Re: [EXTERNAL] Re: Analyzing RUNSQLSTMT jobs -- MIDRANGE-L

We have had something very similar happen 3 or 4 times over the past year.
Something that runs every day and takes about 2 minutes to complete (an
inventory report to a customer), will suddenly one day take 8 hours to
run. The job runs, and makes steady progress, but just really slowly.
Looking at the call stack during a slow run, it shows the same spot almost
every time, a procedure in a service program that is using embedded SQL to
extract some data from a file. This procedure is called for every item.
During the last long run, we killed the job, and then immediately
resubmitted it, and it ran in its normal 2 minutes.

The only theory we could muster up is that for some reason when the first
call to that procedure happened, the access path that the SQL normally used
was not available for some reason, so it ended up with a very much less
efficient one. And was stuck with it for the duration of the job. As to
why it wouldn't be available, maybe the system was rebuilding the index?
Maybe Mimix had it locked for whatever it was doing? We have found nothing
to explain this either. We are considering changing the embedded SQL to
RPG and see if the issue ever comes up again.

On Tue, Jul 13, 2021 at 7:58 AM Alan Shore via MIDRANGE-L <
midrange-l@xxxxxxxxxxxxxxxxxx> wrote:

Hi everyone
Here is my latest quirk/conundrum
I ran the reorgs this past weekend and the SQL query that was causing me
heartache ran EXTRMELY quick on Sunday night, with no problems
However, the run on Monday night was STILL running in batch Tuesday
morning – 11 hours later
Now heres the next kicker
I took a copy of the query that is being run, and changed it to create a
file in a different library and ran it interactively
It finished in under 2 minutes
I have NO idea what to look at or even where to start
Does anyone have ANY ideas or hunches
As always – ALL answers gratefully accepted

Alan Shore
Solutions Architect
IT Supply Chain Execution

[cid:image001.png@01D777C5.3A4B1220]

60 Orville Drive
Bohemia, NY 11716
Phone [O] : (631) 200-5019
Phone [C] : (631) 880-8640
E-mail : ASHORE@xxxxxxxxxxxxxxxxxxxx

‘If you're going through hell, keep going.’
Winston Churchill

From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxxxxxxxx] On Behalf
Of Alan Shore via MIDRANGE-L
Sent: Tuesday, July 6, 2021 11:57 AM
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxxxxxxxx>
Cc: Alan Shore <ashore@xxxxxxxx>
Subject: RE: [EXTERNAL] Re: Analyzing RUNSQLSTMT jobs

Thanks for your reply Mark

Re-use deleted records is NOT set on the files that I am looking at. I
would DEFINITELY need to perform a RE-ORG on 3 files in particular THEN
change them to re-use deleted records

Heres another question - hopefully you know the answer.

On at least 2 of the 3 files, there are some join logicals of BOTH of
these 3 files

I was thinking of running 3 separate jobs at the same time doing a re-org
on these 3 files

However - because of the join logicals - will that cause some conflict
between the 2 re-orgs?

Alan Shore
Solutions Architect
IT Supply Chain Execution

[cid:image001.png@01D7725D.FBFDACB0]

60 Orville Drive
Bohemia, NY 11716
Phone [O] : (631) 200-5019
Phone [C] : (631) 880-8640
E-mail : ASHORE@xxxxxxxxxxxxxxxxxxxx<mailto:ASHORE@xxxxxxxxxxxxxxxxxxxx>

‘If you're going through hell, keep going.’
Winston Churchill

From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxxxxxxxx] On Behalf
Of Mark Waterbury
Sent: Tuesday, July 6, 2021 11:52 AM
To: Alan Shore via MIDRANGE-L <midrange-l@xxxxxxxxxxxxxxxxxx<mailto:
midrange-l@xxxxxxxxxxxxxxxxxx>>
Subject: Re: [EXTERNAL] Re: Analyzing RUNSQLSTMT jobs

Alan,

A "mass purge" of database records could impact your applications
performance if those physical files are not using REUSEDLT(*YES), so that a
RGZPFM is needed to reorganize the PF member(s) to reclaim the space used
by the deleted records.

After such a RGZPFM, any and all Logical File access paths over those PF
members need to be updated; if the Logical Files (or physical files with
keys) were not set to MAINT(*IMMED), this access path rebuild will occur on
the next OPEN of that file. This could significantly slow down your
applications, the first time each file is used after such a "re-org."

HTH,

Mark S. Waterbury

On Tuesday, July 6, 2021, 11:30:44 AM EDT, Alan Shore via MIDRANGE-L <

midrange-l@xxxxxxxxxxxxxxxxxx<mailto:midrange-l@xxxxxxxxxxxxxxxxxx<mailto:
midrange-l@xxxxxxxxxxxxxxxxxx%3cmailto:midrange-l@xxxxxxxxxxxxxxxxxx>>>
wrote:

Thanks for your reply Vern
I am wading my way through the document that Jack sent, and it's a LOT of
information to soak in
My problem is that a job that's presently running is still running from
last night
Its been running for about 5 weeks or so - taking different times to
complete - but NOTHING like it is today
However - in my analysis I have discovered that I believe a purge was
recently run on a couple of the files
There are quite a number of deleted rows in these files
My question is - would the deleted rows impact SQL queries?
Forgive my ignorance as I haven't had a decent nights sleep in quite a few
days and Im not thinking straight

Alan Shore
Solutions Architect
IT Supply Chain Execution

60 Orville Drive
Bohemia, NY 11716
Phone [O] : (631) 200-5019
Phone [C] : (631) 880-8640
E-mail : ASHORE@xxxxxxxxxxxxxxxxxxxx<mailto:ASHORE@xxxxxxxxxxxxxxxxxxxx
<mailto:ASHORE@xxxxxxxxxxxxxxxxxxxx%3cmailto:ASHORE@xxxxxxxxxxxxxxxxxxxx>>

'If you're going through hell, keep going.' --Winston Churchill

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