DB2 9: Row compression and large RIDs

This article describes the impact of large row IDs (RIDs) on the row
compression feature in DB2 for Linux, UNIX, and Windows. Both large
RIDs and row compression features were introduced in DB2 9. Row
compression can significantly reduce the average row size, but when not
using large RIDs, you are limited by the regular tablespace limits of
255 rows per page. By examining a simple test case of the table ORDERS
from the TPCH database, you’ll see how using large RIDs can circumvent
the limits on the number of rows per page, a relevant factor for
optimizing the benefits of row compression.