When you use the facility for returning the total number of hits in the cases listed below, improvement of retrieval performance cannot be expected, and in fact performance may even drop. If performance drops, do not use the facility for returning the total number of hits.

1. If DISTINCT, the ORDER BY clause, or the FOR READ ONLY clause is not specified
2. If the ORDER BY clause is specified and an access path that can cancel the sorting for ORDER BY is selected
   To check whether the sorting for ORDER BY can be canceled, use the access path display utility (pdvwopt). For details about the access path display utility, see the manual HiRDB Version 8 Command Reference.
   
3. If the projection length is short, and the communication volume increase attributed to the 4-byte string length of COUNT(*) OVER() cannot be ignored
4. If the retrieval processing cost is small