On 2015/11/12 14:09, Kouhei Kaigai wrote:
> I'm now designing the parallel feature of Append...
>
> Here is one challenge. How do we determine whether each sub-plan
> allows execution in the background worker context?
>
> The commit f0661c4e8c44c0ec7acd4ea7c82e85b265447398 added
> 'parallel_aware' flag on Path and Plan structure.
> It tells us whether the plan/path-node can perform by multiple
> background worker processes concurrently, but also tells us
> nothing whether the plan/path-node are safe to run on background
> worker process context.
When I was looking at the recent parallelism related commits, I noticed a
RelOptInfo.consider_parallel flag. That and the function
set_rel_consider_parallel() may be of interest in this regard.
set_append_rel_size() passes the parent's state of this flag down to child
relations but I guess that's not what you're after.
Thanks,
Amit
