Prior to DB2 12 partition size was limited to 256 GB. The maximum limit on the number of partitions ranged from 4,096 to 64, which is based on page and partition size (DSSIZE value). These limitations existed because data pages were sequentially formatted based on the table space, not based on each data partition.
However, DB2 12 introduces Partition-By-Range Relative-Page-Number (PBR RPN), which provides many structural differences compared to the previous format. For starters, absolute page numbers have been replaced. DB2 12 features relative page numbers (RPN), which represent page numbers without the need for space-consuming embedded partition numbers.
Why RPN table space format in DB2 version 12
The simple answer is the ability to grow the amount of data you store. RPN table spaces enable you to store large amounts of data.
The DSSIZE can grow up to 1 TB for a partition. And the maximum table size increases to 4 PB with up to 256 trillion rows per table.
That is a lot of data that can be stored! Think about it this way: if you were to insert 1000 rows per second it would take more than 8000 years to fill the table to capacity! With RPN table spaces you get the ability to create larger partition sizes. The maximum partition size is now 1 TB (it used to be 256 GB).
So if you are reaching the capacity size of existing table space options, RPN table spaces will allow you to store a LOT more data. Of course, this requires an expanded RID, which increases from 5 bytes to 7 bytes. So that will impact the DDL for the mapping table for your online REORG utilities.
You can find more information on DB2 RPN Table space online here.
With DB2 12 the PBR table space can be in either the new RPN format or in absolute (ABS) format. The format selected is determined by either the PAGENUM value used on the CREATE or ALTER TABLE SPACE statement, or by the PAGESET_PAGENUM system parameter.
The latter is used as the default when PAGENUM isn’t specified on the CREATE or ALTER tablespace statement. To continue using the old format, use PAGENUM ABSOLUTE; otherwise use PAGENUM RELATIVE for RPN.