Hi, On 2019-11-27 16:10:20 +0300, Konstantin Knizhnik wrote: > On 27.11.2019 15:12, Rafia Sabih wrote: > > On Wed, 27 Nov 2019 at 12:33, Konstantin Knizhnik > > <k.knizh...@postgrespro.ru <mailto:k.knizh...@postgrespro.ru>> wrote: > > > > Hi hackers, > > > > I wonder how it is possible to prohibit parallel scan for the > > external > > storage accessed through tableam? > > For example if I want to implement specialized tableam for fast > > access > > to temp tables, how can I inform optimizer that > > parallel scan is not possible (because table data is local to the > > backend)? > > > > How about setting parallel_setup_cost to disable_cost in costsize.c for > > your specific scan method. > > How can I do it if i just implementing my AM and not going to change any > postgres code?
I think a set_rel_pathlist hook that prevents parallel paths from being considered would be your best bet for now. But I encourage you to suggest a patch to tableam to support it properly in future releases. Greetings, Andres Freund
