IBM Mainframe Forum Index
 
Log In
 
IBM Mainframe Forum Index Mainframe: Search IBM Mainframe Forum: FAQ Register
 

Query on BLSR


IBM Mainframe Forums -> JCL & VSAM
Post new topic   Reply to topic
View previous topic :: View next topic  
Author Message
Nileshkul

New User


Joined: 09 May 2016
Posts: 24
Location: India

PostPosted: Sat Aug 13, 2016 5:18 am
Reply with quote

Please help with a query on BLSR:
I have a 20 threads for a job running paralally. A VSAM file which has 20 copies used by 20 threads. That means each thread has dedicated copy file of VSAM.
NOW the same VSAM is using BLSR in all threads which I doubt why. Because each thread has it's own copy, there us no sharing of vsam copy file across threads or any other job. Will BLSR degrade performance in this case, Please suggest.
Back to top
View user's profile Send private message
Robert Sample

Global Moderator


Joined: 06 Jun 2008
Posts: 8578
Location: Dubuque, Iowa, USA

PostPosted: Sat Aug 13, 2016 8:05 am
Reply with quote

BLSR improves performances for random access of VSAM data sets (you do NOT have a "VSAM file" -- you have a VSAM data set; the only "files" on z/OS are on tape or in Unix System Services and neither of these can be VSAM). If the data set is being read sequentially, then BLSR won't improve performance (and may make it worse). Notice that the number of threads does NOT factor into whether or not BLSR can improve performance -- only the amount of sequential versus random processing.
Back to top
View user's profile Send private message
Nileshkul

New User


Joined: 09 May 2016
Posts: 24
Location: India

PostPosted: Sun Aug 14, 2016 12:48 am
Reply with quote

Got it now, thanks
Back to top
View user's profile Send private message
View previous topic :: :: View next topic  
Post new topic   Reply to topic View Bookmarks
All times are GMT + 6 Hours
Forum Index -> JCL & VSAM

 


Similar Topics
Topic Forum Replies
No new posts DB2: Need helping below DB2 query DB2 13
No new posts DB2 SQL query to read and update data... DB2 12
No new posts Cobol-db2 : SQL query is running for ... DB2 4
No new posts Reading subsequent rows in a query. DB2 12
No new posts SYSIBM Tables Query DB2 8
Search our Forums:

Back to Top