Re: Parallel bitmap heap scan

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Mon, Feb 20, 2017 at 6:19 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> The thing that you really have to worry about for this kind of proposal
>> is "what if the query errors out and we never get to ExecEndNode"?
>> It's particularly nasty if you're talking about parallel queries where
>> maybe only one or some of the processes involved detect an error.

> I think that's not actually a problem, because we've already got code
> to make sure that all DSM resources associated with the query get
> blown away in that case. Of course, that code might have bugs, but if
> it does, I think it's better to try to fix those bugs than to insert
> some belt-and-suspenders mechanism for reclaiming every possible chunk
> of memory in retail fashion, just like we blow up es_query_cxt rather
> than trying to pfree allocations individually.

Actually, I think we're saying the same thing: rely on the general DSM
cleanup mechanism, don't insert extra stuff that you expect will get
done by executor shutdown.

regards, tom lane