Re: Parallel Seq Scan

On Mon, Jan 12, 2015 at 3:25 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> On Sat, Jan 10, 2015 at 11:14 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
wrote:
> >> I don't think you should be "switching" queues. The tuples should be
> >> sent to the tuple queue, and errors and notices to the error queue.
> > To achieve what you said (The tuples should be sent to the tuple
> > queue, and errors and notices to the error queue.), we need to
> > switch the queues.
> > The difficulty here is that once we set the queue (using
> > pq_redirect_to_shm_mq()) through which the communication has to
> > happen, it will use the same unless we change again the queue
> > using pq_redirect_to_shm_mq(). For example, assume we have
> > initially set error queue (using pq_redirect_to_shm_mq()) then to
> > send tuples, we need to call pq_redirect_to_shm_mq() to
> > set the tuple queue as the queue that needs to be used for communication
> > and again if error happens then we need to do the same for error
> > queue.
> > Do you have any other idea to achieve the same?
>
> Yeah, you need two separate global variables pointing to shm_mq
> objects, one of which gets used by pqmq.c for errors and the other of
> which gets used by printtup.c for tuples.
>

Okay, I will try to change the way as suggested without doing
switching, but this way we need to do it separately for 'T', 'D', and
'C' messages.

I have moved this patch to next CF as apart from above still I
have to work on execution strategy and optimizer related changes
as discussed in this thread

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com