The problem is that using the explain analyze <query> I have to wait for the query to execute.
I would like to estimate the time without having to wait for the query execution.
Does anyone know how to estimate the time without waiting for the query to be executed?
On the machine in question you have to experiment to obtain data to construct a formula to convert cost to time. Then when using the function remember that lots of things can play into individual executions taking more time (and sometimes less too I suspect) such as locks, caching, physical data locality.
It seems more useful to log actual execution times and look for trends. If you are writing a query odds are it needs to be run regardless of how efficient it may be - or used in a relative comparison to an alternate query.