path cannot be found. 

If someone has an answer other than this, I will be very excited. 
Harry 









-----Original Message-----
From: mi400-bounces+planesmart=teleteam.net@xxxxxxxxxxxx
[mailto:mi400-bounces+planesmart=teleteam.net@xxxxxxxxxxxx] On Behalf Of
Raikov, Leonid
Sent: Friday, August 06, 2004 5:03 AM
To: 'mi400@xxxxxxxxxxxx'
Subject: [MI400] change collating sequence

Is anybody aware of a way to change the sorting sequence for a logical
without recompiling the DDS? I tried changing the sorting table in the
primary space and forcing the access path recreation, but it does not
seem to be working.

Lo
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