DB2 Version 10.1 for Linux, UNIX, and Windows
DB2 Version 10.1 for Linux, UNIX, and Windows
The ALTER TABLE and CREATE TABLE SQL statements now have a CURRENT MEMBER option in the allowed set of default values.
This change allows you to use the value of the CURRENT MEMBER special register as the default value for the column. This register value is retrieved when the INSERT, UPDATE, or LOAD action is run. You can then partition workloads based on that current member value, and therefore, reduce database contention in a DB2® pureScale® environment.
One method to reduce contention is to add the CURRENT MEMBER column to the table with the ALTER TABLE statement, and then set the table partitioning on the table using that new column. With this approach, newly inserted rows stay local to a member. Consequently, a member has an affinity to specific rows in the table, and therefore the cost of synchronization across members is reduced.
If you experience index contention issues, you can add an implicitly hidden column that has a CURRENT MEMBER default and then use the information in that column to redefine your indexes.
In a DB2 pureScale environment, the static cost of system resource usage is directly proportional to the amount of active sharing that occurs between cluster members. Using the CURRENT MEMBER column to partition a table or an index reduces that level of active sharing between members, and therefore delivers performance gains across the entire environment.