The predefined Hash Join Small Overflows alarm becomes active when a hash join overflows available sort heap space by less than 10%.
This alarm has been predefined with a Low severity level. The underlying metric for this alarm can be adjusted to suit your environment by using the Metric Editor.
If the number of hash join small overflows and hash join overflows are both high, try increasing the SHEAPTHRES database manager configuration parameter. If the number of small overflows number is more than 10% of the number of hash join overflows, try increasing the SORTHEAP database configuration size.