Em qui, 13 de set de 2018 às 19:53, David G. Johnston < david.g.johns...@gmail.com> escreveu:
> On Thu, Sep 13, 2018 at 3:30 PM, Neto pr <netopr...@gmail.com> wrote: > >> 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. > > Okay, David, but does not it have some SQL statement that returns a time estimate, without having to execute the query? > David J. > >
