Determine if a resultset exists quickly I want to determine if a resultset exists very quickly. At the moment, I'm doing a count - this is taking roughly 55ms, which is unfeasable.The table has ~100k records - I don't care if it has 2, 5, 100k rows that fit a query; I care if it has 0 or 1. Maybe 2 in certain situations.

Is there a way to do this? Would limiting a count using ROWCOUNT (so it only counts about the first 2 rows it finds) speed up the count at all?
If you need just to check existence I'd go with 
SELECT 1 FROM DUAL WHERE EXISTS (SELECT NULL FROM [your query]) ... 

For "top-n" queries there are quite a few alternatives - https://oracle-base.com/articles/misc/top-n-queries . Note, some of them may have side effects ; for instance, where rownum &lt; :value can change optimizer mode to FIRST_ROWS.