At Sun, 30 Dec 2018 12:31:22 +0900, Kohei KaiGai <kai...@heterodb.com> wrote in <CAOP8fzY1Oqf-LGdrZT+TAu+JajwPGn1uYnpWWUPL=2liatt...@mail.gmail.com> > 2018年12月30日(日) 4:12 Tom Lane <t...@sss.pgh.pa.us>: > On the other hands, the later hook must be dedicated to add regular paths, > and also provides a chance for extensions to manipulate pre-built path-list > including Gather-path. > As long as I know, pg_hint_plan uses the set_rel_pathlist_hook to enforce > a particular path-node, including Gather-node, by manipulation of the cost > value. Horiguchi-san, is it right?
Mmm. I haven't expected that it is mentioned here. Actually in the hook, it changes enable_* planner variables, or directory manipuraltes path costs or even can clear and regenerate the path list and gather paths for the parallel case. It will be happy if we had a chance to manpurate partial paths before genrating gahter paths. regards. -- Kyotaro Horiguchi NTT Open Source Software Center