Re: Parallel Seq Scan

On Mon, Nov 16, 2015 at 7:39 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Sun, Nov 15, 2015 at 1:12 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
wrote:
> > Thanks for the report.
> >
> > I think main reason of the leak in workers seems to be due the reason
> > that one of the buffer used while sending tuples (in function
> > BuildRemapInfo)
> > from worker to master is not getting freed and it is allocated for each
> > tuple worker sends back to master. I couldn't find use of such a
buffer,
> > so I think we can avoid the allocation of same or atleast we need to
free
> > it. Attached patch remove_unused_buf_allocation_v1.patch should fix the
> > issue.
>
> Oops. Committed.
>

Thanks!

> > Another thing I have noticed is that we need to build the remap info
> > target list contains record type of attrs, so ideally it should not
even go
> > in
> > this path when such attrs are not present. The reason for the same was
> > that the tuple descriptor stored in TQueueDestReceiver was not updated,
> > attached patch fix_initialization_tdesc_v1 fixes this issue.
>
> I don't understand this part.
>

The code in question is as below:

tqueueReceiveSlot(TupleTableSlot *slot, DestReceiver *self)
{
..

if (tqueue->tupledesc != tupledesc ||

tqueue->remapinfo->natts != tupledesc->natts)

{

if (tqueue->remapinfo != NULL)

pfree(tqueue->remapinfo);

tqueue->remapinfo = BuildRemapInfo(tupledesc);

}
..
}

Here the above check always passes as tqueue->tupledesc is not
set due to which it always try to build remap info. Is there any reason
for doing so?

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