Portal | Manuals | References | Downloads | Info | Programs | JCLs | Mainframe wiki | Quick Ref
IBM Mainframe Computers Forums Index
 
Register
 
IBM Mainframe Computers Forums Index Mainframe: Search IBM Mainframe Forum: FAQ Memberlist Profile Log in to check your private messages Log in
 
Compare VSAM files using DFSORT

 
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> DFSORT/ICETOOL
View previous topic :: :: View next topic  
Author Message
pshongal

New User


Joined: 14 Jun 2012
Posts: 94
Location: India

PostPosted: Thu Nov 23, 2017 10:24 am    Post subject: Compare VSAM files using DFSORT
Reply with quote

Hi,
I have 2 files to be compared each having around 50MM records.

When I do this comparison on flat files, DFSORT takes less time, but when I do this using VSAM files, it takes more time.

I tested in test region with some 400K records (max record length=1450).

Both are variable length files.

Flat file comparison took 0.9 seconds
VSAM file comparison took 9.4 second.

Is there a way I can optimize this?
Back to top
View user's profile Send private message

Nic Clouston

Global Moderator


Joined: 10 May 2007
Posts: 2060
Location: UK

PostPosted: Thu Nov 23, 2017 4:09 pm    Post subject:
Reply with quote

Try using data sets rather than files. And why not try unloading the data sets and comparing the unloads? And those times - are they CPU or wall?
Back to top
View user's profile Send private message
enrico-sorichetti

Senior Member


Joined: 14 Mar 2007
Posts: 10494
Location: italy

PostPosted: Thu Nov 23, 2017 4:19 pm    Post subject:
Reply with quote

it is common knowlege that VSAM processing is heavier than PS processing

Quote:
... why not try unloading the data sets and comparing the unloads?
And those times - are they CPU or wall?


why read twice the input data ( repro + compare )
apart the extra disk space
Back to top
View user's profile Send private message
pshongal

New User


Joined: 14 Jun 2012
Posts: 94
Location: India

PostPosted: Thu Nov 23, 2017 6:44 pm    Post subject:
Reply with quote

As Nic mentioned, I have already tried by unloading VSAM and then compare. It works little better but not a huge impact because its double operation as Enrico mentioned
Back to top
View user's profile Send private message
steve-myers

Active Member


Joined: 30 Nov 2013
Posts: 657
Location: The Universe

PostPosted: Thu Nov 23, 2017 6:53 pm    Post subject:
Reply with quote

In my opinion, Mr. Sorichetti's first sentence should read, "It is common knowledge that sequential VSAM processing requires more CPU time than an equivalent non-VSAM sequential data set."

In addition, you have to unload each data set (s-l-o-w) before the compare (much quicker). You really haven't gained anything!
Back to top
View user's profile Send private message
enrico-sorichetti

Senior Member


Joined: 14 Mar 2007
Posts: 10494
Location: italy

PostPosted: Thu Nov 23, 2017 7:06 pm    Post subject: Reply to: Compare VSAM files using DFSORT
Reply with quote

I stand corrected...
if it is the same for You I would prefer to sit corrected, it is more comfortable icon_wink.gif
Back to top
View user's profile Send private message
View previous topic :: :: View next topic  
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> DFSORT/ICETOOL All times are GMT + 6 Hours
Page 1 of 1

 

Search our Forum:

Similar Topics
Topic Author Forum Replies Posted
This topic is locked: you cannot edit posts or make replies. Data Sets are files. Please stop str... jasorn JCL & VSAM 11 Wed Aug 08, 2018 1:55 am
No new posts USS: Find and replace string within a... vasanthz All Other Mainframe Topics 5 Thu Aug 02, 2018 4:01 am
No new posts Generate and submit JCL and step dyna... vnktrrd DFSORT/ICETOOL 11 Wed Jul 25, 2018 11:31 pm
No new posts How to manage VSAM file update confli... ocjohnh JCL & VSAM 2 Sat Jul 21, 2018 6:04 am
No new posts IKJEFT1B - Cant send 2 files with bot... Time2Live TSO/ISPF 3 Thu Jul 19, 2018 4:56 am

Facebook
Back to Top
 
Job Vacancies | Forum Rules | Bookmarks | Subscriptions | FAQ | Polls | Contact Us