RE: Sorting records in Physical and Logical files -- MIDRANGE-L

That's correct until you "Reuse Deleted Records"... In this case, OS400 locates a deleted row in the table and overwrites the old data. This option breaks the arrival sequence rule, so only use RDR on files that you always access by key.

Access path maintenance depends on the file attribute of that name. If MAINT(*IMMED), then new rows get added to the index immediately. IICR, index maintenance

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx]On Behalf Of Booth Martin
Sent: Thursday, August 21, 2008 6:21 PM
To: Midrange Systems Technical Discussion
Subject: Re: Sorting records in Physical and Logical files

As I understand the process, records are always added in arrival
sequence, and the key/address is loaded in arrival sequence also. When
the file is closed the keys themselves are sorted for performance
benefits. The records are left as-is until some action reorganizes them.

Pete Helgren wrote:

Ok. Thanks for that clarification. So, am I correct in assuming that
if the keys were in the order in the DDS I had defined, when an *RPG*
program read them, it would be in the order that the keys were defined
in (as long as K was in the F spec)? Is that also true for logicals?
That is, the ONLY time the keys are determining the "order" of the
records is when they are read through RPG? Then I would expect that if I
opened a physical file in Query OR opened any associated logical in
Query, the records would display in arrival sequence regardless of how
the DDS was defined in either the logical or physical file? If so, that
is new information for me.

I thought DDS had broader implications than just in RPG programs.

Pete

Jim Franz wrote:

SQL is trying to be as efficient as possible.
If you don't ask for ORDER BY, then whatever order it returns is
assumed to be ok. Don't assume by rrn either.
In RPGLE it would be same if the "F" specs had no "K"
to indicate keyed access.
Jim Franz

----- Original Message -----
From: "Pete Helgren" <Pete@xxxxxxxxxx>
To: "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxx>
Sent: Thursday, August 21, 2008 5:26 PM
Subject: Re: Sorting records in Physical and Logical files

In the DDS? I though the point of a logical file was to build an index
that was an alternate to the default sorting sequence of the Physical
file (among other things). Yes, I could issue an ORDER BY using SQL or
OPNQRYF by I though the file had a "natural" sorting order that was set
by the DDS.

So, there is no way to define a physical file using DDS to sort records
in anything other than arrival sequence?

Pete

Alan Shore wrote:

What you are seeing is in fact correct. You have to ORDER BY for the
order
you want

Alan Shore
Programmer/Analyst, Direct Response
E:AShore@xxxxxxxxxxx
P:(631) 244-2000 ext. 5019
C:(631) 880-8640
"If you're going through Hell, keep going" - Winston Churchill

midrange-l-bounces@xxxxxxxxxxxx wrote on 08/21/2008 04:43:26 PM:

I thought I understood this but apparently I don't.

I have a physical and logical file with the following specs:

UNIQUE
R FASA809 TEXT('List Workfile')
-------------------------------------------------------
record layout here:
SLWID 6S 0 COLHDG('Absence ID')
SLW# 6S 0 COLHDG('Seq. Number')
SLWSN 9S 0 COLHDG('Sub SSN')

K SLWID
K SLW#

The logical file looks like:

UNIQUE
R FASA809 PFILE(PASA809)

K SLWID
K SLWSN

The physical file has a randomly generated number in field SLW# and
since the keys are SLWID and then SLW# in that order. I would expect the
file to be ordered that way when I open it up in Query or a simple
select with no ordering in SQL. However, the file is always ordered in
arrival sequence. If I read through this file, I see the records in the
order in which they were written in the file. I *expected* them to be
ordered by the key sequence.

What did I miss or misunderstand?

Thanks

Pete

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