RE: Record Number

["Bale, Dan" <DBale@xxxxxxxxxxxxxxxx>]

Booth,

Rule #1:  Update files are NEVER blocked on the AS/400 (a pet peeve of mine;
S/36 could block on update, and double-buffer as well!)

AFAIK, access by key, by itself, does not disqualify a file from being
blocked.  This has been a bit of a mystery to me.  If a keyed file is
blocked, how is it blocked?  Is it a contiguous block of physical records
which happens to hold the record being accessed.  Or is the block made up of
(potentially) non-contiguous physical records that follow the keyed access
path?

Blocking is prevented by using OVRDBF SEQONLY(*NO); my original post
mentioned OVRDBF NBRRCDS(1) which I don't think is correct.  Someone else
here can verify that.

Again, I want to reiterate that the RRN retrieved from the INFDS in an
RPG-IV program is _always_ current, regardless of blocking.

- Dan Bale

-----Original Message-----
From: boothm@earth.Goddard.edu [mailto:boothm@earth.Goddard.edu]
Sent: Wednesday, February 16, 2000 7:43 PM
To: RPG400-L@midrange.com
Subject: RE: Record Number


Please go further with this explanation.  I had assumed, apparently 
wrongly, that if a file was accessed by key it retrieved records one at a 
time instead of in blocks.   What has to be done to prevent blocking?
_______________________
Booth Martin
boothm@earth.goddard.edu
http://www.spy.net/~booth
_______________________




"Bale, Dan" <DBale@TFSA.Textron.com>
Sent by: owner-rpg400-l@midrange.com
02/16/2000 04:54 PM
Please respond to RPG400-L

 
        To:     "'RPG400-L@midrange.com'" <RPG400-L@midrange.com>
        cc: 
        Subject:        RE: Record Number


Booth, Jim,

In RPG-III, as in Booth's example, retrieving the file's current RRN 
cannot
be done reliably with just the code you provided.  For input-only files, 
you
risk getting the first RRN in the block of records read.  So, for example,
on your first read you get a block of records that consist of RRN 1 
through
8, the INFDS will report the RRN as being 1 for each of those 8 records. I
believe the way to overcome that is to OVRDBF NBRRCDS(1), although I may 
be
wrong on that.  Since no record blocking occurs with an update file, you
could use this technique without the OVRDBF.

In RPG-IV, I seem to recall that Barbara Morris stated a few months ago 
that
the INFDS reports the current RRN at all times, regardless of record
blocking or the fact that the file is input-only. 

O.K., I just looked it up in the ILE RPG Programmer's Guide, Appendix 
1.1.4
(Behavioral Differences Between OPM RPG/400 and ILE RPG for AS/400) I/O:

    8.  In ILE RPG, the relative record number and key fields in 
        the database-specific feedback section of the INFDS are 
        updated on each input operation when doing blocked reads.

- Dan Bale


-----Original Message-----
From: Martin, Booth [mailto:BoothM@goddard.edu]
Sent: Wednesday, February 16, 2000 3:18 PM
To: 'RPG400-L@midrange.com'
Subject: RE: Record Number


Jim, this worked for me:

     FAPDUE     IF   E             DISK
     FAPDUE1    IF   E           K DISK    INFDS(DB1) 
     F                                     RENAME(RAPDUE:RAPDUE1) 
     FAPDUE2    IF   E           K DISK    INFDS(DB2) 
     F                                     RENAME(RAPDUE:RAPDUE2) 
     FAPDUE3    IF   E           K DISK    INFDS(DB3) 
     F                                     RENAME(RAPDUE:RAPDUE3) 
     D DB1             DS 
     D  DB1RRN               397    400B 0 
     D DB2             DS 
     D  DB2RRN               397    400B 0 
     D DB3             DS 
     D  DB3RRN               397    400B 0

Then, on the subfile I put DB_RRN into a hidden field and could show file 
1,
2, or 3 in the subfile, depending on which file the user requested, and 
then
when a user selected a subfile item I could READS and chain to the 
unindexed
physical file with RRN for updates.


-----Original Message-----
From: Jim Langston [mailto:jlangston@conexfreight.com]
Sent: Wednesday, February 16, 2000 11:46 AM
To: boothm@goddard.edu
Subject: Record Number


I am searching through a file for some strings, and I need to find out
what the record numbers are.  I am opening the file Input, Full 
Procedural,
externally described, and as I understand it, this uses sequential
processing,
that is, record numbers.

Once I find my string, how do I find out what record number I am actually
on?  Until I find out I am going to just increment a counter and hope it's
right, but as we all know, deleted records mess this up.

Thanks.

Regards,

Jim Langston
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