The number of piped sorts that have been accepted. Consider the following:
If the number of accepted piped sorts is low relative to the number of piped sorts requested, try adjusting either the sort heap or the sort heap threshold.
If you have piped sorts that are being rejected, try decreasing the sort heap or increasing the sort heap threshold.
Note: Either of these choices could incur a cost. For example, increasing the sort heap threshold could retain too much memory for sorting, thus adversely affecting system performance. On the other hand decreasing the sort heap could cause excessive paging and possibly an extra merge phase that could cause the sort to perform poorly.