On Sun, Dec 24, 2017 at 12:06 PM, Robert Haas <robertmh...@gmail.com> wrote: > On Fri, Dec 22, 2017 at 6:18 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: > >> Also, don't we need to use parallel_divisor for partial paths instead >> of non-partial paths as those will be actually distributed among >> workers? > > Uh, that seems backwards to me. We're trying to estimate the average > number of rows per worker. >
Okay, but is it appropriate to use the parallel_divisor? The parallel_divisor means the contribution of all the workers (+ leader_contribution) whereas for non-partial paths there will be always only the subset of workers which will operate on them. Consider a case with one non-partial subpath and five partial subpaths with six as parallel_divisor, now the current code will try to divide the rows of non-partial subpath with respect to six workers. However, in reality, there will always be one worker which will execute that path. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
