To help resolve a question posted to a LinkedIn group I manage:
www.linkedin.com/feed/update/urn:li:groupPost:910927-7128598004344786944
... I'd like to find out if there's any way to achieve *true*
Skip-Sequential processing with a Fixed Block Sequential File with a fairly
short record length (i.e
I'd say no, how would you cater for short blocks?
-Oprindelig meddelelse-
Fra: IBM Mainframe Assembler List På vegne af
David S.
Sendt: 11. november 2023 14:59
Til: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Emne: Is True Skip-Sequential Processing Possible with RECFM=FB,DSORG=PS?
To help resolve
David,
it can be done. It doe not matter if you have FB or F- all you have to
know is the geometry of the device it is stored on (or the device it is
does mimic).
If have created a program to do just that (on VSE platform). All it does
is it sets the seeks address for the next record to re
Sure it's possible... BSAM POINT should work fine in general, and BDAM is
even more powerful. However, the previous mention about short blocks is
important; that will foul up block calculations, so you'd probably want to
make it FBS, and make sure there are no short blocks. Presuming your
applica
We do this with DSORG=PS and RECFM=F now.
We load the file with QSAM and keep track of RBNs as we go. At EOF we
rewrite index blocks to predetermined locations in the file with EXCP, then
at READ time we use EXCP to read blocks and convert RBNs to CCHHRs based on
the device geometry as we go.
Mi
On Sat, 11 Nov 2023 10:07:14 -0500 Steve Smith wrote:
:>Sure it's possible... BSAM POINT should work fine in general, and BDAM is
:>even more powerful. However, the previous mention about short blocks is
:>important; that will foul up block calculations, so you'd probably want to
:>make it FBS,
More than a decade ago when I was working as a developer on the
implementation and support of Extended Address Volumes, the plan
of record was to "functionally stabilize" BDAM. At that time there
was zero work planned or being done on BDAM for EAV support. To be
honest, I haven't paid any attent
On Sat, 11 Nov 2023 08:59:07 -0500, David S. wrote:
...
. Sequential processing
*must* begin at specified starting point and there can be *no* reading of
any records prior to that point.
That sounds absurd. So if a block contains 10 records, you want to
be able to read the last 5 with "*n
I agree with Paul regarding the absurdity he mentioned.
Here's another scheme you might want to consider.
Let's call the set of logical records currently at the beginning of
the data set the Restricted Access Set. Presumably, the remaining
records comprise the Unrestricted Access Set.
You coul
On 11/11/23 06:59:07, David S. wrote:
To help resolve a question posted to a LinkedIn group I manage:
www.linkedin.com/feed/update/urn:li:groupPost:910927-7128598004344786944
... I'd like to find out if there's any way to achieve *true*
Skip-Sequential processing with a Fixed Block Sequential Fil
I suspect that a dive into the Unix side is not what he wants to do. But
it's an interesting idea.
My suggestion was primarily for BSAM with POINT. That seems to meet the
OP's needs. The BDAM mention was an aside, and would be overkill.
Although I might say BDAM deserves more respect than it g
> -Original Message-
> From: IBM Mainframe Assembler List
> On Behalf Of David S.
> Sent: Saturday, November 11, 2023 1:59 PM
> To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
> Subject: Is True Skip-Sequential Processing Possible with RECFM=FB,DSORG=PS?
>
> To help resolve a question posted to a Lin
The word record is ambiguous. With BSAM you can point to and read a single
physical record, but it may contain multiple logical records.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
עַם יִשְׂרָאֵל חַי
From: IBM Mainframe Assembler List on b
Are you a betting man?
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
עַם יִשְׂרָאֵל חַי
From: IBM Mainframe Assembler List on behalf
of Paul Gilmartin <0014e0e4a59b-dmarc-requ...@listserv.uga.edu>
Sent: Saturday, November 11, 2023 3:0
It doesn't have to be FBS if you know the location of the block.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
עַם יִשְׂרָאֵל חַי
From: IBM Mainframe Assembler List on behalf
of Binyamin Dissen
Sent: Saturday, November 11, 2023 12:30 PM
T
It is possible to do skip sequential reading of physical records. Itt is not
possible to skip logical records.
There are two cases where it is possible; RECFM=FBS and you know the physical
record number; you know the TTR of the physical record.
It's actually possible to do it in QSAM but this
On Sun, 12 Nov 2023 02:24:50 +, Seymour J Metz wrote:
>It doesn't have to be FBS if you know the location of the block.
>
Doesn't ISPF BROWSE do something of that sort, creating an
index for rapid positioning to a requested record? But it must
(except for FBS?) read once to build the index.
I'm not sure what ISPF does as far as indexing sequence numbers.
For other applications, the devil is in the detail. There are various cases
where the initialization to determine or store TTRs is noise compared to read
time. I had one application where the data changed twice a year. Storing TTRs
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