Hello David, On Tue, October 31, 2017 7:54 pm, David G. Johnston wrote: > On Tue, Oct 31, 2017 at 4:31 PM, Tels <nospam-pg-ab...@bloodgate.com> > wrote: > >> >> >> That looks odd to me, it first uses output_tuples in a formula, then >> overwrites the value with a new value. Should these lines be swapped? >> > > IIUC it is correct: the additional total_cost comes from processing every > output group to check whether it is qualified - since every group is > checked the incoming output_tuples from the prior grouping is used. The > side-effect of the effort is that the number of output_tuples has now been > reduced to only those matching the qual - and so it now must take on a new > value to represent this.
Ah, makes sense. Learned something new today. Maybe it's worth to add a comment, or would everybody else beside me understand it easily by looking at the code? :) Thank you, Tels -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
