Re: Scans are offloaded to SeqScan instead of CustomScan when there are multiple relations in the same query

Hi Tom,

I made sure EXPLAIN returns CustomScan for all scans in the query. But
still, ExecCustomScan is only called once while the rest of the functions
are called for each scan separately. Is this expected behavior? How to work
around this?

Thank you!

On Mon, Apr 17, 2023 at 3:45 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Amin <amin(dot)fallahi(at)gmail(dot)com> writes:
> > To simplify: Can CustomScan scan multiple relations in the same query or
> it
> > will always be assigned to one or zero relations?
>
> There's barely any code in the core planner that is specific to custom
> scans. Almost certainly this misbehavior is the fault of your
> custom-path-creation code. Maybe you're labeling the paths with the
> wrong parent relation, or forgetting to submit them to add_path,
> or assigning them costs that are high enough to get them rejected?
>
> regards, tom lane
>