The performance problems in this scenario result from the fact that the query work is done independently on each database partition, but the results are consolidated by the coordinating agent, which must wait until all database partitions return a result set.Last Thursday, the last day of this year's Information on Demand (IOD) Conference, while I was doing my presentation on universal table spaces for a second time, I was asked if the the DSNZPARM that allows you to update the partitioning key still existed. If the key was altered and a row was moved from partition 3 to partition 7, all the partitions between 3 and 7 inclusively for the table space and partition index would have to be drained along with any non partitioned indexes on that table. The behavior when updating the column(s) participating in the partitioning key in DB2 10, now that the ZPARM keyword PARTKEYU has been removed, is the equivalent to what you would have received should you had taken the default (YES) in DB2 9. No more parameter choices, no more locking problems.. no longer one of those ZPARMs made famous through a bunch of user group presentations.This limitation is removed beginning with My SQL 5.7.1. Tables employing user-defined partitioning do not preserve the SQL mode in effect at the time that they were created.As discussed in Section 5.1.8, “Server SQL Modes”, the results of many My SQL functions and operators may change according to the server SQL mode.The benefits will normally be worthwhile only when a table would otherwise be very large.
For example, suppose we are constructing a database for a large ice cream company.See NDB and user-defined partitioning, for more information.If, when creating tables with a large number of partitions (but less than the maximum), you encounter an error message such as system variable.Maybe you could even recommend this blog to a friend? Do you have a suggestion for a future blog post, then Click Here And, as usual, please remember: "These comments are my own personal opinions only and do not necessarily reflect the positions or opinions of my employer (IBM) or their affiliates.All comments are based upon my current knowledge and my own personal experiences.