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 Hash join small overflows and Hash join overflow values are both high, try increasing SHEAPTHRES parameters. If the small overflows number is more than 10% of the number of Hash join overflows, try increasing the SORTHEAP size.