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yadav2005 · Intermediate Joined: 10 Jan 2005 Posts: 348 Topics: 144

Hai All,

Please help me understanding in some basic simple concepts so that I can understand the process better. There are multiple links to go through them but I would like to know in simple technical terms by experts if somebody can help me.

a) what is Re-org in simple concepts and why do we need and what are the different types and differences between them
b) why and when do we think it is necessary to run reorgs
c) what is mapping table and why it is used in reorgs
d) what is Runstats utility and when and why do we think we have to use
e) what is rebuild index and why and when do we need to do

dbzTHEdinosauer · Posted: Tue Apr 20, 2010 10:44 am Post subject:

The DBA Corner by Craig S. Mullins
Database Fragmentation and Disorganization
_________________
Dick Brenholtz
American living in Varel, Germany

kolusu · Posted: Tue Apr 20, 2010 11:33 am Post subject:

yadav2005,

The key to knowing anything is to READ and READ. If you give up on going thru multiple links , that ends your thirst to learn anything new and don't expect to be spoon fed. The more you learn on your own you tend to remember things for a longer period of time.

Answers :

A and b : http://www.infotel.com/en/newsletter_reorganize.html

C . Mapping Table

D. http://www.hoadb2ug.org/Docs/Smith20612.pdf

E. Short answer :

Indexes are dynamically updated when INSERT, UPDATE, or DELETE operations are performed on a table. As rows are inserted into a table, the indexes expand in number of pages and in number of levels. As rows are updated or deleted, the number of index pages may decrease, but the number of levels remains the same. During deletes, the number of occupied index pages will decrease as pages are emptied, but those pages not completely emptied will be sparsely populated causing an unnecessarily high number of index levels. For performance reasons and storage efficiency, you should rebuild index or drop and recreate indexes after multiple updates and deletes to a table.

Kolusu

yadav2005 · Intermediate Joined: 10 Jan 2005 Posts: 348 Topics: 144

Kolusu and dbz , thanks for your answers , it will really help me a lot.

I will take your suggestions and try to improve myself and read material. It is nice knowing guidance from experts .Thanks once again.

yadav2005 · Intermediate Joined: 10 Jan 2005 Posts: 348 Topics: 144

Kolusu,

I am trying to code Online Reorg JCL , basically we have existing Offline reorg JCL and our rew requirement is to convert them to Online Reorgs and in this regard I am refering to the link given by you and I see many examples:
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dsnugj12/2.23.7?SHELF=&DT=20050323210436&CASE=

My existing code for Offline Reorg:

kolusu · Posted: Wed May 19, 2010 1:22 pm Post subject:

yadav2005,

There is nothing special about online vs offline re-org . The SHRLEVEL parameter determines the type of Re-org. The keyword you are looking for is SHRLEVEL CHANGE

yadav2005 · Intermediate Joined: 10 Jan 2005 Posts: 348 Topics: 144

Thanks Kolusu