Extension of the rah command to use tree logic (AIX® and Solaris)

To enhance performance, rah has been extended to use tree_logic on large systems. That is, rah will check how many database partitions the list contains, and if that number exceeds a threshold value, it constructs a subset of the list and sends a recursive invocation of itself to those database partitions.

At those database partitions, the recursively invoked rah follows the same logic until the list is small enough to follow the standard logic (now the "leaf-of-tree" logic) of sending the command to all database partitions on the list. The threshold can be specified by the RAHTREETHRESH environment variable, or defaults to 15.

In the case of a multiple-logical-database partitions-per-physical-database partition system, db2_all will favor sending the recursive invocation to distinct physical database partitions, which will then rsh to other logical database partitions on the same physical database partition, thus also reducing inter-physical-database partition traffic. (This point applies only to db2_all, not rah, because rah always sends only to distinct physical database partitions.)