radhakrishnan82
Senior Member
Joined: 31 Mar 2005
Posts: 385
Location: chennai, India
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I wish to share this info read from DB2 magazine
People often minimize the size of an "empty" partition of a tablespace by specifying a small value for the PRIQTY associated with the partition (this sets the minimum amount of space that will be allocated for a mainframe DB2 data set). If the partition has been used and purged of data, the associated PRIQTY value can be adjusted downward via the SQL statement ALTER TABLESPACE. A subsequent partition REORG will put the changed PRIQTY into effect. Alternatively, if the purge operation hasn't yet been executed, you can adjust the PRIQTY via ALTER TABLESPACE, accomplishing the purge and changing the PRIQTY value via a LOAD REPLACE utility operation run with a "dummy" input data set.
DB2 for z/OS v.8 delivered some important data partitioning enhancements, including the ability to dynamically add partitions to a tablespace, eliminating the need to predefine partitions for future use. (Partitions that are defined but not yet in use are often made small through a small PRIQTY specification on CREATE TABLESPACE.) Another enhancement makes it possible to cycle through a series of tablespace partitions, so old and purged partitions are reused for new rows corresponding to a newly used partitioning key range. So, with DB2 UDB for z/OS v.8, you can avoid adjusting PRIQTY values for partitions to save space. Simply add a new partition when it's needed (and not before); and, when an old partition is emptied, reuse it instead of leaving it empty.
hope its usefull! |
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