On Tue, Nov 17, 2020 at 6:56 PM Etsuro Fujita <etsuro.fuj...@gmail.com> wrote: > * I haven't yet added some planner/resowner changes from Horiguchi-san's > patch.
The patch in [1] allocates, populates, frees a wait event set every time when doing ExecAppendAsyncEventWait(), so it wouldn’t leak wait event sets. Actually, we don’t need the ResourceOwner change? I thought the change to cost_append() proposed in his patch would be a good idea, but I noticed this: + /* + * It's not obvious how to determine the total cost of + * async subnodes. Although it is not always true, we + * assume it is the maximum cost among all async subnodes. + */ + if (async_max_cost < subpath->total_cost) + async_max_cost = subpath->total_cost; As commented, the assumption isn’t always correct (a counter-example would be the case where all async subnodes use the same connection as shown in [2]). Rather than modifying that function as proposed, I feel inclined to leave that function as-is. Best regards, Etsuro Fujita [1] https://www.postgresql.org/message-id/CAPmGK14wcXKqGDpYRieA1ETgyj%2BEp5ntrGVD%3D29iESoQYUx9YQ%40mail.gmail.com [2] https://www.postgresql.org/message-id/CAPmGK17Ap6AGTFrtn3%3D%3DPsVfHUkuiRPFXZqXSQ%3DXWQDtDbNNBQ%40mail.gmail.com
